Chapter 20 Antimicrobial Drugs

bacteriostatic

inhibits growth of bacteria but does not kill it

bactericidal

kills bacteria

beta-lactam

blocks transpeptidase (enzyme that builds the bacterial cell wall)

beta-lactamase

destroys beta-lactam, promotes bacterial life

penicillin (cell wall targeting)

beta-lactam, can cause GI upset and rash, effective against gram positive bacteria, not as effective against gram negative, ends in -illin

cephalosporins (cell wall targeting)

beta-lactams, effective against gram positive

carbapenems (cell wall targeting)

beta-lactams, effective against gram positive and multidrug resistant bacteria

glycopeptide drugs (cell wall targeting)

NOT beta-lactams, effective against gram positive bacteria ex.) vancomycin

quinolones (nucleic acid targeting)

target DNA replication enzymes, good against gram negative and positive

ansamycins (nucleic acid targeting)

rifampin (type of this drug), binds to RNA polymerase and inhibits transcription, combined to treat mycobacterium and legionnaire’s disease

acyclovir

first truly effective antiviral, used against herpesvirus, designed to look like guanine

AZT

reverse transcriptase inhibitors, human cells do not contain this, so it is effective

polyenes

destabilize fungal plasma membrane by binding to ergosterol (basically fungal cholesterol)

Azoles

inhibit formation of ergosterol which damages the membrane

echinocandins

inhibits the creation of beta glucan in cell wall

quinine

anti-malarial because it cannot metabolize hemoglobin, chloroquine was developed but is less effective

metronidazole

antibiotic and antiprotozoal; treats giardiasis, trichomoniasis, and amebiasis

‘superinfections’

caused by a resistant microbe, seen in hospitals

intrinsic resistance

bacteria is ‘born’ with resistance

acquired resistance

bacteria acquires it resistance as it grows

horizontal gene transfer

the sharing of DNA between two bacteria that exist simultaneously

Kirby Bauer test

drug infused paper is placed in the middle of a colony

zone of inhibition appears (larger the zone the more effective the drug)

can’t distinguish between bacteriostatic and bactericidal