What we don’t see CAN kill us!
 Also
called microbes
 Cannot be seen without a microscope
 May be non-pathogen or pathogen
depending on where it is in body
 Aerobes
are a variety of bacteria that
require oxygen to grow.
 Anaerobes are bacteria that grow in the
absence of oxygen and are destroyed by
oxygen.
 Facultative anaerobes are organisms that
can grow in either the presence or the
absence of oxygen.
 Endogenous-
originates inside the body
 Exogenous-originates
outside the body
 Nosocomial-
infection obtained in a health
care facility (Ex: MRSA)
 Opportunistic-
is down
occurs when host resistance
 Single
cell
 3 types: Cocci, Bacilli, Spirilla
 Round
shaped
 Micrococci-
single cell
 Diplococci-two
celled
 Staphylococci-clustered
 Streptococci-
in chains
 “Strep
throat”
 Scarlet Fever
 Rheumatic fever
 “Flesh eating” disease
 Endocarditis
 Pneumonia
 MRSA
 Toxic Shock
 Rod
Shaped
 May have flagella that help the bacteria to
move
 Often produce spores
 Occur singly, in pairs
or in chains

Many produce poisons
called toxins
 Some
bacteria change into the most
resistant form of life known called spores.
 Bacteria remain alive in the spore form
but are inactive.
 They can survive extremes of heat and
dryness and even the presence of
disinfectants and radiation.
 Anthrax
 Leprosy
 Tuberculosis
 Tetanus
 Botulism
 Diphteria
 Typhoid
 Spiral
shaped
 May be other “unusual” shapes
 Example: syphilis and cholera
 The
rickettsiae are short, nonmovable rods
that normally live in the intestinal tract of
insects such as lice, fleas, ticks, and
mosquitoes.
 They are very small and require host cells to
reproduce.
 Diseases caused by rickettsiae include typhus
and Rocky Mountain spotted fever.
 These diseases are transmitted to humans by
way of the bite of an infected insect.
 Smallest
of all bacteria
 Originally thought to be a virus
 Gram
staining requires crystal violet dye,
iodine solution, alcohol solution, and a
safranin dye be used in a certain order.
 The bacteria that are stained by the dye
are classified as Gram-positive. (They
appear dark purple under the
microscope.)
 Gram negative bacteria will appear pink.
 Bacteria that are positive but stain as
negative are called Gram variable or
there’s mixed colored staining.
 Algae
range from microscopic single-cell
organisms to larger multiple-cell organisms
such as seaweed and kelp.
 All algae contain chlorophyll, as well as
pigments that cause them to appear yellowgreen, brown, or red.
 Algae are found in abundance in both
freshwater and marine habitats.
 Most algae do not produce human disease.
Red Tide
 One
celled animal-like, may contain flagella
 Often found in decayed materials, animal
feces, and contaminated water
 Cause malaria, dysentery (severe diarrhea),
and African sleeping sickness
 Not too common in the US
 Fungi
are plants, such as mushrooms, yeasts,
and molds, that lack chlorophyll.
 Diseases include athlete’s foot, vaginitis,
“Jock itch”, and ringworm
 Multi-cellular
worms or flukes
 Can be injected in food or obtained when
bitten by a mosquito
 Examples: pinworms, hookworms, trichinella
spiralis, tapeworms
 Viruses
are smallest of all microbes and
only seen with electron microscope.
 Viruses can live and multiply only inside
an appropriate host cell.
 A virus invades a host cell, copies itself,
and then destroys the host cell so the
viruses are released into the body.
 Spread from human to human through
body secretions
 HIV
 Common
cold
 Influenza- Ex:H1N1
 HPV- Human Papilloma Virus
 Polio
 Chickenpox
 Herpes



Zoster- shingles
Simplex Type 1- cold sores
Simplex Type 2- genital herpes

Hepatitis

HAV
HBV
HCV
HDV
HEV
HGV


Vowels: Food and Fecal Borne
Consonants: Blood Borne





 Infectious
agent composed of primarily
protein that is misfolded
 Must reproduce inside a host cell
 Gets the other proteins to misfold as well
 Prions
are responsible for “mad cow” disease
and possibly Alzheimer disease.
 Prion-caused diseases have been found in
human beings and animals.
 Prions are highly resistant to heat, chemical
agents, and irradiation.
 There is no treatment or vaccine against
prion diseases, and the only preventive
measure is not eating suspect food.
Microorganisms
Viruses
Protozoas
Algae
Fungi Helminths Prions
Bacteria
Cocci
Micrococci
Diplococci
Staphylococci
Streptococci
Bacilli
Rickettsiae
Chlamydia
Spirilla