Lecture 15

• Inhibition of bacterial cell wall synthesis
• Alter permeability of bacterial cell membreane
• Anti-metabolite avtivity - sulfer drugs
• Inhibitioin of bacterial protein synthesis
• Inhibition of bacterial necleic acid synthesis

Paul Ehrlich

Fleming

• Selectively toxic to the microbe but nontoxic to host cells
• Microbicidal rather than microbistatic
• Relatively soluble; functions even when highly diluted in body fluids
• Remains potent long enough to act and is not broken down or excreted prematurly
• Doesnt lead to the development of antimicrobial resistance
• Complements or assist the activities of the hosts defenses
• Remains active in tissues and body fluids
• Readily delivered to the site of infection
• Reasonably priced
• Does not disrupt the hosts health by causing allergies or predisposing the host to other infections

Any chemical used in the treatment, relief, or prophlaxis of a disease

Use of a drug to prevent imminent infection of a person at risk

The use of chemotherapeutic drugs to control infection

All-inclusive term for any antimicrobial drug, regardless of its orgin

Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms

Drugs which are chemically modified in the laboratory after being isolated from natural sources

The use of chemical reactons of synthesize antimicrobial compounds in the labratory

Antimicrobials effective against a limited array of micobial types

Antimicrobials effective against a wide variety of microbial types

• Metabolic products of bacteria and fungi
• Reduce competition for nutrients and space

Bacteria that produce them - Streptomyces, Bacillus, Escherichia

Molds - Penicillium, Cephalosporium

• Bacteriocidal
• Penicillin and cephalosporins
• - Binds and blocks peptidases involved in crosslinking the peptidoglycan molecules

• Vancomycin
• - Hinders peptidoglycan elongation

• Cycloserine
• - Inhibits the formation of the basic peptidoglycan subunits

• Aminoglycosides
• -Streptomycin, tetracycline, chloramphenicol
• -Macrolides
• - Erythromycin, Z-Pak

• Bind to the 30s ribosomal subunits
• Causes misreading of mRNA

From Streptomyces spp.

Block attachment of tRNA

• Bind to the 50s ribosomal subunit
• Prevents peptide bond formation

• Tetracycline-
• Broad spectrum and low cost
• Commonly used to treat STD's

• Erythromycin-
• Broad spectrum
• Commonly used as prophylactic drug prior to surgery

• Chloramphenicol-
• Broad spectrum
• Treat typhoid fever, brain abcesses
• Has a side effect of - Aplastic anemia

• Rifamycin-
• Inhibits RNA synthesis, Antituberculosis

• Quinolones and fluoroquinolones-
• Ciprofloxacin, Inhibits DNA gyrase, Urinary tract infections

• Sulfonamides (sulfa drugs) and trimthoprim-
• Analogs, Completitive inhibition of enzymes, Prevents the metabolism of DNA, RNA and amino acid

Works because mammals get folic acid from the diet and bacteria must make their own

• Increasing types of drugs becoming avaliable
• Efective drugs - target viral replication cycle: Entry, Nucleic acid synthesis, Assembly and release
• Interferon - genetically engineered aniviral protien from a human gene

• Antifungal - Ketoconizole
• Antiprotozoan- metronidazole (treat giardia)
• Antimalarial - Quinine (treat malaria)
• Anthihelminthic - mebendazole (treat tapeworms, roundworms)

• Exposure to sub-optimal levels of antimicrobial
• Inappropriate use
• Exposure to microbes carrying resistance genes

• Prescription not taken correctly
• Antibiotics for viral infections
• Antibiotics sold without medical supervision
• Spread of resistant microbes in hospitals due to lack of hygiene
• Inadequate surveillance or defective susceptibility assays (giving drugs that are not effective)
• Poverty or war
• Use of antibiotics in food

Cause teeth dicoloration

• Identify infectious agent - Culture
• Perform sensitivity testing - Mueller Hinton agar
• Often the minimum inhibitory concetration (MIC) is determined

Kirby-Bauer Test

• Infections resistant to avaliale antibiotics
• Increased cost of treatment

• Speed development of new antibiotics - fast track FDA
• Track resistance data nationwide
• Restrict antimicrobial use
• Direct observed dosing (TB)
• Use more narrow spectrum antibiotics
• Use antimicrobial cocktails

Antimicrobial peptides - broad spectrum antibiotics from plants and animals

Antisense agents- complementary DNA or peptide nucleic acids that binds to a pathogens virulence genes and prevents transcription