Topic: AntimicrobialsPresented by: Adeela Hussain

12-10403BIOT: 412

Antimicrobial Therapy

• Antimicrobials???

• Use of these Antimicrobials to treat diseases

Antimicrobial TherapyCategorized as:

Empiric Definitive Prophylactic Infecting

organism not yet identified( i.e. specific organism)

Broad Spectrum

Infecting organism identified

Specific Therapy

Narrow Spectrum

Prevent previous infection or its recurrence after infection

Preventive

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???

•Antimicrobials•Classification according to their mode of action

Know the drug•Culture results----Susceptible, Intermediate, or

Resistant•Minimum inhibitory concentration•Specificity•Drug’s Activity

Know the microbiology

•Dose and route of administration•Allergy•Age•Pregnancy•Genetic and metabolic abnormalities•Renal and hepatic function

Know the patient

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 byAltered 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 side-effects. Some of these side-effects can be life-threatening 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