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• Second level
• Third level
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ILOs
• Define microbiology and microorganisms.
• Describe the system of scientific nomenclature
of microorganisms.
• Identify main types of microorganisms
• Differentiate between eukaryotic and
prokaryotic cell.
2020/2021
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What is Microbiology
• Micro= tiny (very small)
• Bio= living
• Logy= the study of
• The study of very small (tiny) living organisms
= The study of microorganisms
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Microorganisms
• They are very small living organisms including bacteria, fungi,
viruses, protozoa and helminths.
• Most of them cannot be seen by naked eye
• They need microscopes to be seen
• Bacteria
• Fungi
Ordinary light microscope
• Viruses
Electronic microscope
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Role of microorganisms in health and disease
• A minority of microorganisms are pathogenic
(capable to produce disease)
• Many of them are colonizing human body as
normal microbiota
• The majority of them play a vital role in
supporting and maintaining nature and life
(saprophytic).
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Nomenclature of Microorganisms
• In bacteria & fungi:
Genus
Starts with
capital letter
2 words
Staphylococcus aureus
Starts with
small letter
Candida albicans
In viruses: single (poliovirus) or two names (not genus and species
(herpes simplex) usually describe clinical condition.
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Types of Microorganisms
Microorganisms
Cellular
Prokaryotic
2020/2021
Non cellular
Eukaryotic
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Viruses
7
Prokaryotic Cell = primitive cell (Bacterial cell)
• Smaller (0.1-5 µm)
• NO true nucleus (single DNA molecule, located inside cytoplasm, NO
histones)
• NO membrane bound intracytoplasmic organelles:
• No mitochondria (respiratory enzymes ae located in cell membrane)
• No Endoplasmic reticulum
• Smaller ribosomes (70 S; 2 subunits: 50 S & 30 S)
• Cell wall is present (except Mycoplasma species): peptidoglycan
in bacteria, chitin in fungi
• No sterol in cell membrane ( lipoprotein only) (except Mycoplasma species)
• Division: Simple binary fission
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Eukaryotic Cell = True cell (Fungal or Human cell)
• Size: Larger (10-100 µm)
• True nucleus (nuclear membrane): present
• Chromosomes: multiple, DNA is associated with histones
• Membrane bound organelles (Mitochondria & End. Reticulum):
present
• Site of respiratory enzymes: mitochondria
• Ribosomes: larger (80 S; 60 S & 40 S)
• NO Peptidoglycan Cell Wall
• Human cell: no cell wall
• Fungal cell: chitin cell wall
• Sterol in cytoplasmic membrane (lipoprotein+ sterol)
• Mitotic division
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1. Nucleoid, Circular simple
DNA
1. True nucleus, Linear complex
DNA
DNA
2. No sterol in cell membrane
Cell
membrane
2. Sterol in cell membrane
3. No membrane bound
intracytoplasmic structures
Cytoplasm
3. Membrane bound
intracytoplasmic structures
4. Smaller ribosomes
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Ribosomes
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4. Larger ribosomes
10
Cell wall is a characteristic for prokaryotes
Extra cellular structures
Cell Wall
Peptidoglycan containing cell wall in bacteria
9/22/2019
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Compare
between prokaryotic & eukaryotic
cells giving an example for each.
Give reasons
Bacterial cell is prokaryotic in nature
(not a true cell)
What is the most important feature
making scientists identifies a newly
discovered microorganism as a bacterium?
2020/2021
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12
Most welcome for questions
2020/2021
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13
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• Second level
• Third level
• Fourth level
• Fifth level
ILOs
1. Demonstrate different components of bacterial cell.
2. Compare and contrast cell wall of Gram-positive & Gram-negative
Bacteria.
3. Differentiate protoplast, spheroplast, L form, and mycoplasma.
4. Describe the structure and functions of bacterial plasma membrane.
5. Differentiate the functions and structure of the nucleoid, ribosomes
and inclusions.
6. Describe the structure and function of the capsule.
7. Compare structure and functions of flagella and pili.
8. Describe the functions of spores, sporulation, and spore germination.
2020/2021
Maha Fathy
2
ILOs
1. Demonstrate different components of bacterial cell.
2. Compare and contrast cell wall of Gram-positive & Gram-negative
Bacteria.
3. Differentiate protoplast, spheroplast, L form, and mycoplasma.
4. Describe the structure and functions of bacterial plasma membrane.
5. Differentiate the functions and structure of the nucleoid, ribosomes
and inclusions.
6. Describe the structure and function of the capsule.
7. Compare structure and functions of flagella and pili.
8. Describe the functions of spores, sporulation, and spore germination.
2020/2021
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Bacterial Cell Structure
Extra cellular structures
Cell Wall
Cytoplasm
+
Intra-cytoplasmic structures
Cell (cytoplasmic) membrane
2020/2021
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Cell wall
It gives the bacteria its shape (rigid structure)
Cocci
Bacilli
Curved Bacilli
Cocco Bacilli
Spirochetes
3/18/2021
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Reaction of bacteria to Gram stain
Gram Positive
Gram positive bacilli
2020/2021
Gram Negative
Gram negative bacilli Gram negative cocci
Gram positive cocci
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Cell Wall structure in gram positive & gram negative
bacteria
2020/2021
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Peptidoglycan Structure (murein or mucopeptide)
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Cell Wall of gram-positive
bacteria
Thick peptidoglycan layer
(repeating sugar subunits
linked by peptide side chains)
Teichoic acid & lipoteichoic
acid (Polymers of glycerol or
ribitol phosphate, major
surface Ag)
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Cell Wall of gramnegative bacteria
Thin peptidoglycan layer
Outer membrane formed of
Lipopolysaccharides (Endotoxins)
Peri-plasmic space
Outer membrane proteins & porins
2020/2021
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Lipopolysaccharides of gram negative
bacteria
2020/2021
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Test your self
What are the unique structures?
Gram Positive
Bacteria
Gram Negative
Bacteria
??????
??????
2020/2021
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Cell Wall Function
1.
2.
3.
4.
5.
6.
7.
Maintains the shape of the bacterial cell (cocci, bacilli … etc).
Supports the weak cytoplasmic membrane.
Provide osmotic protection
Plays a role in cell division.
Responsible for the antigenicity (O Ag in gram –ve bacteria &
Teichoic acid in gram +ve bacteria)
It contains associated proteins: porins for selective
permeability & adhesins for attachment
Responsible for staining properties of the organism.
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Functions of Outer Membrane (of gram-negative bacteria)
• It protects the peptidoglycan from effects of
lysozyme
• It impedes the ingress of many antibiotics
• It is associated with proteins:
• Porins: allow diffusion of some material
• Adhesins: attachment
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• Second level
CELL WALL DEFICIENT BACTERIA
• Third level
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Cell wall deficient bacteria
Naturally occurring
• Mycoplasma
• Sterol containing
Spontaneously
(or artificially) induced)
• L-Forms
plasma
Lab Induced
• Protoplast
• Spheroplast
membrane
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Cell wall deficient Bacteria
Naturally occurring: Mycoplasma
• Smallest type of bacteria
• No defined cell shape
• Resistant to antibiotics which act on cell wall
• Resistant to lysozyme
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Lysozyme
breaks
this bond
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L-Forms
• Can occur Spontaneously (or induced) from some
bacterial genera
( Bacillus, Clostridium, Haemophilus,
Pseudomonas, Staphylococcus, and Vibrio).
By action of antibiotics which can inhibit cell wall synthesis
NB: First discovered in Lister Institute in London
2020/2021
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Medical importance of L-forms
• L-forms can remain viable inside the host
• They can replicate
• They are not killed by antibiotics acting on cell wall
• L-forms can revert to the normal form on removal of the
inhibitor producing relapses of infection.
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Lab induced cell wall deficient bacteria
Protoplast
• Originate from Gram
positive bacteria
Spheroplast
• Originate form Gram
negative bacteria
Cell
membrane
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Outer
membrane
23
Spheroplast
Protoplast
• From gram positive bacteria
• From Gram negative bacteria
• Induced by lysozyme
• Induced by action of lysozyme
on EDTA-treated gram
negative cell (or action of
antibiotics)
• All cell wall material has been
removed
• Spherical structure
surrounded by one
membrane
2020/2021
• Still retaining part of cell wall
(outer membrane)
• Spherical structure surrounded
by two membranes
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How are these cell wall deficient bacteria kept
without rupture???
• By being maintained in an osmotically balanced
medium
• (A solution that has the same concentration of ions
and small molecules as cytoplasm)
2020/2021
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Test your self
•What is the medical
importance of these
altered forms of bacteria
with weakened cell wall?
2020/2021
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• We want to synthesize an antibacterial agent
(antibiotic) to be highly selective (acting
exclusively on bacterial cell and not affecting
human host cells).
• What is the ideal target of this antibiotic???
2020/2021
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Most welcome for questions
2020/2021
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28
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
ILOs
1. Demonstrate different components of bacterial cell.
2. Compare and contrast cell wall of Gram-positive & Gram-negative
Bacteria.
3. Differentiate protoplast, spheroplast, L form, and mycoplasma.
4. Describe the structure and functions of bacterial plasma membrane.
5. Differentiate the functions and structure of the nucleoid, ribosomes
and inclusions.
6. Describe the structure and function of the capsule.
7. Compare structure and functions of flagella and pili.
8. Describe the functions of spores, sporulation, and spore germination.
2020/2021
Maha Fathy
2
STRUCTURES INTERNAL TO CELL WALL
Cytoplasmic
membrane &
mesosomes
2020/2021
Cytoplasm & Intra
cytoplasmic
structures
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3
Cytoplasmic Membrane
Structure
• Composed of protein and
phospholipids
• In contrast to eukaryotic
cells:
• it is rich in protein with
little phospholipids (no
sterol except in
mycoplasma)
2020/2021
Function
• Active transport and selective
permeability
• Involved in protein secretion (extracellular
enzymes and exotoxins) (No endoplasmic
reticulum in prokaryotic cell)
• It contains cytochrome enzyme responsible
for respiration and energy production (No
mitochondria in prokaryotic cell)
• Plays an important role in cell division
Maha Fathy
4
Mesosomes
• They are invaginations of the cytoplasmic
membrane inside the cytoplasm.
• Two types of mesosomes are known as lateral
and septal.
• Septal mesosomes are involved in cell division
where bacterial DNA is attached.
• They increase the surface area of the
cytoplasmic membrane thus increasing the
efficiency of permeability and active transport.
• It is the site for respiratory enzymes.
2020/2021
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Role of septal mesosomes in cell division
2020/2021
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Intra Cytoplasmic
Structures
2020/2021
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Intracellular Structures
•Genetic material
•Ribosomes: protein synthesis
•Storage granules or inclusion granules
2020/2021
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Genetic material
•Bacterial chromosome
•Extra chromosomal DNA: plasmid
2020/2021
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Bacterial Chromosome
• Single molecule of double
stranded DNA (double helix)
• Each strand is a long sequence of
nucleotide units
• The bacterial chromosome carries
the essential genetic materials
(determinants) that control the
bacterial properties and behavior
Sugar
Phosphate
backbone
Hydrogen
bonds
Base
Pairs
• It is a circular molecule free
inside cytoplasm
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The 2 strands are complementary
Replicates by semiconservative method
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Plasmid
• Extra chromosomal double stranded circular DNA.
• Carry certain genetic information, e.g. antibiotic resistance, toxin
production
Genetic information carried by plasmid
are not essential for bacterial life
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Bacterial Plasmid: Define?
• Extrachromosomal DNA
• They are dispensable (not necessary for life of the cell)
• They are capable of self replication (independent of cell replication)
(autonomous)
• Many copies of the same plasmids may present in the same cell.
• Different plasmids may coexist within the same bacterial cell.
• Plasmids can be transferred from one bacterium to another.
• Plasmids can be integrated into the bacterial chromosome
(Recombination).
• Plasmids occur in both Gram-positive and Gram-negative bacteria.
2020/2021
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Ribosomes
• The site of protein synthesis.
• They have sedimentation coefficient
of 70S being composed of 2 subunits:
small 30S and large 50S subunits.
• Aggregates of multiple ribosomes on
a m-RNA are called polysomes
Human cell ribosomes are 80S;
formed of 2 subunits: 60S & 40S
2020/2021
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Inclusion granules
• Round granules observed in cytoplasm of many bacteria.
• These are not permanent or essential structures.
• They are either stored energy or nutrient reserve
concerned with cell metabolism,
• e.g. volutin granules (metachromatic granules of
Corynebacterium diphtheriae).
2020/2021
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STRUCTURES EXTERNAL TO CELL WALL
2020/2021
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Capsule
• Found in some bacteria
• Mostly formed of high molecular weight polysaccharides
(antigenic) or poly peptide
• Can not be seen in Gram stain preparations (special stain)
• An important virulence factor
• Capsular antigens are used for diagnosis & Typing
2020/2021
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The capsule as an important virulence factor
• Antiphagocytic
• Help in attachment of bacteria to
mucous membranes
• Formed only in vivo
2020/2021
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Test your self
Give reason
Capsular polysaccharides
are used for preparation
of vaccines against some
bacteria.
2020/2021
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Slime (Glycocalyx)
• Excreted by some bacteria as loosely attached polysaccharide
material
• Plays an important role in attachment of bacteria to surfaces
and formation of biofilms on biotic or abiotic surfaces
• It plays an important role in pathogenesis of many diseases (as
cystic fibrosis and dental caries)
• Can lead to healthcare associated infection when attached to
devices inserted in human host as IVDs or urinary catheters or
prosthetics like artificial valves or artificial joints
2020/2021
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Flagella & Fimbria (Pili)
2020/2021
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Flagella
• Formed of proteins (Flagellin)
• Found in some gram negative
bacteria
• Make bacteria motile (organelle
of motility)
• An important virulence factor
• They are antigenic and can
stimulate anti-falgellar
antibodies
2020/2021
Fimbria (Pili)
• Formed of glycoproteinprotein (Pilin)
• Found mainly in gram negative
bacteria
• They are important virulence factors
enabling bacteria to adhere to
mammalian cells (colonization)
• Specialized pili are involved in gene
transfer (sex pilus) in a process called
conjugation
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Polar/Monotrichous
Lophotrichous
Amphitrichous
Peritrichous
2020/2021
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Test your self
Give reason
Flagella & pili can play an
important role in
pathogenicity of some bacteria
Mention two functions of
bacterial fimbria (pili)
2020/2021
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BACTERIAL SPORES
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Spores
• Metabolically dormant forms of some species (Bacillus & Clostridia)
• Spore formation occurs outside the body in response to unfavorable
conditions, e.g., depletion of nutrition, accumulation of metabolites
or unsuitable gaseous environment
• They are highly resistant to dryness, heat and chemicals as
disinfectants
• They can live in soil for many years
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Spores (cont.)
