chapter 12

to administer a drug to an infected person that destroys the infective agent without harming the hosts cell

selectively toxic to the microbe but nontoxic to host cells, microbicidal rather than microbistatic, remains potent long enough to act and is not broken down or excreted prematurely, is not subject to the development of antimicrobial resistance, complements or assists the activities of the hosts defenses, remains active even when diluted in body fluids and tissues, 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 treatment, relief, or prophylaxis of a disease

any antimicrobial drug, regardless of it’s origin

substances produced naturally by some microorganisms that inhibit or destroy other microorganisms

drugs that are chemically modified in the laboratory after being isolated from natural sources

antimicrobial compounds synthesized in the laboratory

antimicrobials effective against a limited number of bacteria; for example, a drug effective on gram positive bacteria only

effective against a large variety of microbial species; for example, a drug effective against both gram positive and gram negative bacteria. Can lead to a superinfection (examples: yeast infections caused by Candida albicans yeast or colitis caused by clostridium difficile)

use of a drug to prevent potential for infection in a person at risk

the use of chemotherapeutic drugs to control infection

produced by some bacteria and fungi

bacteria in genera streptomyces and bacillus, fungi in genera penicillium and cephalosporium, penicillin is the first antibiotic discovered

first to develop screening methods: tested wide variety of compounds to identify antimicrobials, found an arsenic compound that target syphilis

the first synthetic antimicrobial developed. it served as the starting point for development of a family of sulfa drugs. these types of drugs inhibit bacterial metabolic pathways

determined the structure of penicillin, which was fundamental to develop semi-synthetic penicillins

actinomyces, streptomyces, actinomycin, streptomycin, neomycin

slows the growth but does not kill the bacteria

kill the target bacteria

class of antibiotics that block the biosynthesis of peptidoglycan (bacteria more suspectible to osmotic lysis) Penicillin and it’s derivatives are all b-lactams

inhibition of cell wall synthesis (penicillins and cephalosporins), breakdown of the cell membrane structure or function (examples: polymyxins in bacteria affect mostly gram negative bacteria), interference with functions of DNA and RNA, inhibition of protein synthesis: ribosomes of bacteria are of different size (70s): (can target 30S or 50S subunits, inhibit peptide bond formation, or block attachment of tRNA, blocking essential metabolic pathways: (sulfa drugs)

drug competes with normal substrate for enzymes active site

it is toxic to fungal cells also capable of harming human cells

ergosterol because fungal sterol differs from animal cholesterol (example: imidazole drugs such as miconazole and ketoconazole), fungal membrane, fungal cell wall

block penetration into host cell, block replication, transcription, or translation of genetic material, prevent maturation of viral particles

drug inactivation, activation of drug pumps, change or mutation in drug binding site, use of alternate metabolic pathway