Topic: Antimicrobials
Presented by: Adeela Hussain
12-10403
BIOT: 412
Antimicrobial Therapy
• Antimicrobials???
• Use of these Antimicrobials to treat diseases
Antimicrobial Therapy
Categorized as:
Empiric
Infecting
organism not
yet identified(
i.e. specific
organism)
Broad
Spectrum
Definitive
Infecting
organism
identified
Specific
Therapy
Prophylactic
Prevent
previous
infection or its
recurrence
after infection
Preventive
Narrow
Spectrum
What do we need to know to treat
with Antimicrobials???
Know the Drug
Know the Microbiology
Know the Patient
What do we need to know to treat
with Antimicrobials???
Know the drug
Know the
microbiology
Know the
patient
• Antimicrobials
• Classification according to their mode of action
• Culture results----Susceptible, Intermediate, or
Resistant
• Minimum inhibitory concentration
• Specificity
• Drug’s Activity
• Dose and route of administration
• Allergy
• Age
• Pregnancy
• Genetic and metabolic abnormalities
• Renal and hepatic function
Attributes of an Ideal Antimicrobial Agent
• Solubility in body fluids
• Selective toxicity
• Toxicity not easily altered within the host (both so
that toxicity to pathogen does not decrease and so
that toxicity to host does not increase)
• Non allergenic
• Stability within body fluids (preferably over many
hours such that dosing need not be repeated too
often)
• Resistance not easily acquired
• Stability on shelf
• Reasonable cost and availability
Antimicrobial Selection
The ability of an antimicrobial to harm a
pathogen without harming the host is termed
selective toxicity.
Higher selective toxicity-Higher Therapeutic
index
Antimicrobial Resistance
Antimicrobial agents are considered "miracle
drugs" that are our leading weapons in the
treatment of infectious diseases. But……..
Antimicrobial resistance is the ability of certain
microorganisms to withstand attack by
antimicrobials, and the uncontrolled rise in
resistant pathogens threatens lives and wastes
limited healthcare resources.
Mechanism of Resistance
• Some have innate resistance-----lack a target
site
• Some Acquire resistance by
Altered target site
Altered uptake
Antimicrobial inactivating enzymes
Mechanism of Resistance
• Resistance spreads in bacteria in three ways:
Conjugation
Transformation
Transduction
Antifungals
• An antifungal medication is a medication used
to treat fungal infections such as
athlete's foot,
ringworm,
candidiasis (thrush),
serious systemic infections such
as cryptococcal meningitis,
and others.
Some Common Examples
•
•
•
•
•
•
Imidazoles
Triazoles
Thiazoles
AllylAmines
Echinicandins
And many others
Mechanism of Action
• Antifungals work by exploiting differences between
mammalian and fungal cells to kill the fungal
organism without dangerous effects on the host.
• Unlike bacteria, both fungi and humans are
eukaryotes. Thus fungal and human cells are similar
at the molecular level. This makes it more difficult to
find or design drugs that target fungi without
affecting human cells.
• As a consequence, many antifungal drugs cause sideeffects. Some of these side-effects can be lifethreatening if the drugs are not used properly
Antiparasites
• Infections with parasitic helminthes and protozoa are
important causes of morbidity and mortality worldwide.
• No vaccines for antiparasitic infections
• In contrast to viruses, bacteria, and protozoa, most
helminthes do not directly replicate in the human body but
reproduce sexually, giving rise to eggs or larvae that pass out
of the body.
• These drugs often affect some of the more complex systems
of cellular physiology, such as microtubule formation or
neuromuscular function.
• The emergence of drug resistance in helminthes has been
much more gradual and limited than in rapidly replicating
protozoa, such as the malarial parasite Plasmodium
falciparum.
Classification of Antiparasites
•
•
•
•
•
Antinematodes
Anticestodes
Antitrematodes
Antiamoebics
Antiprotozoals
Metradinazole
Natural Antimicrobials/Non
Pharmaceutical Antimicrobials
• Plants have been used as traditional healers to
prevent or cure infectious diseases.
• Study have been done on their antimicrobial
activity and some inhibit the growth of
pathogenic microorganisms.
Essential Oils
• The antimicrobial properties of essential oils of 21
plant were investigated against five food-borne
pathogens:
Campylobacter jejuni,Salmonella enteriditis,
Escherichia coli, Staphylococcus aureus and
Listeria monocytogenes.
• The oils of bay, cinnamon, clove and thyme were the most
inhibitory, each having a bacteriostatic concentration of
0.075% or less against all five pathogens.
• Some Examples are: Eucalyptus oil, Garlic oil, Oregano oil,
Lavender oil, Lemon oil, Mint oil etc.
Side Effects of Antimicrobials
• Toxicities, the inability of a drug to completely
distinguish host physiology from pathogen
physiology
• Allergies
• Normal flora disruptions
• Antimicrobial Resistance
Antimicrobial Nanotechnology
• It is a recent addition to the fight against disease
causing organisms, replacing heavy metals and toxins
and may some day be a viable alternative.
• Many heavy metal cations such as Hg2+, Cu2+, and
Pb2+ have antimicrobial activities, but are also very
toxic to other living organisms, thus making them
unsuitable for treating infectious diseases.
• Silver is commonly used as an antimicrobial in
alternative medicine for its infection-fighting
properties and it has a long and intriguing history as
an antibiotic in human health care.
Questions