• Spores are formed outside the body,
• Can not be stained by ordinary stains like gram
stain (need special spore stain).
• In germination each spore gives rise to a single
vegetative cell which can multiply (it is not a way
of reproduction).
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Sporulation process
• The plasma membrane invaginates
enclosing section of cytoplasm that
contain bacterial chromosome, some
ribosomes, and other cytoplasmic
materials.
• It acquires thick covering protective
keratin-like coat that is responsible
for the remarkable resistance of the
spore to heat, dehydration, radiation,
and chemicals.
2020/2021
Maha Fathy
Septum from
invagination of cell
membrane
Fore spore
Endospore
maturation
Death of mother cell
and release of
endospore
30
2020/2021
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Resistance of bacterial spores
Marked resistance of endospores is attributed to:
• Thick outer keratin like coats (high resistance to heat &
chemicals)
• High content of calcium dipicolinate (protects bacterial
DNA)
• Low water content
• Very low metabolic and enzymatic activity
2020/2021
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32
Test your self
• Which of the following can be used
ideally as an indicator of sterilization
process?
• Vegetative bacteria
• Bacterial spores
2020/2021
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33
Test your self
Give reasons:
• In contrast to fungi, bacterial
spore formation is not considered
a method of reproduction.
• Bacterial spores are formed
outside the body of the host
while capsules are formed inside
host’s body
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Test your self
• Compare between the cell wall structure in
gram-positive and gram-negative bacteria
• Mention the structures present in gram
positive but not in gram negative bacteria
• Mention the structures present in gram
negative but not in gram positive bacteria
• What are the components of the bacterial cell
structure essential for life?
2020/2021
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35
Most welcome for questions
2020/2021
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36
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• Second level
• Third level
• Fourth level
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ILOs
1. Define bacterial growth, and generation time.
2. Describe the process of bacterial replication.
3. Demonstrate the phases of microbial growth and describe their
relation to generation time.
4. Discuss clinical significance of growth curve.
5. Compare and contrast between autotrophic and heterotrophic
bacteria regarding nutritional requirements.
6. Differentiate bacteria according to their gaseous requirements.
7. Describe physical conditions necessary for bacterial growth.
2020/2021
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Bacterial Growth
• The accumulation of biomass and genomic
replication, cell division and an increase in the
number of cells
• It occurs by simple binary fission; each
bacterial cell forms two equal-sized daughter
cells.
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Bacterial Multiplication: Simple Binary
Fission
• The cell became elongated
• Chromosomal replication takes place:
where the double strand DNA separates, each strand acts
as a template for synthesis of new strand by DNA
polymerase enzyme, to produce two identical “daughter”
copies
• Cell wall and cytoplasmic membrane begin to
constrict
• Cross-wall forms separating the 2 daughter cells
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Rate of Bacterial Growth
• Time required for bacteria to double their
number in culture media is called the
generation time
• Some bacteria have short generation time:
(20 minutes for E.coli, 13 minutes for Vibrio
cholerae)
• Some bacteria have long generation time
e.g. Mycobacteria (18 hours)
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Bacterial Growth in vitro
• Most of bacteria can grow on artificial culture media
(fluid or solid media)
• Some bacteria are obligate intracellular (Chlamydia
& Rickettsia): grow on tissue culture
• Treponema pallidum (of syphilis) and Mycobacterium
leprae (of leprosy) can not grow in vitro
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Forms of in vitro bacterial growth
Fluid Media
Solid Media
• Bacterial Growth is
indicated by
turbidity
2020/2021
• A single bacterium supplied with the
appropriate growth requirements will multiply
on the solid medium to from a colony
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Bacterial Growth Dynamics
(Bacterial Growth Curve)
• Second level
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2020/2021
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Bacterial Growth Curve
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Lag phase
• No increase in the number of cells
• They adapt to their new environment.
• They start to synthesize enzymes and
molecules required for bacteria growth
(they may increase in size)
• Its length depends on:
• type of the organism,
• size of the inoculum
• type of growth medium
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Log (exponential) Growth phase
• It is the most active phase of
bacterial growth.
• The number of bacteria
increases steadily by time.
• This phase continues until the
nutrient of the medium is
exhausted or toxic
metabolites accumulate.
Bacteria are highly susceptible to
antibiotics at this phase.
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Stationary phase
• Exhaustion of nutrients and
accumulation of toxic
products
• Decrease in bacterial growth
• Bacterial death is balanced by
formation of new cells
• The number of viable bacteria
remains constant
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Decline phase
• The death rate
increases and exceeds
the multiplication rate.
• This is due to nutrient
exhaustion and
accumulation of toxic
products
2020/2021
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Applications on bacterial growth curve
1
2020/2021
2
3
3 Stages of infectious
disease
1. Incubation Period
2. Clinical disease
(signs &
symptoms)
3. Recovery &
Convalescence
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• In which phase of the
bacterial growth curve do
sporulation of spore forming
bacteria start to occur?
2020/2021
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Requirements
of
Bacterial Growth
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Requirements for Bacterial Growth
Chemical:
• Nutritional requirements: Carbon & Nitrogen
sources and mineral elements
• Gaseous requirements (Oxygen & CO2)
Physical
• Temperature
• Hydrogen ion concentration (pH)
• Osmotic pressure
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Carbon & Nitrogen Sources
• Medically important bacteria require organic
compounds as their carbon sources and called
Heterotrophes
• Autotrophic bacteria synthesize organic metabolites
from CO2, water and mineral salts (saprophytic, free
living bacteria) .
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Heterotrophic bacteria
Exacting (fastidious): require both organic form of carbon
and nitrogen for growth.
• They have complicated nutritional requirements;
• Grow only in special artificial cultures
• Usually they need specific growth factors including yeast
extract, blood, B complex vitamins, amino acids, purines
and pyrimidines
Non-Exacting: Can assimilate organic source of carbon and
inorganic source of nitrogen.
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Oxygen Requirements
• Facultative anaerobe: E.coli
• Obligate anaerobe: Clostridia
• Obligate aerobe: Pseudomonas
• Microaerophilic: Campylobacter
• Aerotolerant (obligate fermenters): lactobacillus
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Obligate aerobe
• They have absolute requirement for
oxygen
• They use O2 as the final electron acceptor
in the process of oxidative
phosphorylation (aerobic respiration)
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• In aerobic respiration the final electron acceptor is O2 to give free
radicals as superoxide anions (O2-) and hydroxyl radicals (OH-)
• These products are toxic to the cell
• They should be eliminated by certain enzymes
2O2- + 2 H
2H2O2
2020/2021
Superoxide dismutase
O2 + H2O2
2 H2O + 2 O2
Catalase
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Obligate anaerobe
• They are killed by oxygen (why?)
• They produce energy through anaerobic
respiration (final electron acceptor is
inorganic substance other than oxygen) or
fermentation (substrate phosphorylation)
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Facultative anaerobe
• They are able to grow in either the
presence or the absence of oxygen.
However, better growth occurs in
the presence of O2
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• Microaerophilic: require limited amounts of
oxygen (5%) for aerobic respiration
• Aerotolerant: Not killed by oxygen but not multiply
in the presence of it (obligate fermenters)
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Carbon Dioxide
• Bacteria need CO2 for growth
• Most of bacteria need CO2 in air concentration
• Few bacteria require additional CO2 (5-10%)
for growth (e.g. pathogenic Neisseria)
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Temperature
• Most pathogenic bacteria grow optimally at 37oC
• Optimum temperature for few bacteria may be higher e.g.
42oC for Campylobacter spp.
• Some bacteria can grow on low temperature (0-4oC) e.g.
Lysteria monocytogenes
( important in food borne illness)
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Bacterial temperature range
•Psychrophilic: range of (5 – 25oC)
•Mesophilic: range of (25 – 45oC)
• Thermophilic: range of (45 – 75oC)
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Hydrogen ion Concentration: (
pH)
• pH refers to the acidity or alkalinity of a solution.
• Most pathogenic bacteria grow best at pH in the
range of 7.2-7.6 (near neutrality)
• Few exceptions:
• Lactobacilli in the vagina prefers acidic pH (e.g. 4)
• Vibrio cholerae prefers alkaline pH (e.g. 8)
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Osmotic pressure
• Most microorganisms grow in optimum osmotic pressure
(the salt concentration of microbial cytoplasm is the same
as the external environment ; 1% NaCl; isotonic).
• Halophilic bacteria: live in marine environments and can
tolerate high salt concentrations.
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What is the main event characterizing the
phase (A) in the corresponding figure of
bacterial growth curve?
• Accumulation of metabolic
intermediates
• Adaptation of the bacteria to the new
environment
• Depletion of nutrients
• Germination of spore forming
bacteria
• Increased susceptibility to antibiotics
2020/2021
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Most welcome for questions
2020/2021
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32
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• Second level
• Third level
• Fourth level
• Fifth level
ILOs
• Discuss relationship between microbes and their hosts.
• Explain importance of normal flora in health and disease.
• Differentiate between colonization and infection.
• List factors affecting host microbe relationship.
• Discuss different bacterial virulence factors.
• Compare between endotoxin and exotoxins.
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Host Microbe Relationships
• Parasitic (pathogenic)
• Pathogenic Bacteria
• Commensal
• Normal Flora
• Mutual
• Vit K producing gut flora
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What is normal flora?
Conjunctiva
Oral cavity
URT
Skin
GIT
Urogenital
tract
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How is it acquired?
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What are their types?
Resident
Transient
Always present on /in
the human body
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Temporarily present under
certain condition
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What are the benefits of normal flora?
Biological Barriers
• Prevent colonization of pathogens through competition
• Cover the binding sites (receptors) used for
attachment
• Consume available nutrients
• Produce components that are toxic to other bacteria
(Bacteriocins)
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• Bacteria can provide some nutrients e.g. Vitamin K,
and also aid in digestion, and absorption of
nutrients.
• Bacterial colonization of the newborn infants acts as
a powerful stimulus for the development of
immune system
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What are the drawbacks of normal Flora?
• Endogenous source for infection
Opportunistic pathogens
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Principles of Infectious Diseases
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Possible outcomes following exposure to
microorganisms
Exposure
Elimination
Colonization
The microbe is
eliminated by host
defenses without affecting
the host.
The microbe has become
established and is
multiplying in / on body
surface of a host.
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Possible outcomes following Colonization
Colonization
Part of normal flora
• Transient
• Resident
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Infection
• Unapparent: subclinical
infection (no symptoms &
signs)
• Clinical Infection (infectious
disease)
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Principles of Infectious Diseases
• Exposure: source of microorganisms
• Colonization: microbe has become established and
is multiplying
• Infection: detrimental effect on the host
(unapparent or latent)
• Infectious Disease: clinical infection; symptoms &
signs
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Important Definitions
• Pathogenicity
The ability of the microorganism to cause disease.
• Virulence
The degree of pathogenicity of an organism
• Virulence factors
Factors help the microbe to cause infection and disease
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Types of Pathogens
• Primary Pathogens: e.g., diphtheria bacilli
• cause disease in healthy individuals
• Opportunistic Pathogens: e.g., uropathogenic E. coli &
coagulase negative staphylococci
• Normal flora when introduced into unusual location
• In immunocompromised host
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Differentiate??
• Clinical infection & Subclinical infection
• Case & Carrier
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Factors Affecting the Host-Microbe Relationship
Microbial factors
• Virulence factors
Host factors
• Immune response:
• Innate
• Acquired
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Bacterial Virulence Factors
A. The ability to adhere to host cells and resist physical removal
B. The ability to resist immediate destruction by host immune
defense
C. Obtaining required iron
D. Invasion and intra cellular survival
E. Type III secretion system dependence virulence in gramnegative bacteria
F. Damage to host cells by inflammatory response or bacterial
products
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A. The ability to adhere to host cells and resist
physical removal
Fimbriae (Pili)
• Uropathogenic E. coli
Non fimbrial adhesins
• E.coli : Diarrhogenic
• Moraxella, Hemophilus,
Bordetella
• Neisseria
• Receptors:
• Urinary tract epithelium
• RBCs
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Other bacterial structures help in adherence
• Teichoic acid in gram positive
bacteria
• Capsule (Pneumococci)
• Glycocalyx (biofilm formation) e.g.,
Coagulase negative Staphylococci
Bacterial biofilm
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B. The ability to resist host immune defense
• Capsule (Pneumococci)
• Immunoglobulin A protease (Pneumococci)
• Cell wall proteins: bind to Fc portion of Ab preventing its action.
• Protein A (Staphylococcus aureus)
• Protein M (Streptococcus pyogenes)
• Intracellular survival (Mycobacterium tuberculosis, Listeria
monocytogenes)
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C. Obtaining required iron: The ability to
compete for iron
• Iron is essential for bacterial growth
• Siderophores: bacterial iron chelators
• Siderophores are synthesized and excreted by the bacterium into
the environment, bind iron, and then re-enter the cell.
Note: Lactoferrin and transferrin – proteins which can
bind iron and limit bacterial growth (humoral barriers
of innate immunity)
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D. Invasion and intra cellular survival
1. Escape intracellular killing by
phagocytic cells and ability to
intracellular growth e.g.,
• M. tuberculosis survives by inhibiting
phagosome-lysosome fusion.
https://www.sciencedirect.com/scien
ce/article/pii/S1931312808001546
• Listeria spp. quickly escapes the
phagosome into the cytoplasm before
phagosome-lysosome fusion.
