Ch. 20 Antimicrobial Drugs Flashcards
Paul Ehrlich
speculated about some “magic bullet” to destroy pathogens but not the host. This idea provided the basis for both selective toxicity and chemotherapy (term he coined)
which is the most ideal spectrum of activity (narrow vs broad)
narrow; less collateral damage
selective toxicity
drug affects pathogens, not host cells
superinfection
occurs with normal microbiota when they lose competitors and grow out of control. Kill normal microbiota that keep certain bacteria under control;
Five main actions of antimicrobial drugs
1) inhibition of cell wall synthesis
2) inhibition of protein synthesis
3) inhibition of nucleic acid replication and transcription
4) injury to plasma membrane
5) inhibition of essential metabolite synthesis
drugs that inhibit cell wall synthesis
penicillins, cephalosporins, bacitracin, vancomycin
inhibition of cell wall synthesis: penicillin
Inhibit formation of cross-bridges as you make peptidoglycan (more effective against gram positive)
drugs that inhibit protein synthesis
chloramphenicol, erythromycin, tetracyclines, streptomycin
inhibition of protein synthesis
Selective toxicity key (so it does not target our protein synthesis)
E.g. attacking 70s ribosome (prokaryotic) instead of 80s ribosome (ours)
Not all in the same way; target different parts of ribosome etc
drugs that inhibit nucleic acid replication and transcription
quinolones, rifampin
why are there not as many drugs that inhibit nucleic acid replication and transcription?
Not many since they are not many differences between prokaryotes and eukaryotes.
drug that injures plasma membrane
polymyxin B
function of injury to plasma membrane
Degrade integrity
Some antifungal drugs do the same
drugs that inhibit essential metabolite synthesis
sulfanilamide, trimethoprim
function of drugs that inhibit essential metabolite synthesis
Competitive inhibition
Both of these interfere with folic acid synthesis (we can’t make it)
Often prescribed together d/t synergism
