Antibiotics Flashcards
What are the 5 major categories of antibiotic mechanism?
Cell wall synthesis inhibitors, protein synthesis inhibitors, nucleic acid synthesis inhibitors, cell membrane disrupters, and antimycobacterials
What classes of drugs are cell wall synthesis inhibitors?
Beta-lactams and Glycopeptides (Vancomycin)
What are the subclasses of beta-lactam drugs?
Penicillins, cephalosporins, carbapenems, and monobactams
What are the different categories of penicillins and what is the prototypial example of each?
Natural penicillins (Penicillin G); Aminopenicillins (ampicillin); penicillinase-resistant penicillins (nafcillin); and ureidopenicillins (piperacillin-tazobactam)
What is the mechanism of action of beta-lactams?
They interfere with transpeptidases involved in cell wall synthesis
What is the mechanism of resistance to beta-lactams?
Beta-lactamases; Altered affinity of transpeptidase or penicillin-binding proteins, efflux pumps, or decreased membrane permeability to the drugs
How are the cephalosporins grouped? What is the prototype of each group?
1st Gen: Cefazolin; 2nd Gen: Cefoxitin; 3rd Gen: Ceftriaxone; Other Gen: Cefipime
What class of drug is imipenem?
A carbapenem beta-lactam
What class of drug is aztreonam?
Monobactam beta-lactam
What is the mechanism of resistance against vancomycin?
R-plasmid codes for VanH (converts pyruvate to D-Lac) and VanA (binds D-Ala to D-Lac). When incorporated into the bacterial cell wall, vancomycin cannot bind
What are the four major classes of antibiotic protein synthesis inhibitors? What are the prototypes of each class?
Aminoglycosides (Gentamycin), Macrolides (Azithromycin), Lincosamides (Clindamycin), and Tetracyclines (Minocycline)
What is the mechanism of action of gentamycin?
Binds to 30S subunit of ribosome, halting translation
What is the mechanism of resistance against gentamycin?
Enzymatic modification; decreased uptake, mutation in the ribosome
What is the mechanism of action of azithromycin and clindamycin?
Prevent translocation of polypeptide chain
What is the mechanism of resistance against azithromycin?
Efflux, ribosomal protection by methylation, esterase degradation of the drug, ribosomal mutations
What is the mechanism of action for minocycline? The mechanism of resistance against minocycline?
Minocycline inhibits translocation by blocking the A site; Decreased uptake, active efflux, production of protection protein, and enzymatic inactivation all contribute to resistance
What are the major categories of nucleic acid synthesis inhibiting antibiotics? What is the prototype of each?
Fluoroquinolones (Ciprofloxacin); Rifamycin (Rifampin); Nitroimidazoles (Metronidazole); and Sulfamides (trimethoprim-sulfamethoxazole)
What is the mechanism of Ciprofloxacin’s action? Resistance against it?
Ciprofloxacin targets DNA gyrase (G-) and topoisomerase IV (G+)
What is the mechanism of rifampin’s action? Resistance against it?
Rifampin inhibits DNA-dependent RNA polymerase; Altered target
What is the mechanism of metronidazole’s action?
The prodrug gets an electron from ferredoxin to make a reactive nitro radical ion which targets and damages DNA
What is the general mechanism of sulfonamides’ action? Resistance against it?
Sulfonamides are competitive inhibitors of dihydropteroate synthase (block folate synthesis); Altered affinity of enzymes for drug, decreased intake, active efflux, alternate pathway for folic acid synthesis
What are the major antimycobacterials?
Isoniazid, Ethambutol, and Pyrazinamide