9/22/2019
https://www.researchgate.net/publication/326528987_Anti
23
microbial_Resistance_in_Listeria_Species/figures?lo=1
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Invasion and intra cellular survival (cont.)
2. Invasins:
They are specific bacterial surface
proteins that allow an organism to
bind to specific receptors and
invade normally non-phagocytic
human cells e.g., invasins of
Shigella spp. and Yersinia spp.
Int. J. Mol. Sci. 2020, 21, 4102; doi:10.3390/ijm
s21114102 , https://www.mdpi.com/14220067/21/11/4102/htm
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Invasion and extra cellular spread (cont.)
3. Spreading enzymes (extracellular spread):
• Collagenase and hyaluronidase (allow the bacteria to
spread through the tissues) e.g., S. Pyogenes
• Lecithinase (breaks down lecithin of cell membrane) e.g.,
C. perfringens (considered as one of bacterial exotoxins)
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E. Type III secretion system
(T3SSs or injectosomes)
• They are syringe like protein
appendages
• Delivers bacterial toxins directly to
the host cell.
• They are found in many species of
gram-negative bacteria e.g., E. coli
and Pseudomonas, Salmonella, Shigella,
Yersinia, Bordetella spp.
https://www.ncbi.nlm.nih.gov/pmc/
articles/PMC2176049/
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F. Damage to host cells
• Immune Mediated Damage
• Bacterial Toxin
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Immune Mediated Damage
Microbial antigens elicit immune response (humoral and cellmediated) resulting in immunopathology which may persist even
after the infection is eliminated.
• Cross-reaction of bacteria-induced antibodies with tissue
antigens e.g., rheumatic fever following S. pyogenes infection
• Delayed hypersensitivity and the granulomatous response e.g.,
cavitation in pulmonary tuberculosis and neurological damage in
leprosy
• Immune complexes damage: e.g., poststreptococcal
glomerulonephritis
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Bacterial Toxins
Effect
Two Main Categories
• Structural toxins (part of cell
wall)
• Secreted toxins (exotoxins)
• Invasiveness and cell damage
• Interfere with the host cell
function
• Trigger IR
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Structural Toxins
• Endotoxin: (Lipid A portion of the outer membrane
Lipopolysaccharides of gram-negative cell wall) which is
the is primary virulence factor in gram negative associated
sepsis & septic shock
• Peptidoglycan and teichoic Acids: released when cells of
gram-positive bacteria die can serve as structural toxins
leading to chemotaxis and immune mediated reaction.
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Bacterial Exotoxins
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Exotoxins
• They are toxic bacterial proteins, which may be
excreted directly into the medium.
• They are produced by a variety of bacteria
including Gram positive and Gram-negative
bacteria
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Structure and Functions of Exotoxin Types
• A-B toxin
• Membrane disrupting toxins
• Super Antigens
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A-B Toxins
• Diphtheria toxin
• Pseudomonas exotoxin A
• Cholera toxin
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Membrane Disrupting Toxins (Cytolytic enzymes)
• Lyses host cells by disrupting the plasma membrane.
• They can affect any host cell
• Their in vitro action is obvious through hemolysis of RBCs
(hemolysins)
Examples
• Lecithinase (phospholipase): C. perfringens.
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Superantigens
• Non-specific (polyclonal) activation of very large
numbers of CD-4 T lymphocytes
• Release of large amount of interleukin-2 and
other cytokines
Toxic Shock (e.g. TSST-1 of S. aureus)
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Superantigen
• Superantigen doesn’t need to be processed by antigen
presenting cells
• It binds to the variable segment of ß chain only (Vß) outside
the TCR
• Many different T cells with different antigen specificities
become activated
• Release of large amount of interleukin-2 and IFN-γ from T-cells
(and other cytokines) Leads to Shock (Toxic Shock)
• Example: TSST-1 (S. aureus)
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Compare
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Exotoxins
Endotoxins
Source
Chemistry
Mechanism of
release
Antigenicity
Effect of
formalin
Action
Specificity
Genetic Origin
Toxicity
Effect of heat
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Summary
• Body of healthy individuals contain normal flora.
• Host-Microbe Relationship are affected by both host factors and microbial factors.
• Steps of bacterial pathogenesis: exposure, colonization, infection, disease production
• Pathogenicity of microorganisms depends on their virulence factors
• Bacteria have many virulence factors
• Endotoxin or LPS is exclusive to, and an integral component of cell wall of Gramnegative bacteria
• Exotoxins are toxic bacterial proteins that are produced by a variety of bacteria
including Gram positive and Gram-negative bacteria.
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Compare and Contrast????
• Toxin & Toxoid
• Septic shock & Toxic shock
• Endotoxin & Exotoxin
• A-B toxin & membrane disrupting toxin with giving
examples
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Define
• Colonization (as a step of bacterial
pathogenesis)
• Bacterial virulence factors
• What are the different factors that help bacteria
in their pathogenesis?
• Describe how bacteria can escape (evade) IR?
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Most
welcome
for
any
question
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
MahaFathy@med.asu.edu.eg
• Fourth level
• Fifth level
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Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Intended Learning Outcomes (ILOs)
1. Identify different components of bacterial cell genetic material.
2. Identify bacterial plasmids and compare it with transposons
regarding structure and properties.
3. Describe structure and importance of bacteriophage.
4. Compare between bacteriolysis and lysogeny.
5. Compare between phenotypic and genotypic bacterial variation.
6. Recognize the differences between mutation and gene transfer.
7. Demonstrate differences between transformation, conjugation, and
transduction.
8. Describe steps and applications of recombinant DNA technology.
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Genetic information in a bacterial cell are carried on:
•Bacterial chromosome.
•Plasmids.
•Transposons.
•Bacteriophages
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Bacterial Chromosome
• Single molecule of double
stranded DNA (double helix)
• Each strand is a long sequence of
nucleotide units
• The bacterial chromosome carries
the essential genetic materials
(determinants) that control the
bacterial properties and behavior
Sugar
Phosphate
backbone
Hydrogen
bonds
Base
Pairs
• It is a circular molecule free
inside cytoplasm
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The 2 strands are complementary
Replicates by semiconservative method
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Test your knowledge
• What are the differences between
bacterial and Eukaryotic
chromosomes?
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Bacterial Plasmids
• Extra-chromosomal circular double stranded DNA
• They are capable of self replication (independent of cell
replication) (autonomous)
• They are dispensable (not mandatory) for life of the cell)
• Two types:
Transmissible
(Conjugative)
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Non Transmissible
(Non conjugative)
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Transmissible (conjugative) plasmids
• Plasmids of Gram –ve bacteria carry genes coding for sex
pili and enzymes required for transfer (tra gene) = F
(Fertility plasmid)
• Can transfer to other bacteria of the same or different
species in a process called conjugation
• They are usually present in a few (1–3) copies per cell
(larger sized).
What are the characteristics of plasmids of Gram negative
bacteria?
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Non-transmissible (non-conjugative) plasmids
• They do not contain the transfer genes
• They are frequently present in many (10–60) copies
per cell (smaller sized).
Plasmids of Gram-positive bacteria are non
transmissible
e.g. plasmids that carry gene responsible for Beta lactamase
production in Staphylococcus aureus.
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Test your knowledge
•Differentiate between
transmissible and Non
transmissible plasmids
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Test your knowledge
• Plasmids of Gram +ve bacteria are
non conjugative (NO tra genes)
How are they mobilized for transfer?
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What are the cell properties determined by plasmids?
1. Antimicrobial drug resistance
2. Virulence:
▪ Exotoxins production.
▪ Pili formation for adhesion.
3. Sex pilus formation for gene transfer (F or
Fertility plasmid)
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Drug Resistance
Genes coding for drug resistance for many bacteria are carried on
plasmid (R-plasmid).
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What is R-plasmid?
• R-plasmid is a transmissible plasmid (extrachromosomal DNA)
carrying genes mediating antimicrobial resistance to different
antibiotics
Examples:
• Chloramphenicol resistance gene
• Penicillin resistance gene
• Tetracycline resistance gene
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Transposons (jumping genes)
• Several
Kbp of DNA capable of
mediating their own movement (jump
or transpose) from one location to
another on the same chromosome or
from plasmid to plasmid or from
chromosome to plasmid
• They are non self replicon i.e. replicate
with the other replicating DNA
molecules e.g. plasmid or chromosome
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Effects of transposition
•They can cause mutations in the gene
into which they insert
•They can alter the expression of nearby
genes.
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Types of Transposons
• Simple transposons (insertion sequence):
They carry genes code only for enzymes responsible for its
transposition (transposase)
• Complex transposons
They carry genes code for enzymes responsible for transposition
plus other genes: e.g.
•
•
Antibiotic resistance genes
Toxin production genes.
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Insertion
Sequence
Complex
Transposon
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Test your knowledge
• How can transposons be
transmitted from one
bacterial cell to another?
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Bacteriophage
• They are viruses that
infect bacterial cells
• They show high
degree of host
specificity
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Interaction between Bacteriophage and Bacterial Host
Two types:
• Bacteriolysis (Lytic cycle): by virulent or lytic phage
• Lysogeny (lysogenic cycle): by temperate phage
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Bacteriolysis (Lytic cycle)
• Infection of a bacterial host with a virulent
phage leads to lysis of the bacterial host cell
and release of new formed phages
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1. Adsorption of the phage to the
bacterial host cell
4. Progeny phage assembly & release
2. Injection of the phage nucleic
acid to the cytoplasm
3. Nucleic acid replication and synthesis
of phage proteins
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Lysogeny (lysogenic cycle)
• Infection of a bacterial host with a temperate phage leads to
integration of phage DNA into the bacterial chromosome.
• The integrated non lytic form which persists in the cell is
called prophage (free in cytoplasm or integrated within
chromosome.
• The integrated prophage replicates within the bacterial
chromosome and transferred to the progeny of the cell
(without cell lysis)
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prophage replicates within the chromosome
and transferred to the progeny of the cell
Lysogenised cells
Lysogenised cell
Integration of the phage DNA into
the bacterial chromosome
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NB
In Lysogeny temperate phage can present either
• Non integrated extra chromosome
Or
• Integrated into bacterial chromosome
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What is the result for the presence of this prophage?
• Lysogenic conversion: The acquisition of new
phenotypic bacterial cell characteristics coded by
prophage e.g.
• Toxigenicity of Corynebacterium diphtheria.
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What is the importance of Bacteriophages?
• Lysogenic conversion (prophage)
• Gene transfer: transfer of genetic information
from one bacterial strain to another by
transduction.
• Bacterial Typing (phage typing): study of
relatedness among bacteria
• Genetic engineering (used as a vector)
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Bacterial Variation
Phenotypic
Genotypic
• A reversible change in the
observable structural and
physiological properties of the cell
without change in bacterial genes.
• A change in the expression of genes
e.g. Spore formation and vegetation
• An irreversible change in
the genome of a bacterial
cell.
• A change in genetic
constitution
• It can occur either by:
• Mutation or
• Usually in response to
environmental condition
• Gene transfer
Define phenotypic or genotypic variation
Compare between phenotypic & genotypic variation
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Compare between genotypic & phenotypic bacterial
variation
Phenotypic
Genotypic
• Reversible
• Irreversible
• Change in gene expression
only
• Change in gene constitution
(mutation or gene transfer)
• Not Heritable
• Heritable
• In response to environmental
conditions
• Spontaneous or induced
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Mutation
• Error usually during replication of DNA leading to change in
nucleotide sequence
• Single base substitution (point mutation)
• Frame- shift mutation (insertion and deletion)
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Mutation
• Spontaneous (natural): during cell multiplication
Or
• Induced by exposure to physical agents (UV or gamma rays) or
mutagenic chemicals (alkylating agents or nitrous acid)
Can lead to antibiotic resistance
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Test your knowledge
•Mention some
applications on
induced mutation
with medical
importance
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Gene Transfer
•Transformation
•Conjugation
•Transduction
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Transformation (Uptake of pure “naked “DNA )
Donor Cell
Recipient
Cell Lysis
Released DNA
DNA taken up by
another cell
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DNA
incorporated
into recipient
cell genome
35
What are the necessary conditions for transformation
to occur?
• Competence: Competent recipient cell
• DNA Homology: There must be DNA homology
between donor &recipient cells
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Does competence occur naturally or artificially?
• Most bacteria are not naturally competent to be transformed by
DNA. Why?
• Bacterial cells contain restriction endonuclease enzymes which
digest any foreign DNA.
• In nature: in some bacteria competence factors are produced at a
specific point in the growth cycle of bacteria that allows free DNA
to cross bacterial the cell membrane
• Competence can be induced artificially in the laboratory by
treating cells with calcium chloride or heat shock which alter cell
membrane permeability
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Conjugation (plasmid mediated) =horizontal transfer
+
+
F+
F+
F
Donor
Recipient
Plasmid Chromosomal
DNA
F
Donor
F
Recipient
Donor
Plasmid Pilus
unwinds formed
one strand remains in the F+ cell while the other
passes through the sex pili to the recipient F- cell
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F
Recipient
A complementary strand is
formed by both cells and
both cells will become (F+)
38
Transduction (Bacteriophage)
• It is the transfer of bacterial DNA from bacterium to another by a
bacteriophage (bacterial virus)= horizontal transfer
• Generalized transduction:
• Phage nucleic acid is not integrated into bacterial
chromosome (lytic or non integrated prophage)
• Specialized transduction:
• Phage nucleic acid is integrated into bacterial chromosome
(integrated prophage)
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Generalized transduction can occur by virulent phage or non
integrated prophage (any part of bacterial DNA can be picked
& transferred)
Bacterial cell
containing both A
& B genes
The bacterial cell
now become
A+ve
Phage carrying
gene A
Phage with gene A
infects another
or B
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bacterial cell (A
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–ve)
Specialized transduction occur by integrated prophage
(A specific part of bacterial DNA is picked & transferred)
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Test your knowledge
Compare between
Generalized transduction &
Specialized transduction
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Recombinant DNA technology &
Genetic Engineering
• Genetic Engineering:
Lab induced modification of the genotypes of
organisms by incorporation of new genes from entirely
different species
• Recombinant DNA
The DNA molecule which contains a new gene
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Recombinant DNA
Vector Extraction
(Bacterial plasmid)
DNA extraction
DNA of interest (specific gene)
Both are treated with the
same restriction enzymes
Joining of the sticky
ends of both the
vector molecule and
the specific DNA
(ligase enzyme)
Recombinant
DNA
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Sticky (cohesive) ends
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Propagation
(Gene Cloning)
The recombinant DNA molecule
is transferred to a bacterial cell
by transformation.
Cell multiply, creating many genetically identical bacteria (clones);
each is able to produce the gene product (usually a protein).
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To summarize: Genetic engineering &
recombinant DNA technology
• Extraction of the wanted DNA sequence (specific
gene)
• Integration of this specific gene into a vector
(plasmid or phage) to produce a recombinant DNA
molecule
• Propagation of the recombinant DNA molecule in a
host organism for gene cloning and production
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Applications on genetic engineering and DNA
recombination
1. Production of a substance (like a hormone
or vaccine)
2. Production of probes for diagnosis of
infectious diseases (hybridization reactions)
3. Gene therapy
4. Chromosome mapping and sequensing
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1. Production of many substances
Like: Hormones (insulin) &
Vaccines (Recombinant Hepatitis B vaccine).
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2. Hybridization reactions used for diagnosis
The use of nucleic acid probe to detect
complementary sequence of microbial genes in
clinical samples.
Molecular diagnosis for DNA detection
without amplification
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3. Gene Therapy
• It involves insertion of a normal gene into human
cells to replace a defective gene to correct a specific
genetic disorder (stem cell technology).
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To summarize
Bacterial variation may be phenotypic or genotypic
Genetic variation can occur in bacteria by mutation and gene transfer
Mutation may be natural or induced
Gene transfer can occur among bacteria by transformation, conjugation
and transduction
• Transformation: is the process by which DNA itself enters a recipient
bacterium.
• Conjugation: DNA (plasmid) is transferred directly from one bacterium
(donor, F+) to another (recipient, F-) through sex pilus
• Transduction: DNA, either plasmid or chromosomal, is transferred from
one bacterium to another by a bacteriophage
•
•
•
•
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Self learning
What do you know about
CRISPR &
CRISPR-Cas
system in bacteria ?
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Most welcome for questions
4/3/2021
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CLASSIFICATION
AND CHARACTERIZATION
• Second level
OF MEDICALLY RELEVANT BACTERIA
(Lecture 1)
• Third level
• Fourth level
• Fifth level
Dr. Makram F. Attalah
Prof. of Medical Microbiology & Immunology
Faculty of Medicine Ain shams University
1
Intended Learning Outcomes
By the end of this lecture students should be able to:
•Identify the approaches for classification of bacteria.
•Identify the basis of phenotypic characterization of medically
important bacteria.
•Identify the basis of molecular biology and genetic
composition of medically important bacteria.
•Mention the important biological properties of medically
relevant bacteria.
2
Classification of
Distinguishing characteristics
Physical properties of the cell wall
Morphology
Growth inside or outside host cell
Reaction to Gram stain
Shape
Oxygen requirements
3
Methods
of
Classification
Identification of Bacteria
A. The old system of classification.
B. The new system of classification.
and
4
The old system of classification
•
•
✓
✓
✓
✓
✓
✓
✓
It was based on phenotypic characteristics.
This system involves some important biological characteristic
as:
Morphology,
Physical properties of cell wall,
Shape,
Reaction to Gram stain,
Oxygen tolerance,
Ability to form spores &
Different enzymatic activities through different biochemical
tests.
5
The new system of classification
• It is based on molecular
biology
and
genetic
composition such as:
1. Nucleotide base composition
[Genomic
guanine
(G)
+
cytosine (C) content]: The
genomic G+C content in the
total DNA is relatively fixed for
any one species.
6
2. DNA base homology: The organisms are arranged
into groups on the basis of the homology of their
DNA base sequences (DNA Fingerprinting).
• Living organisms that look different or have different characteristics
also have different DNA sequences.
• The more varied the organisms, the more varied the DNA sequences.
• DNA fingerprinting is a very quick way to compare the DNA
sequences of any two living organisms.
7
Medically Important Bacteria
8
9
10
Cocci
ClickGram-Positive
to edit Master
title style
Genus
Staphylococci
• Edit Master text styles
Properties:
• Second
level
• Staphylococci
are Gram-positive cocci arranged in
• Fourth level
• Fifth levelirregular clusters (bunches).
grape-like
• All are catalase positive.
• Third level
11
Click
to edit Master
title style
Staphylococci
classification
and important species:
Staphylococci are classified according to coagulase
• Editproduction
Master text styles
into:
• Second level
1.• Third
Coagulase
positive Stapylococci : Staphylococcus aureus
level
• Fourth level
(S. aureus)
• Fifth level
2. Coagulase negative Stapylococci (CoNS): Staphylococcus
epidermidis & Staphylococcus saprophyticus.
positive result
positive result
control drop
12
Staph aureus
Click to edit Master title style
Major
characteristic
• Edit Master text styles
Beta-hemolytic.
• •Second
level
• Third level
• Coagulase-positive.
• Fourth level
• Fifthmannitol
level
• Ferments
on mannitol salt
agar.
• Produce golden yellow endopigment.
• Cell wall contains Protein A that binds
Fc component of IgG and inhibits
phagocytosis.
13
Epidemiology
Click to edit Master title style
colonizes:
• EditItMaster
text styles
• Second
level
• Nasal
mucosa
(20-50 % of population).
• Third level
• Fourth
level
• Skin
specially
heath care workers.
• Fifth level
• Vagina (5%).
• Can be found on contaminated environment e.g.
clothing, bed linens, and fomites.
• Acquisition of infection may be either exogenous or
endogenous.
14
Diseases
Click
to edit Master title style
• Edit Master text styles
•• ThirdLocalized
pyogenic
infections.
level
Fourth level seated infections.
• • Deep
• Fifth level
• Toxin-mediated diseases.
• Second level
15
Localized
pyogenictitle
skinstyle
infections
Click
to edit Master
a furuncle, is a
deep
• Edit
Master text styles
folliculitis,
• Second
infection
of level
• Third level
the hair follicle
• Fourth level
•furuncles
Fifth level
carbuncles
A carbuncle is a cluster of boils, draining pus
onto the skin
impetigo, a common
and highly
contagious skin
infection that causes
sores and blisters.
abscesses
is a collection of pus
that has built up
within the tissue of
the body
surgical site
infections
impetigo
16
Special Program Students Wednesday 24/10/2018
Deep
infections:
Click
to seated
edit Master
title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
osteomyelitis
septic arthritis pyelonephritis
pneumonia cellulitis
mastitis
empyema
Special Program Students Wednesday 24/10/2018
renal abscess
acute endocarditis
17
ClickToxin-mediated
to edit Master title
style
diseases
• EditTSST
Master
-1 text styles
Epidermolytic toxin
Enterotoxin
• Second level
• Third level
Toxic • Shock
Fourth level
• Fifth level
syndrome
Scalded skin
syndrome
Special Program Students Wednesday 24/10/2018
Food
poisoning
18
Staph.
epidermidis
Click
to edit
Master title style
• EditMajor
Master characteristics
text styles
• Second
level
• Coagulase-negative.
• Third level
• Fourth
level
• Non
hemolytic.
• Fifth level
• Novobiocin sensitive.
Special Program Students Wednesday 24/10/2018
19
Epidemiology
Click to edit Master title style
•
Normal
cutaneous
flora.
• Edit Master text styles
• Opportunist,
often by colonizing biomedical devices e.g.
• Second
level
•intravascular
Third level
catheter, shunt, prosthetic devices.
• Fourth level
• Fifth level
Diseases
• Septicemias.
• Endocarditis.
• Wound infections.
Special Program Students Wednesday 24/10/2018
20
saprophyticus
ClickStaph.
to edit
Master title style
• EditMajor
Master characteristics
text styles
• Second
level
• Coagulase-negative.
• Third level
• Fourth
level
• Non
hemolytic.
• Fifth level
• Novobiocin resistant.
Special Program Students Wednesday 24/10/2018
21
Epidemiology
Click to edit Master title style
• Edit Master text styles
•
Urinary
mucosa
colonization.
• Second level
• Third level
Diseases
• Fourth level
• Fifth level
• Urinary
tract infection, most
commonly in sexually active
young women (Honey moon
cystitis).
Special Program Students Wednesday 24/10/2018
22
Genus:
Streptococcus
(streptococci)
Click to edit Master title style
• EditImportant
Master textproperties:
styles
• Second
level
• Streptococci
are Gram-positive
cocci arranged in chains or
•inThird
level
pairs.
• Fourth level
• Fifth level
• All Streptococci are catalase negative.
Special Program Students Wednesday 24/10/2018
23
Streptococci
classification
Click
to edit Master
title style
According
hemolytic activity on sheep blood
• Edit1.Master
textto
styles
• agar:
Second level
Third (ᵝ)
levelhemolytic: cause complete lysis of RBCs
a. •Beta
• Fourth level
e.g. Streptococcus(S)
pyogenes & S. agalactiae.
• Fifth level
b. Alpha (ᵅ) hemolytic: cause partial hemolysis of
RBCs; producing greenish discoloration of blood
agar e.g. viridans streptococci & S.pneumoniae.
c. Non-hemolytic : have no effect on blood agar.
24
2. to
Serological
Classification:
Click
edit Master
title style
• Beta hemolytic Streptococci are further classified
• Edit Master text styles
into
serogroups
(A-O)
according
to
carbohydrate
(C)
• Second level
antigen
• Third level (Lancefield classification) in their cell wall.
• Fourth level
• Fifth level
Special Program Students Wednesday 24/10/2018
25
Click to edit Master title style
• S.
pyogenes
• Edit
Master
text styles (Group
A, beta
• Second
level
hemolytic)
are further
• Third level
serotyped
through
M
• Fourth level
• Fifth level
protein
(Griffith
classification).
• S. pneumoniae are serotyped according to capsular
polysaccharides.
26
Streptococcus
pyogenes
Click to edit Master title style
• EditMajor
MasterCharacteristics
text styles
• •Second
level
Group
A Streptococcal cell wall.
• Third level
• Beta-hemolysis.
• Fourth level
• Fifth level
• Bacitracin-sensitive.
• M protein in cell wall allows
serological typing and it is an
important virulence factor.
27
Epidemiology
Click to edit Master title style
• Found on the skin and in the oropharynx in small numbers.
• Edit Master text styles
Diseases
• Second
level
Third level
• •Pharyngitis/scarlet
fever.
• Fourth level
• Fifth level
• Impetigo/cellulitis/fasciitis/
erysipelas.
• Post-infectious sequelae: acute glomerulonephritis
and rheumatic heart disease.
28
Streptococcus
agalactiae
Click to edit Master title style
• EditMajor
Master Characteristics
text styles
• Second level
• Group
B cell wall carbohydrates.
• Third level
• Fourth level
• Beta-hemolytic.
• Fifth level
• Bacitracin resistant.
29
Epidemiology
Click
to edit Master title style
• Edit• Master
text styles
Commensal
in the vagina of some females, it colonizes
• Second
15% level
to 20%
of pregnant women.
• Third level
• Newborn
• Fourth level infected during birth (increased risk with
• Fifth level
prolonged
labor after rupture of membranes).
Diseases
• Neonatal septicemia, pneumonia, and meningitis.
30
Viridans
streptococci
e.g.
Click to edit Master title style
S. mutans
• EditCharacteristics
Master text styles
• Second
level oral
• Normal
flora.
• Third level
• Alpha-hemolytic.
• Fourth level
• Fifth level
• Not inhibited by optochin.
• Not lysed by bile.
Turbid bacterial
suspension
Turbid bacterial Suspension after
addition of sodium deoxycholate
Reagent (bile salt)
Special Program Students Wednesday 24/10/2018
31
Click to edit Master title style
• EditEpidemiology
Master text styles
• Second
level
• Members
of the resident flora of the oral cavity.
• Third level
Diseases
• Fourth level
• Fifth level
• Major role in dental caries.
• Subacute bacterial Endocarditis.
Special Program Students Wednesday 24/10/2018
32
Streptococcus
pneumoniae
Click
to edit Master
title style
Characteristics
• Edit Master text styles
• Second
level
• Alpha-hemolytic.
• Third level
• Sensitive
• Fourth levelto optochin.
• Fifth level
• Lysed by bile.
Turbid bacterial
suspension
viridan
s
Clear bacterial Suspension after addition
of sodium deoxycholate Reagent (bile
salt)
Special Program Students Wednesday 24/10/2018
33
Epidemiology
Click to edit Master title style
• 5%–50% of the healthy population harbors virulent organisms in
the oropharynx.
• Edit Master
text styles
• Second
levelresults most often when predisposing factors are present
• Disease
•e.g.
Thirdheavy
level smoking, alcohol intoxication, previous viral respiratory
• Fourth level
tract
infections
and splenectomy.
• Fifth level
Diseases
• Lobar pneumonia.
• Otitis media.
• Sinusitis.
• Meningitis in adults.
Special Program Students Wednesday 24/10/2018
34
faecalis
ClickEnterococcus
to edit Master
title style
Enterococcus faecium
• Edit Master text styles
• Second level
• Third level
Characteristics
• Fourth level
• Fifth
• Group
D level
streptococcal cell wall carbohydrates.
• Salt and bile tolerance.
• High pattern of antibiotic resistance.
Special Program Students Wednesday 24/10/2018
35
Click
to edit Master title style
Epidemiology
• Their natural habitat is in the human intestines.
• Edit Master text styles
• Theylevel may
cause
diseases
outside
the
• Second
•gastrointestinal
Third level
tract
particularly
in
hospitalized
or
• Fourth level
immunocompromised
patients.
• Fifth level
Diseases
• Endocarditis.
• Septicemia.
• Urinary tract infections.
Special Program Students Wednesday 24/10/2018
36
Peptostreptococcus
Click
to edit Master title style
• Edit•Anaerobic
Master text stylesstreptococci.
• Second level
•Opportunists.
• Third level
• Fourth level
• Fifth level
Special Program Students Wednesday 24/10/2018
37
Gram-Positive Cocci
Click
to
edit
Master
title
style
Differentiation of Medically Important Gram Positive Cocci
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
R
S
Special Program Students Wednesday 24/10/2018
38
Gram
Positive
Click to edit
Master
title styleBacilli
• EditNon
Masterspore
text styles
• Second level
forming
• Third level
• Fourth level
• Fifth level
Corynebacteria
Listeria
Special Program Students Wednesday
Spore forming
Aerobic
Anaerobic
Bacillus group
Clostridia group
39
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Special Program Students Wednesday 24/10/2018
40
Genus
: Bacillus
Click
to edit
Master title style
Important
members
• Edit Master
text styles
• Second level
• Third level
• B anthracis
• Fourth level
• Major
Characteristics
• Fifth level
• Aerobic spore forming large Gram positive bacilli occurring in
chains
• Have polypeptide capsule
(poly-d- glutamate)
Special Program Students Wednesday 24/10/2018
41
41
ClickEpidemiology
to edit Master title style
•Most members of the genus bacillus are saprophytic
• Editorganisms
Master textinstyles
soil, water and air.
• Second
•Few level
are pathogenic
• Third level
•contact
• Fourthwith
level infected animals or inhalation of spores (zoonotic)
• Fifthbioterrorism
level
•Potential
agent
•Diseases
•Anthrax disease
•-Cutaneous (malignant pustule)
•-Inhalation (wool sorters’ disease)
•-Intestinal (rare). Special Program Students Wednesday 24/10/2018
Special Program Students Wednesday 24/10/2018
42
42
Click
edit Master title style
B. to
Cereus
• EditEpidemiology
Master text styles
• Second level
Saprophytic
found in nature
• Third level
• Fourth level
• Fifth level
•Diseases
• Food poisoning
• Associated with food kept warm, e.g. Chinese fried rice
• Eye infections (rare)
Special Program Students Wednesday 24/10/2018
Special Program Students Wednesday 24/10/2018
43
43
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Special Program Students Wednesday
24/10/2018
44
Click to edit Master title style
• Edit Master text styles
CLASSIFICATION AND
CHARACTERIZATION OF
MEDICALLY RELEVANT BACTERIA (2)
• Second level
• Third level
• Fourth level
• Fifth level
Dr. Wafaa khalil zaki
Prof. of Medical Microbiology & Immunology
Intended Learning Outcomes
By the end of this lecture students should be able to:
Mention the important biological properties of :
• Gram-positive
bacilli : clostridium ,Corynebacterium
,Actinomyces, Nocardia .
• Gram negative cocci N. meningitids & N. gonorrheae
• Gram negative rods (Enterobacteriaceae)
• Gram negative rods (Non fermenting aerobic )pseudomonas .
• Curved Gram negative Bacilli : Vibrio ,Campylobacter,
Helicobacter.
Gram Positive bacilli
Aerobic
non
spore
forming
Gram-positive
bacilli
Click to edit Master title style
Listeria
Corynebacterium diphtheriae
➢ Aerobic,
• EditCharacteristic
Master text
stylesGram positive bacilli, non-
•
➢
Short, Gram positive, , non spore forming
bacilli. Motile , distinguish from diphtheria
by motility .
spore forming, club shaped (with
Second level one swollen end and another
• Third level tapering end) , Chinese letters like
arrangement, non motile
• Fourth level
➢ It is found in G.IT of animals, transmitted by
• Fifth level
Man is the only reservoir (case or
unpasteurized milk, Dairy products (zoonosis)
carrier)
transmission: droplet (main) and
contact
Diseases
Diphtheria
Listeriosis
Click to edit
Master title style
CLOSTRIDIUM
Gram-positive , spore forming large
• Edit Master
styles . All members are
bacilli,text
Anaerobic
motile and non capsulated
• Second level
• Third level
EXCEPT
C. perfringens.
• Fourth level
• Fifth level
The organisms are found in the intestine
of man, animal, and soil.
Pathogenicity of the organisms due to
exotoxins production
tetani
ClickClostridium
to edit Master
title style
(Cl. tetani )
• Edit
Master
stylesanaerobic,
• They
aretext
large,
• Gram-positive,
Second level
• Third level
spore-
forming
bacilli.
• Fourth level
• Fifth
level
• Produces
tetanus
toxin
• Their natural habitat is the soil
and the lower intestinal tract of
man and animals
• Transmitted through puncture
wounds/trauma
• (requires low tissue
Oxygenation)
Cl.toperfringens
Click
edit Master title style
• Nonmotile “stormy
fermentation” in milk
• Edit Master text styles
media
• Second level
•• Double
Third level zone of
• Fourth level
hemolysis
• Fifth level
➢food borne and traumatic
implantation .
➢The main cause of gas
gangrene and can cause
food poisoning
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Cl.
botulinum
Click to edit Master title style
➢Produces botulinum toxin
• Edit Master text styles
food borne
•➢Transmission:
Second level
• Third level
➢Food
poisoning
(botulism)
• Fourth
level
• Fifth level
Clostridium
difficile
Click
to edit Master
title style
• Edit Master text styles
• Second level
• ThirdAntibiotic
level
• associated
Fourth level
• Fifth level
pseudomem
branous
colitis
Click
to edit Master
titleforming
style Gram positive
Filamentous
non spore
• Edit Master text styles
bacilli
• Second level
• Third level
• Fourth level
• Fifth level
Aerobic: Nocardia
Anaerobic: Actinomyces
ACTINOMYCETES
Click to edit Master title style
Actinomyces israelii
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Anaerobic Gram-positive bacilli that tend to form
long branching filaments, Non−acid fast
Nocardia
asteroides
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
• It is strict aerobic Gram-positive bacilli that form branched
filaments.
• It is weak acid fast (5% sulphuric acid).
weak acid fastness, aerobic growth differentiate Nocardia from
Actinomyces.
ACTINOMYCES
NOCARDIA
Click to
edit Master
styleStrict Aerobic; Gram-positive branching bacilli,
- Anaerobic , title
Gram-positive
Characteristic
Branching bacilli, Non−acid
fast
- Most members are normal
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Diseases
flora colonize the mouth,
upper respiratory tract,
gastrointestinal tract and
female genital tract that can
cause disease when the
normal mucosal barrier is
disrupted
actinomycosis;
draining abscesses
Endogenous infection
weakly acid-fast.
-
They are environmental saprophytes that
cause disease in immunocompromised
individuals (opportunistic pathogens).
Nocardiosis
❑ N. asteroides cause bronchopulmonary
nocardiosis.
❑ N. brasiliensis cause Actinomycetoma
Gram Negative Cocci
ClickGenus:
to edit
Master
title
style
Neisseria
• Edit
Master text
styles and species:
Important
properties
• •Second
level are oxidase positive aerobic Gram
Neisseria
• Third level diplococci; occurring as pairs with
negative
• Fourthadjoining
level
flattened
sides.
• Fifth level
• All ferment glucose.
• They colonize mucosal surfaces (both pathogenic
and non pathogenic).
• The pathogenic members of the group includes N.
meningitidis) is capsulated and maltose fermenter
however, N. gonorrheae is not capsulated and non
–maltose fomenter causes gonorrhea.
15
Negative
Rodsstyle
(bacilli)
ClickGram
to edit
Master title
Enterobacteriaceae
• Edit
Master text styles
(Fermenting
Gram
Negative
•Bacilli)
Second level
• Third level
• This• is
a large
family of fermenting Gram-negative rods that
Fourth
level
• Fifth level
includes
many genera as: Escherichia, Klebsiella,
Enterobacter, Proteus, Salmonella, Shigella & Yersinia.
16
Natural
Habitat:
Click to edit Master title style
• The majority are present as the normal flora in the
colon text
ofstyles
both man and animals (e.g. E. coli
• Edit Master
• Second
level
,Klebsiella
).
• Third level
• Some
are
• Fourth
level saprophytes in water, soil and plants (e.g.
• Fifth level
Proteus
a cause of UTI .
• Few of them are primarily intestinal pathogens (e.g.
Salmonella & Shigella).
17
Click
to edit Characteristics
Master title style
General
of Enterobacteriaceae
Family:
• Edit Master text styles
• Theylevelare
• Second
Gram-negative bacilli. non spore forming,
•non-capsulated
Third level
(with
few
exceptions).
• Fourth level
Fifth level
• They• are
motile with peritrichate flagella (with few
exceptions).
• They can grow on ordinary media as well as on
selective and differential media e.g. MacConkey’s
agar .
18
Click to
edit
Master
title
style
All members share 4 common characteristics:
1. Facultative
• Edit Master
text styles
anaerobe.
• Second level
2.
Oxidase
negative.
• Third level
• Fourth level
3. Reduce
nitrate to nitrite.
• Fifth level
4. Ferment glucose (either ┴ or ┼).
19
Antigenic
structure
O,H &K
Click
to edit Master
title. style
➢ O antigen (somatic antigen ) it is the outer polysaccharide
• Edit Master text styles
portion of the lipopolysaccharide.
• Second level
• Third level
Fourth level
➢ H• antigen
is the flagellar antigen .
• Fifth level
➢ K antigen is the capsular antigen .
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Click
to edit Master
Escherichia
coli title style
• Edit• Master
Motiletext
andstyles
Lactose
• Second
level
fermenter
• Third level
• Indole
positive
• Fourth
level
• Fifth level
• Some strains are
capsulated
• Major component of normal
colon flora, may colonize
vagina or urethra
• Can be acquired
endogenous or exogenous
through contaminated hands
of HCWs
• Diarrheagenic strains may be
transmitted through
contaminated water or food
Special Program Students Sunday 28/10/2018
Click to edit Master title style
Causetext
diseases
• Edit• Master
styles inside & outside GIT
• Mostlevel
common cause of urinary tract infection
• Second
Third level meningitis
• •Neonatal
• Fourth level
• Common
of different health care associated infections
• Fifthcause
level
(UTI, SSI, Septicemia, VAP*)
• Some strains can cause diarrhea (Diarrheagenic E. coli)
Klebsiella
spp. title style
Click
to edit Master
• Edit•Master
text styles
Capsulated,
non-motile
• Second level
• •Lactose
Third level fermenting with
mucoid
• Fourthcolonies
level
• Fifth level
• Important species
include: K. pneumonaie
(indole negative) & K.
oxytoca (indole positive)
• Colonizes human colon and
upper respiratory tract
• Can be acquired
endogenous or exogenous
Special Program Students Sunday 28/10/2018
Click
to edit Master title style
DISEASES
• Edit• Master
styles outside GIT
Cause text
disease
• Second
only level
• Third level
• Community
acquired
• Fourth level
pneumonia
Lander
• Fifth level (Fried
Pneumonia)
• Neonatal sepsis
• Common cause of different
health care associated
infections (UTI, SSI, IVDRIs,
VAP*)
spp. title style
ClickProteus
to edit Master
• Highly motile (swarming
growth)text styles
• Edit Master
• •Second
level
Non lactose
fermenter
• Third level
• Have
rapid
• Fourth
levelurease activity
• Fifthmembers
level
• Important
include: P. mirabilis (indole
negative) and P. vulgaris
(indole positive)
Click to edit Master title style
instyles
human colon and environment (water and
• Edit✓Found
Master text
soil)level
• Second
• Third level
✓Can
be
acquired
endogenous
or
exogenous
• Fourth level
• Fifth
level
✓Cause
disease
outside GIT only
✓UTI (associated with urinary stone formation)
✓cause of different health care associated infections
(UTI, SSI, IVDRIs, VAP*)
Salmonella spp.
Click to edit Master title style
Non lactose,
Non sucrose fermenter
• Edit• Master
text styles
• Motile
• Second
level
Third level
• •Important
members:
• Fourth level
− S. enterica
(typhi & paratyphi serovars)
• Fifth level
− S. cholerasuis
− S. enteritidis & typhimurium
• Human is the only reservoir for S. typhi (person to person
spread)
Special Program Students Sunday 28/10/2018
DISEASES
Click to edit Master title style
• Cause diseases inside & outside GIT
• Edit Master text styles
• Enteric
• Second
level(Typhoid fever) caused by S. enterica
level suis cause bacteremia with focal lesions (including
• •S.Third
cholera
• Fourth level
osteomyelitis
and arthritis)
• Fifth level
• Enterocolitis (S. enteritidis & typhimurium)
Shigella spp.
Click to edit Master title style
• Non motile , Non lactose fermenter
• Edit Master text styles
• Reservoir:
human colon only (no
• Second
level
carriers)
•animal
Third level
• Fourth level
• Transmission:
fecal-oral spread,
• Fifth level
person to person
Cause disease inside GIT.
• Bacillary dysentery
(inflammatory bloody diarrhea)
Yersinia spp.
Click to edit Master title style
• Medically important members:
• Edit Master text styles
• Second level
−• Y.Third
pestis
level
Fourth level
− Y. •enterocolitica
• Fifth level
Transmitted from animals (zoonotic)
Y. pestis causes plague
Y. enterocoliica causes diarrhea or pseudoappendicitis (right
lower abdominal pain due to mesenteric adenitis and/ or
terminal ileitis).
Special Program Students Sunday 28/10/2018
Non- Fermenting Aerobic Gram Negative Bacilli
Click
to
edit
Master
title
style
Genus: Pseudomonas
Important properties:
• Edit Master text styles
• Theylevel
are aerobic Gram-negative motile
• Second
polar flagella . Strict aerobes.
•with
Third level
• Fourth level
• They •do
Fifthnot
level ferment sugars, they utelize
glucose by oxidation .
• They are oxidase-positive
• They produce water soluble bluish-green
exopigments (pyocyanin & pyoverdine).
32
Habitat and Transmission
Click to edit Master title style
• P. aeruginosa is widely distributed in nature
in soil, water, plants and animals.
• Edit• Master
text
styles
Also inhabits the skin, upper respiratory
• Second
tract,level
and colon of about 10% of people.
• Third level
• Its •ability
to grow in solutions has resulted
Fourth level
in contamination
of hospital respirators,
• Fifth level
humidifiers,
anesthesia
equipment,
intravenous fluids, and even distilled water.
• Pseudomonas has a remarkable ability to
withstand disinfectants and can grow in
antiseptics, and in detergents.
33
Diseases
Click
to edit: Master title style
It causes diseases in man with abnormal host defenses
• Edit(opportunistic
Master text styles
pathogen) and it is a major cause of hospital
• Second
level infections:
acquired
• Third level
• Fourth level
• Nosocomial
pneumonia (most common cause of
• Fifth level
ventilator associated pneumonia), Sepsis, and urinary
tract infections primarily in patients with lowered host
defenses.
• Chronic lower respiratory tract infections in patients with
underlying disease e.g. cystic fibrosis.
• Wound infections in sever burn patients.
34
Curved Gram Negative Bacilli
Click to edit MasterGenus:
title Vibrio
style
• This genus includes more than 30 species that are
commonly
found in aquatic environments.
• Edit Master
text styles
The level
most important Vibrio species is Vibrio cholerae; the
• •Second
agent of cholera disease.
•causative
Third level
• Another
important
member
is
V.
• Fourth level medically
• Fifth level
parahemolyticus
which causes gastroenteritis due to
consumption of fresh or under cooked see food.
Click to edit Master title style
CAMPYLOBACTER
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Important properties and species:
Click to edit Master title style
− Campylobacters
• Edit•Master
text styles
are curved, Gram-negative
rods that appear either comma or S shaped.
• Second level
• They
Third level are microaerophilic, requires 10% CO2
• Fourth
level
for
growth.
Most important species are
• Fifth level
Campylobacter
jejuni & Campylobacter coli. C.
jejuni grows well at 42°C.
• − Domestic animals such as cattle, chickens
and dogs carry the organism in their intestinal
tract and serve as a source of infection for
humans (zoonotic disease).
Click
to edithabitat
Master title style
Natural
• Edit Master text styles
• Second level
Third level
It• exist
as normal gastrointestinal tract flora of many
• Fourth level
animals
e.g.
• Fifth
level cattle, chickens, and dogs (zoonotic
disease).
Transmitted by:
Click to edit Master title style
• 1. Ingestion of contaminated food (such as undercooked
• Edit Master
textor
styles
poultry
meat) and drinks (as unpasteurized milk,
• Second
level
contaminated
water).
• Third level
• 2. •Contact
Fourth level with infected animals or animal products.
Fifth level
• They• are
common human pathogens, causing mainly:
• 1. Enteritis
• 2. Occasionally systemic infection.
• Infections of campylobacter can be complicated by
Guillain-Barré syndrome
Genus:
Helicobacter
Click to edit Master title style
-Helicobacters are curved Gram-negative rods
and appear spiral in tissue biopsies.
• Edit Master text styles
− They are microaerophilic and have rapid
• Second level
urease
activity
• Third level
• Fourth level
− H. pylori
is the causative agent of
• Fifth level
gastritis and peptic ulcer disease
-Infection with H. pylori is a risk factor for
gastric carcinoma and is linked to mucosalassociated
lymphoid
tissue
(MALT)
lymphomas.
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Click to edit Master title style
• Edit Master text styles
CLASSIFICATION AND
CHARACTERIZATION OF
MEDICALLY RELEVANT BACTERIA (3)
• Second level
• Third level
• Fourth level
• Fifth level
Dr. Wafaa khalil zaki
Prof. of Medical Microbiology & Immunology
Intended Learning Outcomes
By the end of this lecture students should be able to:
Mention the important biological properties of :
• Gram-Negative Rods Related to the Respiratory Tract: Hemophilus,
Bordetella and Legionella.
• Bacteria causing zoonotic diseases: Brucella, Pasteurella and Francisella.
• Anaerobic Gram Negative Bacilli: Bacteroides.
• Bacteria Not stained By Gram Stain: Mycobacterium and Spirochetes.
• Cell Wall Free Bacteria: Mycoplasma.
• Obligate Intracellular Bacteria: Chlamydia and Rickettsia.
Gram-Negative
Rods
Related
to
the
Respiratory
Click to edit Master title style
Tract
There text
are styles
three medically important Gram-negative rods
• Edit• Master
typically
• Second
level associated with
the respiratory tract:
level
1.• Third
Hemophilus
influenzae (H. influenza),
• Fourth level
• Fifth level pertussis (B. pertussis),
2. Bordetella
3. Legionella pneumophila (L. pneumophila).
• H. influenzae and B. pertussis are found only in humans,
whereas L. pneumophila is found primarily in
environmental water sources.
ClickGenus:
to editHemophilus
Master title style
• Edit
Master textproperties:
styles
Important
• Second level
• It• Third
is level
a group of short Gram
• Fourth level
negative
bacilli.
• Fifth level
• Requires enriched media, usually
containing
blood
or
its
derivatives, for its isolation.
(It needs growth factors called X
(Hemin) and V (NAD) factors).
Click to edit Master title style
• Edit •Master
stylesvirulent
The text
most
strains of H. influenzae
• Second level
polysaccharide capsule with six
• have
Third level a
• Fourth level
serotypes,
(a-f).
• Fifth level
• Type (b) is the most virulent.
• Other strains are not encapsulated.
ClickDiseases
to edit Master title style
H. influenzae
• Edit•Master
text styles
type b
causes
meningitis and
• Second
level
• Third level
epiglottitis
in infants and
• Fourth level
• Fifth level
children.
• Non-capsulated strains
usually
cause
non
invasive infections e.g.
otitis media and sinusitis.
First year .infection module
ClickGenus:
to editBordetella
Master title style
properties:
• EditImportant
Master text styles
• Second level
•• Gram
Third level negative coccobacilli.
• Fourth level
• Fifthimportant
level
•Most
species is:
Bordetella pertussis, the
causative agent of pertussis
(whooping cough).
Firs year. infection module
Genus:
Legionella
Click to edit Master title style
Important properties:
• Edit Master text styles
• It is a large family comprising many different
• Second level
•species.
Third level
• Fourth level
• Fifth level
• L. pneumophila
is the pathogen of greatest
medical importance.
• Legionella is a facultative intracellular
pathogen.
Diseases: Legionellosis (Legionnaire disease).
Special Program Students Sunday 28/10/2018
Click• Habitat
to editisMaster
title stylewater
in environmental
sources.
• They are
by and survive within
• Edit Master
text engulfed
styles
free-living
amoebas which act as a
• Second
level
• reservoir.
Third level
• Fourth level
Transmission:
• Fifth level
• Inhalation or aspiration of aerosols
containing the bacteria generated from
contaminated air conditioning systems,
water-cooling towers, water taps, and
showerheads.
• No person to person transmission.
Click
to edit
Master title style
Genus:
Brucella
Important properties:
• Edit Master text styles
• Brucella
• Second
levelspecies are small, coccobacillary, Gram-negative rods.
Third level
• •Morphologically
they resemble Hemophilus and Bordetella.
• Fourth level
Disease:• Fifth level
The causative agent of Brucellosis (undulant fever- Malta fever).
Transmission:
• Brucellosis is a true zoonotic disease i.e. all infections are
transmitted to humans from animals.
• No human to human infection.
Pasteurella
multocida
Click
to edit Master
title (P.multocida)
style
• Edit Master text styles
Important
properties:
• Second level
level
It• isThird
a
short,
encapsulated
Gram
negative
• Fourth level
• Fifth
level
rod that
exhibits
bipolar staining.
Transmission: The organism is part of the
normal flora in the mouths of many
animals, particularly domestic cats and
dogs, and is transmitted by biting.
Click to edit Master title style
• EditDisease:
Master text styles
• Second level
• •ItThird level
causes wound infections
• Fourth level with cat and dog bites.
associated
• Fifth level
• A rapidly spreading cellulitis at the
site of an animal bite.
• Osteomyelitis can complicate cat
bites.
First year .infection module
Anaerobic Gram Negative Bacilli
Click
to
edit
Master
title
style
Genus: Bacteroides
Important
properties:
• Edit
Master text
styles
They are
anaerobic Gram negative bacilli.
•• Second
level
• They
arelevel
part of the normal flora.
• Third
• Fourthare
level endogenous, usually arising from a
• Infections
• Fifth
break in
a level
mucosal surface, and are not
communicable.
• Bacteroides fragilis is the most frequent
pathogen.
Disease:
• Members of the genus Bacteroides are the most
common cause of serious anaerobic infections
(e.g., sepsis, peritonitis, and abscesses).
Bacteria
Not
stained
By
Gram
Stain
Click to edit Master title style
Mycobacteria
• Edit
Master text
styles
Important
properties:
• Second level
• The
most
• Third
level important characteristic of
Fourth level is the property of acidthis • genus
• Fifth level
fastness,
i.e. they are difficult to stain
because of their thick cell wall and its
high lipid content, but once stained,
they resist decolonization by acid or
alcohol and are therefore called acidfast bacilli (AFB).
Click to edit Master title style
Medically important members of the genus Mycobacteria:
• Edit Master text styles
• Second level
Mycobacterium
• Third level
tuberculosis complex
• Fourth level
(MTB),
Mycobacterium leprae
• Fifth level
Mycobacterium
tuberculosis
Tuberculosis in man.
Human is the only
reservoir.
Atypical mycobacteria
Or Mycobacteria
other than tuberculosis (MOTT)
or Non tuberculous mycobacteria
(NTM)
Leprosy
Mycobacterium
bovis
may be associated with
human disease.
Tuberculosis in cattle,
may be transmitted to man causing tuberculosis
Mycobacterium tuberculosis
Click
to
edit
Master
title
style
(M. tuberculosis)
Important properties:
• Edit Master text styles
Theylevel
are slender, straight or curved
• •Second
• Third level
rods
arranged singly or in pairs,
• Fourth level
non-motile,
non-capsulated and
• Fifth level
non-spore forming.
• They grow in parallel groups called
cords due to presence of a cord
factor (trehalose dimycolate) which
is an important virulence factor.
Special Program Students Sunday 28/10/2018
Cord
Factor
• M.
tuberculosis
grows
Click
to edit
Master title
style
slowly (i.e., it has a
doubling
time of 18 hours)
• Edit Master
text styles
• Second
level
• •Mycobacterial
cell
wall
is
Third level
characterized
by presence
• Fourth level
Fifth level
of •high
lipid content
(mycolic acids) which
permits
intracellular
survival and doesn’t allow
staining by Gram’s stain.
Mycolic
Acid
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
ZN STAIN
Click to edit Master title style
are
• Edit•They
Master text
stylesstained by Ziehl Neelsen (ZN)
• Second
level
stain.
• Third level
• Fourth level tuberculosis.
Disease:
• Fifth level
ZN stained film
Clinical
forms
of
tuberculosis:
Click to edit Master title style
• Pulmonary TB: it is the most common clinical form.
Extrapulmonary
• Edit• Master
text stylesTB: affecting other organs e.g. meninges, kidney or
bone.level
• Second
Thirdtuberculosis.
level
• •Skin
• Fourth level
• Milary• TB:
is a wide disseminated form.
Fifth it
level
Click to edit Master title style
of styles
transmission:
• EditMode
Master text
• Second level
by
air borne particles that arise from patients
• Third level
level
with• Fourth
open
pulmonary
tuberculosis
or
skin
• Fifth level
lesions.
Click
to
edit
Master
title
style
Mycobacterium leprae
• Edit Master text styles
Important
properties:
• Second level
Third level
• •Acid
fast bacillus non motile non
• Fourth level
capsulated
• Fifth level and non-spore forming.
• A primary human pathogen.
• M. leprae has not been grown in the
laboratory; either on artificial media
or in cell culture.
Special Program Students Sunday 28/10/2018
•
The
optimal
temperature
for
growth
(30°C)
is
Clicklower
to edit
Master
title
style
than body temperature.
Disease:
Leprosy
• Edit
Master text
styles in man.
••Second
level granulomatous disease affecting the
A chronic
• Third mucous
level
skin,
membrane, and peripheral nerves
• Fourth level
(the lesions
• Fifth level involve the cooler tissues of the
body).
Mode of transmission of leprosy:
• Infection is acquired by prolonged contact with
patients with lepromatous leprosy, who discharge
M. leprae in large numbers in nasal secretions
and from skin lesions.
Special Program Students Sunday 28/10/2018
The face of a
man with
active
lepromatous
leprosy
Disease
Click to edit Master title style
cell
• EditThe
Master
textmediated
styles
immunity of the patients defines
the clinicopathological
picture which are Tuberculoid
• Second
level
• Thirdof
levelleprosy and Lepromatous type of Leprosy:
type
• Fourth level
• Fifth level
• Tuberculoid
type: This is the mild form of leprosy in
which cell mediated immunity (CMI) is intact.
• Lepromatous type: It is the severe form of the
disease in which CMI is depressed. Therefore, M.
leprae grows in the skin and superficial nerves
Special Program Students Sunday 28/10/2018
Spirochetes
Click to edit Master title style
Heterogeneous group of spiral motile
• Editbacteria.
Master text styles
• Second level
• They
include 3 genera:
• Third level
• Fourth level
1. Treponema
pallidum (T. pallidum) causes
• Fifth level
syphilis (STD).
2. Leptospira: Cause leptospirosis, a zoonotic
disease transmitted by animal urine in water.
3. Borrelia: Cause Lyme disease (Borrelia
burgdorferi) and relapsing fever (other
Borrelia species).
Special Program Students Sunday 28/10/2018
Cell Wall Free Bacteria
ClickMycoplasma
to edit Master title style
General characters :
• Edit
Master
text styles
• The
smallest
free-living organisms.
• Second level
• Prokaryotic
cells resemble Gram
• Third level
negative
• Fourthbacteria.
level
• Fifth level
• Their outer surface is a flexible cell
membrane containing cholesterol but
lack a cell wall.
• So, these organisms can assume a
variety of shapes (pleomorphic).
Click to edit Master title style
• Stain poorly with Gram
• Edit Master
styles
stain, text
but
stain well with
• Second
level
Giemsa’s
stain or Leishman
• Third level
stain.
• Fourth level
level
• Are • Fifthnot
sensitive
to
antibiotics that act on cell
wall e.g. ᵝ-lactam antibiotics.
• Are not destroyed by
lysozymes.
Giemsa’s stain
Click to edit Master title style
specie associated with human disease:
• EditThree
Mastermycoplasma
text styles
• Second
level
• Mycoplasma
• Third level
pneumoniae: which is the cause of atypical
pneumonia.
• Fourth level
• Fifth level
• Mycoplasma
hominis: has been implicated as an
infrequent cause of pelvic inflammatory disease.
• Ureaplasma urealyticum: may cause approximately 20% of
cases of nongonococcal urethritis.
Obligate
Click to edit
MasterIntracellular
title style Bacteria
Chlamydia
• EditGenus:
Master text
styles
General
• Second
levelCharacters:
Third level
• •Non
motile coccoid bacteria.
• Fourth level
• Fifthobligate
level
• They are
intracellular pathogen because:
They lack the ability to produce sufficient energy and cannot
synthesize ATP to grow independently and therefore can
grow only inside host cells.
• Don’t grow on artificial bacteria culture media.
• Grow on yolk sac of chick embryo or in tissue culture.
Click
to editcaused
Master
style
Disease
bytitle
Chlamydia:
• EditChlamydia
Master text trachomatis:
styles
• Second
level
• Types
A,
B, Ba, and C: cause Trachoma.
• Third level
• Types
D–K:
• Fourth
level cause inclusion conjunctivitis & nongonococcal
• Fifth level
urethritis.
• Types L1-L3: cause Lymphogranuloma venereum.
Chlamydia pneumoniae causes atypical pneumonia.
Chlamydia psittaci causes psittacosis (atypical pneumonia).
Click
to edit
Master title style
Genus:
Rickettsia
General Characters:
• Edit Master text styles
• Small,
aerobic, coccobacilli.
• Second
level
Third level intracellular parasites of eukaryotic cells.
• •Obligate
• Fourth level
• May reside
in the cytoplasm or within the nucleus of the cell that
• Fifth level
they invade.
• Have typical Gram-negative cell walls.
• All are maintained in animal & arthropod reservoirs.
• Transmitted by arthropod vectors (e.g., ticks, mites, lice or fleas).
• Humans are accidentally infected.
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
General Mycology
Intended Learning Outcomes (ILOs)
1. Explain the eukaryotic nature of the fungi.
2. Define: fungal spores, yeast, filamentous fungi, dimorphic fungi, and other
scientific terminology peculiar to mycology
3. Explain how fungi cause diseases.
4. Correlate the peculiar structures in fugal cells and mode of action of antifungal agents
5. Discuss the basis of classification of medically-important fungi.
6. Outline the underlying mechanisms of antifungal resistance
General Characters of Fungi
•Eukaryotic cells that have a true
nuclei
•Devoid of chlorophyll
•Can absorb all nutrients from the
environment specially decaying matter
•Grow better at acidic pH
Eukaryotic
Prokaryotic
Example
Fungi, human cell
bacteria
Nuclear material
True nucleus
Nuclear membrane
Nucleoli
Multiple chromosome
Histones
Single chromosome
No histones
Mitosis
Simple binary fission
Division
Cytoplasmic structure
Mitochondria
Microtubular cytoskeleton
RES
Ribosome :
80S
Absent
Absent
70S
Cytoplasmic membrane
Contains sterol
No mesosomes
Contain lipoprotein
No sterol
Mesosome
lipoprotein
Cell Wall
fungi contain chitin, mannan,
glucan
Present (except mycoplasma)
©
Fungi are present as
• Saprophytes in nature: Most species are beneficial. They are essential in breaking
down and recycling organic matter. Some fungi greatly enhance the quality of life by
contributing in production of food as bread and cheese. Other fungi produce useful
bioactive metabolites as antibiotics (e.g penicillin) and cytotoxic drugs as cyclosporine
• Commensal: Live in harmony on humans, driving their nutrition from compounds on
body surfaces. Some are opportunistic under certain conditions they may invade
tissues or vasculature and cause disease
• Pathogenic: Infect the healthy and cause severe disease in the immunocompromised
•There are over 100,000 species recognized, with 100
infectious agents to humans.
•Moulds are composed of numerous, microscopic,
branching hyphae known collectively as a mycelium.
•Yeasts are composed of fungal cells giving the appearance
of smooth colonies
•Dimorphic fungi
©
Fungal spores:
• Fungal spores are microscopic biological particles forming a part
of the life cycle of fungi, allowing fungi to be reproduced. Like
bacterial spores, they have an enhanced survival value and
structural features that promote spread.
•Airborne fungal spores are one of the major causes of
respiratory illness in humans.
• The presence/absence of spores and their size, shape and
location are major features used in the laboratory to identify the
species of fungus in clinical specimens.
Overview of fungal diseases
Fungi may cause diseases by one of the following mechanisms:
1- Allergies: Many fungal spores contain allergens which can
trigger a range of respiratory symptoms in those susceptible,
including sneezing, runny nose, mucous production, cough,
congestion, sinusitis, earache, headache, and wheezing.
2- Mycotoxicosis
• Mycotoxins are secondary metabolites produced by fungi and are capable
of producing diseases.
• The mycotoxicosis is a food poisoning caused by ingestion of food
containing a sufficient quantity of mycotoxins. Mycotoxicoses, like all
toxicological syndromes, can be acute with rapid onset or chronic
characterized by low-dose exposure over a long time period, resulting in
cancers and other generally irreversible effects.
• Chronic intoxication occurs worldwide, but especially in climates with
high temperature and humidity and where grain is harvested with high
water content.
QUIZ
Regarding the structure and reproduction of fungi, which one of the
following is most accurate?
(A) Peptidoglycan is an important component of the cell wall of fungi.
(B) Molds are fungi that grow as single cells and reproduce by budding.
(C) Some fungi are dimorphic (i.e., they are yeasts at room temperature and
molds at body temperature).
(D) The fungal cell membrane contains ergosterol, whereas the human cell
membrane contains cholesterol.
(E) As most fungi are anaerobic, they should be cultured under anaerobic
conditions in the clinical laboratory.
• Mycoses : disease caused by infection
with a fungus that may cause superficial,
cutaneous, subcutaneous, or systemic
diseases :
a. Superficial skin infections: Infections in
stratum corneum
b. Cutaneous mycosis: Involves keratinized
tissues as skin, nail and hair,
c. Subcutaneous mycosis: Mycosis of the
subcutaneous tissues and adjacent bones
d. Systemic mycosis: Starting as primary
pulmonary lesions that may disseminate to
any organ
• An antifungal drug is the drug that selectively eliminates fungal
pathogen from a host with minimal toxicity.
• As fungi are eukaryotic and their ribosomes and many pathways
resemble those of humans, unique fungal pathways have to be
targeted
Available classes of antifungal drugs:
A-Interfere with cell membrane synthesis e,g Polyenes, azoles and
alayllamines
B- Interfere with cell wall synthesis e.g Echinocandins
C-Interfere with nucleic acid synthesis e.g Flucytosine
D-Miscellaneous (nucleic acid, cell membrane synthesis) e.g
Grieseofulvin
I-Antifungal drugs interfering with cell membrane synthesis
Polyenes: fungicidal with poor gastrointestinal absorption. bind
ergosterol in fungal cell membrane creating ion channels leading to
leakage and cell death. Polyenes bind to less extent to cholesterol the
predominant sterol in mammalian cell membranes. They are thus toxic.
Amphotericin B: administered intravenously for serious systemic fungal
infection caused by yeasts, molds or dimorphs but Penetration of joints
and CSF is poor
Nystatin: used topically to treat fungal infection in skin, vagina and oral
cavity.
• Azoles:
The azoles are fungistatic against yeast and fungicidal against molds.
Azoles inhibit P450 enzymes needed for the synthesis of ergosterol of the
cell membrane and interfere with membrane integrity.
They are either topically applied in skin or mucosal infections e.g
miconazole or orally administered in non life threatening conditions e,g
Ketoconazole
3-Triazoles: Azole drugs with three nitrogens in azole ring. They have
broder spectrum and better systemic activity than azoles. Examples
Fluconazole, Itraconazole, Voriconazole used in systemic infection
• Allylamines:
Alylamines e.g terbifunates inhibit squalene epoxidase, another
enzyme required for ergosterol synthesis .This is an earlier step in
the ergosterol biosynthesis than the azole class of antifungal
drugs. This inhibition leads to cell membrane fragility, increased
membrane permeability, and intracellular accumulation of sterol
precursors.
They have both fugistatic and fungicidal activity
II. Antifungal drugs interfere with cell wall synthesis:
1-Echinocandins: fungicidal drugs, inhibit fungal glucan synthesis leading to weakened cell
wall and cell lysis e.g caspofungin
III. Antifungal drugs acting on nucleic acid
Flucytosine (5-fluorocytosine): An oral fungistatic agent. It is converted in fungal cell to 5
fluorouradylic acid which competes with uracil leading to miscoding and disruption of
RNA, protein and DNA synthesis. Because resistance quickly develops if used alone, it is
used in combination with other antifungal drugs. It penetrates well into all tissues
including cerebrospinal fluid
IV. Miscellaneous:
Griesofulvin; a fungistatic drug, orally administered. It is thought to inhibit fungal cell
mitosis by inhibiting tubulin formation and nuclear acid synthesis.
QUIZ
Regarding the mode of action of antifungal drugs, which one of the
following is most accurate?
(A) Azole drugs, such as fluconazole, act by inhibiting ergosterol synthesis.
(B) Amphotericin B acts by inhibiting fungal protein syntheses at the 40S
ribosomal subunit.
(C) Terbinafine acts by inhibiting fungal DNA synthesis but has no effect on
DNA synthesis in human cells.
(D) Echinocandins, such as caspofungin, act by inhibiting messenger RNA
synthesis in yeasts but not in molds.
Antifungal resistance
 Primary resistance: naturally among certain
fungi without prior exposure to the drug.
e.g. resistance of Candida krusei to
fluconazole .
 Secondary resistance: among previously
susceptible strains after exposure to the
antifungal agent depends on altered gene
expression (mutation)
e.g. growing
resistance of Candida albicans and Candida
glabrata
to first-line and second-line
antifungal medications, namely, fluconazole
and echinocandins
Plasmid , transposon
Drug inactivation
More than one
mechanism of resistance
to the drug can be
functioning in any given
fungal strain with
additive effects
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
• Fourth level
• Fifth level
Presented
by
DR . Makram F. Attalah
Professor of Medical Microbiology &
Immunology,
Faculty of Medicine, Ain Shams University
1
1
Contents
• HAIs: definition, sources, predisposing factors, chain of
infection
• Standard Precautions
• Transmission based isolation precautions
• Aseptic techniques and Safe injection practices
• Basics of personnel health components of occupational
safety
2
Intended Learning Outcomes (ILOs)
•
•
•
•
•
•
•
•
•
•
•
•
Define Health Care Associated Infections (HAI).
Illustrate components of the chain of infection.
Describe components of standard precautions.
Apply different types of hand hygiene properly at proper situations.
Identify indications for the use of personal protective equipment.
Mention level of processing soiled patients care equipment.
Identify types of waste in health care.
Differentiate between different transmissions based isolation precautions.
Describe basic principles of safe injections.
Identify key processes of aseptic techniques.
Recognize elements of health care personnel (HCP) safety.
Demonstrate proper response to sharp injury and/ or accidental exposure to
blood borne pathogens.
3
4
Healthcare associated infections (HCAIs)
(Nosocomial or hospital acquired)
▪Infections acquired during health care in any
health care facility
▪Not present or incubating at admission
▪Usually occurring more than 48 hours after
admission
5
Chain of Infection
Bacteria
Virus
Fungus
No effective
resistance to a
particular
pathogenic agent
Patient
HCP
Equipment
Environment
Mucous membranes
Broken skin
Contact
Droplet
IPC
Airborne
•
•
•
•
Blood & Body fluid
Respiratory droplets
gastrointestinal tract: stool
Genitourinary tracts: semen,
vaginal secretion.
6
Endogenous (self- infection)
It is caused by permanent or transient flora of the
patient:
• Transmission to sites outside normal habitat
• Damage to tissue and impairment of primary defense
mechanisms (e.g. surgical procedures)
• Inappropriate antibiotic therapy (e.g. antibiotic
associated diarrhea)
7
Exogenous
• Other patients: either directly or through contaminated hands of
healthcare personnel (cross infection).
• Healthcare personnel (HCP) : if they are infected or colonized with
virulent organisms
• Contaminated instruments
• Environment: contaminated surfaces, air or water.
8
Modes of Transmission
•Contact
•Droplet
•Airborne
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Direct Contact
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Indirect Contact
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Droplet
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Air-Borne
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Predisposing Factors
• Impairment of general host defense
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Predisposing factors (cont.)
• Impairment of local host defense
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Preventive Strategy
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Standard Precautions
• They are a standard of care designed to reduce the risk of transmission
of microorganisms from both recognized and unrecognized sources of
infection in health care facilities.
• They are applied to ALL patients.
• They are designed
to
protect healthcare personnel,
patients, visitors, and environment from pathogens that can be
spread by:
• Blood.
• All body fluids, secretions, and excretions regardless of whether they contain
blood (potentially infectious material).
• Mucous membranes.
• Non-intact skin.
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Standard Precautions include
• Hand Hygiene
• Personal Protective Equipment (PPE) (e.g. gloves, gowns,
masks, eye goggles and face shields)
• Proper handling and processing of patient care
equipment
• Environmental surfaces control
• Respiratory hygiene
• Safe injection
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Hand Hygiene: a general term
➢ Hand washing
➢ Hand Antisepsis
✓ Antiseptic hand wash
✓Antiseptic hand rub
➢ Surgical hand antisepsis.
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Hand Antisepsis
Hand Rub
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Antiseptic hand wash
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Alcohol Rub
• Alcohol rub is a rapid method
for hand antisepsis
• It is an antiseptic NOT cleaner
• Should NOT be used when
hands are contaminated with
visible dirt, blood or mucous
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Alcohol rub
Easily accessible at the
point-of-care
Individual pocket
bottles carried by all
health-care workers.
Bottles fixed to the
patient’s bed or
bedside table (or
around this area).
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Indications of Hand Washing
• Hands are visibly dirty or
contaminated with proteinaceous
material, or visibly soiled with
blood or other body fluids,
• Exposure to potential sporeforming organisms
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Hand rub
• If hands are not visibly soiled, use an alcohol
based hand rub for routine hand antisepsis
The 5 Moments for HH
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When?
The 5 moments for HH
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How?
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Steps of Hand Washing
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Alcohol Rub
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Gloves
Types of gloves:
• Clean disposable non
sterile gloves.
• Surgical sterile gloves.
• Utility, heavy duty
gloves.
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Masks, eye protection, face shields
Protection of HCWs
• worn when there is risk of splashes or
sprays of blood or body fluids into the face
and eyes of health care workers (HCWs).
(standard precautions)
• Protection from microorganisms that are
transmitted by droplets e.g.
• Neisseria meningitidis,
•Bordetella pertussis.
(droplet precautions)
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Surgical standard mask
Protection of patients
• Trapping droplets from the wearer’s exhaled breath:
to provide patient protection in the O.R.
• They are worn by HCP when performing spinal
procedures (e.g., lumbar punctures, myelogram, and
spinal anesthesia) or inserting a Central Vascular
Catheter (CVC); to protect patients from exposure to
infectious agents carried in a healthcare worker’s
mouth or nose.
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Face mask worn by the patient
• Surgical mask is worn by coughing or sneezing
patient to limit potential dissemination of infectious
respiratory secretions from the patient to others
(Respiratory Hygiene/Cough Etiquette).
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High Efficiency Masks (Respirator)
• Designed to capture high percentages (>95%) of
particles that are less than 5 micron in size
•
Protection of health care worker from airborne
infectious agents such as Mycobacterium
tuberculosis.
• Also by HSCT patients when urgenly brought
outside protective environment to prevent
exposure to fungal spores
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Respirator
)N95 or FFP2(
35
Gowns and Aprons
Clean Gown
Sterile Gown
• Protect HCWs against splashes
of blood or body fluids.
(standard precautions)
• Asepsis in OR or inserting
central lines (together with
sterile gloves, standard face
mask and head caps (
maximal sterile barriers)
• Prevent infection transmission
through contact (contact
isolation precautions)
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Caps
• To confine and contain hair during invasive procedures and inside
OR
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Protective Foot Wear
(Leg coverings, boots)
Closed footwear replacing the ordinary shoes is not
generally needed with the exception of some
special areas such as: the Operating Room (OR)
Fluid resistant closed foot wear is needed during
waste management, environmental cleaning, and
cleaning surgical instruments; to protect HCP
from skin exposure to blood, body fluids and
sharp objects like needles and syringes
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Patient Care Equipment
• Single use: proper disposal
• Reusable: proper processing
2
➢ Cleaning
➢ Disinfection
➢ Sterilization
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Classification of patient care equipment
(Spaulding classification)
•Items of high risk
•Items of intermediate risk
•Items of low risk
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Items of high risk
• Penetrate sterile tissues, including body cavities and the vascular
system, e.g. surgical instruments, intra-uterine devices, vascular
catheters.
2
• Single use (disposable)
• Reusable:
Cleaning followed by sterilization
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Items of intermediate risk
• Equipment that does not penetrate the skin or
enter sterile areas of the body but is in contact
with intact mucous membranes or non-intact
skin
• Items contaminated with virulent or
transmissible organisms
• Cleaning followed by disinfection
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Items of low risk
• Items in contact with intact skin, or the inanimate
environment not in contact with the patient
• Noncritical patient care items: e.g. stethoscope, blood
pressure cuffs
• Noncritical environmental surfaces e.g. bed rails,
some food utensils, bedside tables, patient furniture
and floors.
• Cleaning and drying is usually adequate.
• Disinfection when indicated.
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Environmental Surfaces
House Keeping Surfaces
Clinical Contact Surfaces
• Wet Cleaning (no dry sweeping)
• Spot disinfection (1/50 of 5% chlorine)
• Decontamination of blood and OPIFs
(1/10 of chlorine 5%
Cleaning & Disinfection
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To sum up
• HAIs are common adverse effects in all health care levels
• Preventive strategy relies upon adherence to standard and
transmission based isolation precautions
• Aseptic techniques are basis for patient safety in invasive clinical
procedures
• HCP safety depends on vaccination, prevent exposure and proper
management of exposure events
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• Edit Master text styles
• Second level
• Third level
Most welcome for any question
• Fourth level
• Fifth level
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• Second level
• Third level
• Fourth level
• Fifth level
Presented
by
DR . Makram F. Attalah
Professor of Medical Microbiology &
Immunology,
Faculty of Medicine, Ain Shams University
1
Contents
• HAIs: definition, sources, predisposing factors, chain of
infection
• Standard Precautions
• Transmission based isolation precautions
• Aseptic techniques and Safe injection practices
• Basics of personnel health components of occupational
safety
2
Intended Learning Outcomes (ILOs)
• Identify types of waste in health care.
• Differentiate between different transmissions based
isolation precautions.
• Describe basic principles of safe injections.
• Identify key processes of aseptic techniques.
• Recognize elements of health care personnel (HCP)
safety.
• Demonstrate proper response to sharp injury and/ or
accidental exposure to blood borne pathogens.
3
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Safe waste disposal
• Segregation at work place (sharp waste & infectious or regulated
medical waste)
• Color coding of receptacles
• Puncture-resistant containers with a lid for sharp waste
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Infectious or regulated medical waste
• Fluid waste (Blood & body fluids ).
• Contaminated items with blood or other potentially
infectious materials e.g. contaminated dressings.
• Microbiology laboratory waste e.g. stock cultures,
discarded diagnostic samples (e.g. urine, stool).
• Pathological and anatomical waste.
• Sharps e.g. used syringes, needles, disposable scalpels and
blades.
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Respiratory Hygiene
• It applies to any person with signs of illness
including cough, congestion, rhinorrhea, or
increased production of respiratory secretions
when entering a healthcare facility.
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Source Control Measures
• Cover your nose and mouth with a tissue
when you cough or sneeze
• Throw the tissue in the trash
• Wash your hands
• Wear surgical mask if tolerated or
maintain spatial separation, >3 feet
if possible
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10
Safe Injection Practices
• What is safe injection???
•
It is a set of measures taken to perform injections in
an optimally safe manner for patients, healthcare
personnel, and others
11
12
Safe Injection practices
• Use a sterile syringe and needle for each injection, dispose appropriately
after use in approved puncture resistant container for sharps disposal.
•
Never use medication in a syringe for more than one patient even if the
needle is changed between patients. Changing the needle but not the
syringe is unacceptable.
•
Do not keep multi-dose vials in the immediate patient treatment area; store
in accordance with the manufacture’s recommendations; discard if sterility
is compromised or questionable.
• Check the vial for leaks or cracks.
13
Safe Injection practices (cont.)
• The vial access diaphragm should be disinfected with an
approved disinfectant (70% alcohol) immediately prior to
accessing.
•
•
Always use a new needle and syringe every time fluid is
withdrawn from a multidose vial.
Never leave one needle inserted in the vial cap for multiple
uses.
• Expired medications should be discarded.
14
Proper handling of multi dose vials
1. Keep it in a clean place outside patient treatment are
2. It should be labeled with opening date and expiry date
3. Before use: Check the vial for leaks or cracks
4. Prior to access: Disinfect the vial access diaphragm with 70%
alcohol
5. Always use a new needle and syringe every time fluid is
withdrawn from a multidose vial
6. Never leave an inserted needle in a multidose vial
15
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Aseptic techniques
• Aseptic Technique is a general term involving practices that
minimize the transmission of micro-organisms during invasive
procedures
• Invasive procedures
• Surgical procedures
• The placement of device into sterile body spaces such as
intravenous lines and Urinary catheters.
• Wound care
• Intravenous or intramuscular injection
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Key processes for performing Aseptic Techniques
• Hand antisepsis
• Patient skin antisepsis
• No-touch-technique
• Suitable attire (head cap, mask, strile gown, sterile
gloves)
• Sterile drapes
• Maintaining sterile field during surgical procedures
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Clean no touch technique
Insertion of PVC
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Transmission Based Isolation
Precautions
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Transmission based precautions
•Contact precautions
•Droplet precautions
•Air borne precautions
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Contact precautions
• Applied for patients infected or colonized with microorganisms
transmitted by direct or indirect contact
Examples :
• Skin Infections: impetigo, scabies, pediculosis
• Respiratory syncytial virus.
• Disseminated herpes simplex, Zoster
• MRSA, VRE and multi drug resistant Gram negative bacteria.
• Clostridium difficile associated diseases.
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Requirements of Contact precautions
In addition to standard precautions
• Single room if available
• En-suite toilet and HW basin
• Clean gloves and clean gowns during any patient
contact
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Droplet precautions
Applied for patients with infections transmitted by large Droplets
Examples:
• Influenza
• Rubella
• Meningococcal meningitis
• Streptococcal pharyngitis
• Multi-drug resistance pneumococcal pneumonia
• Pneumonic plague
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Requirements of droplet precautions
In addition to standard precautions
• Single room if available
• En-suite toilet and HW basin
• A standard surgical mask should be worn before entering the
room or being within one meter from the patient
• Limit patient movement to essential purposes
• Patient can put a surgical standard mask while being outside
the isolation room
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Airborne precautions
Applied for air borne transmitted infections
e.g.
• Tuberculosis
• Measles
• Varicella-Zoster
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Requirements of airborne precautions
• A single room with
negative air flow
ventilation
• A high efficiency mask
should be worn before
entering the room.
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Requirements of airborne precautions
• En suite toilet and a basin for hand washing.
• The door of the room should be kept closed except during
necessary entrances and exits.
• The patient transport outside isolation room should be
limited to essential purposes
• Patient can put a surgical mask while being outside the
isolation room
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Protective environment
• Applied for allogeneic hematopoietic stem cell transplants (BM
transplantation)
• Provide engineering controls to prevent exposure to environmental
fungal spores
• What is the significance of protective environment?
• Give reasons: HSCT patients are placed in protective environment
in high risk period following transplantation?
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Requirements of Protective environment
•What are the components of protective
environment?
•Positive room air pressure
•HEPA filtration of incoming air
•12 or more air changes per hour.
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Positive air pressure room
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Risk of blood borne pathogens
• Blood borne pathogens include:
• HBV
• HCV
• HIV
• They are often carried by persons
unaware of their infection.
• They can produce chronic infection
and dangerous complications
• Needle stick and other sharp
injuries represent the greatest risk
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Safety Program
• Education and Training
• Immunization
• Exposure Prevention
• Exposure Management
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HCW Immunization
• Hepatitis B vaccine: (3-dose vaccine series administered intramuscularly
at 0, 1, and 6 months).
• Influenza vaccine (annual vaccine)
• Measles, Mumps and Rubella vaccines (MMR).
• Varicella-zoster (VZV).
• Tetanus, diphtheria and acellular pertussis(Tdap).
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Pre-exposure management (for HBV)
•
Pre-exposure evaluation for health-care
personnel previously vaccinated with
complete (≥3dose) HepB vaccine series who
have not had postvaccination serologic testing
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Measure anti-HBs Antibody Level
< 10 mIU/mL
≥ 10 mIU/mL
Administer ONE dose of HB vaccine & re
measure anti-Hbs antibodies 1 month later
< 10 mIU/mL
≥ 10 mIU/mL
Administer TWO dose of HB vaccine & re
measure anti-Hbs antibodies 1 month after last
dose
< 10 mIU/mL
Evaluate after every
exposure
≥ 10 mIU/mL
No action for
prophylaxis against
HBV exposure
regardless of source
patient
Prevent sharp injuries
• Be careful with sharp instruments
• Do not recap by two hands
• Do not dispose in plastic bags
• Dispose in puncture resistant container
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Sharps disposal and handling
√
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Prevent mucous membrane exposure
• Appropriate PPE
• Use mouthpieces, resuscitation bags when
needed
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Exposure Management
• IMMEDIATE response
• REPORTING
• TESTING of source patient (if applicable).
• Specific viruses measures
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Immediate Response
• Skin wounds should be cleaned with soap and
water.
• Mucous membranes should be flushed thoroughly
with water.
• Eyes should be irrigated with normal saline.
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Immediate response to exposure incidents
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Importance of reporting exposure incidents
(Give reasons)
• Assess infection risk according to:
• Type and severity of exposure: e.g. percutaneous or mucous
membrane.
• Type and amount fluid exposure e.g blood or body fluid.
• Administer post exposure prophylaxis (PEP) if indicated.
• Allow follow up for the exposed HCP.
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Management of exposures to specific viruses
• Any blood or body fluid exposure to an unvaccinated person should
lead to initiation of the hepatitis B vaccine series.
•
Further management of exposure to HBV depends on the HB
vaccination status and the vaccine response status of the exposed
personnel.
•
Postexposure management of exposure to HCV is intended to achieve
early identification of infection by base line and follow up testing.
• HCP exposed to HIV should be evaluated within hours after exposure
for administration of antiretroviral medications as soon as possible after
exposure within 72 hours (preferable 24 hours)
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To sum up
• HAIs are common adverse effects in all health care levels
• Preventive strategy relies upon adherence to standard and
transmission based isolation precautions
• Aseptic techniques are basis for patient safety in invasive clinical
procedures
• HCP safety depends on vaccination, prevent exposure and proper
management of exposure events
4/2021
IPC
49
Click to edit Master title style
• Edit Master text styles
• Second level
• Third level
Most welcome for any question
• Fourth level
• Fifth level
4/2021
IPC
93