Question | Answer |
block nucleotide synthesis | sulfonamides, trimethoprim |
block DNA topoisomerases | quinolones |
block mRNA synthesis | rifampin |
block protein synthesis at 50S ribosomal subunit | chloramphenicol, erythromycin/macrolides, lincomycin, clindamycin, streptogramins (quinupristin, dalfopristin), linezolid |
block protein synthesis at 30S ribosomal subunit | aminoglycosides, tetracyclines |
bacteriacidal antibiotics (6) | penicilin, cephalosporins, vancomycin, aminoglycosides, fluoroquinolones, metronidazole |
penicillin mechanism | bind PBPs, block transpeptidase cross-linking of cell wall; activate autolytic enzymes |
penicillin toxicity | hypersensitivity reactions, hemolytic anemia |
mechanism of methicillin, nafcillin, dicloxacillin | bind PBPs, block transpeptidase cross-linking of cell wall - penicillinase resistant because of bulkier R group |
methicillin toxicity | interstitial nephritis |
ampicillin, amoxicillin toxicity | hypersensitvity, ampicillin rash (esp. in pts. w/ mono), pseudomembranous colitis |
ticarcillin, carbenicillin, piperacillin usage | pseudomonas (Takes Care of Pseudomonas) |
mechanism of cephalosporins | beta-lactam drugs that inhibit cell wall synthesis - less susceptible to penicillinases |
antibiotic for penicillin-allergic patients and patients w/ renal toxicity who can't tolerate aminoglycosides | aztreonam (synergistic w/ aminoglycosides) |
drug of choice for enterobacter | imipenem/cilastin |
antibiotic that can cause seizures at high plasma levels | imipenem/cilastin |
mechanism of vancomycin | inhibits cell wall mucopeptide formation by binding D-ala D-ala portion of cell wall precursors |
mechanism of resistance to vancomycin | amino acid change of D-ala D-ala to D-ala D-lac |
vancomycin toxicity | well tolerated in general - does NOT have many problems: nephrotoxicity, ototoxicity, thrombophlebitis |
aminoglycosides | streptomycin, gentamicin, tobramycin, amikacin - bacteriacidal |
mechanism of action of aminoglycosides | inhibit 30S subunit - inhibit formation of initiation complex and cause misreading of mRNA |
are aminoglycosides effective agains anaerobes? | no! require O2 or uptake |
aminoglycosides cause nephrotoxicity especially when used in combination with _________ | cephalosporins |
aminoglycosides cause ototoxicity especially when used with_________ | loop diuretics |
are aminoglycosides safe to use in pregnancy? | no! teratogenic |
which tetracycline can be used in patients with renal failure? | doxycycline because it is fecally eliminated |
can you take tetracyclines with milk? | no! nor atacids or iron-containing preparations because divalent cations inhibit its absorption in the gut |
tetracycline toxicity | discoloration of teeth and inhibition of bone growth in children, photosensitivity |
mechanism of action of macrolides | inhibit protein synthesis by blocking translocation - bind to 23S rRNA of the 50S subunit |
name 3 macrolides | erythromycin, azithromycin, clarithromycin |
when can sulfonamides cause hemolysis? | G6PD deficiency |
most common cause of noncompliance with macrolides | GI discomfort |
macrolides increase the serum concentration of what drugs? | theophyllines, oral anticoagulants |
acute cholestatic hepatitis & eosinophilia are toxicities of which class of antibiotics? | macrolides |
clinical use of chloramphenicol | meningitis - H. flu, neisseria, strep pneumo |
why does chloramphenicol cause gray baby syndrome? | because infants lack liver UDP-glucoronyl transferase |
is the aplastic anemia seen with chloramphenicol dose dependent? | no! the anemia is, however |
mechanism of action of chloramphenicol | inhibits 50S peptidyltransferase |
what is the clinical use of clindamycin? | treatment of anaerobic infections - B. frag, C. perfringfens |
clindamycin toxicity | pseudomembranous colitis - destroys normal GI flora |
mechanism of action of sulfonamides (sulfamethoxazole, sulfisoxazole, triple sulfas, etc.) | PABA antimetabolites inhibit dihydropteroate synthase |
what side effect can sulfonamides cause in infants? | kernicterus |
mechanism of action of trimethoprim | inhibits bacterial dihydrofolate reductase |
trimethoprim toxicity | megaloblastic anemia, leukopenia, granulocytopenia (may alleviate with supplemental folinic acid) |
mechanism of action of fluoroquinolones | inhibit DNA gyrase (topoisomerase II) |
what class of antibiotics can cause cartilage damage in kids? | fluoroquinolones |
what drug is associated with a disulfiram-like reaction with alcohol and a metallic taste | metronidazole |
what can prevent the neurotoxicity associated with INH? | pyridoxine (vitamin B6) |
INH toxicity | hemolysis if G6PD deficient, neurotoxicity, hepatotoxicity, SLE-like syndrome |
mechanism of action of rifampin | inhibits DNA-dependent RNA polymerase |
what drug delays resistance to dapsone when used for leprosy? | rifampin |
resistance mechanism for penicillins/cephalosporins | beta-lactamase cleavage of beta lactam ring |
resistance mechanism for aminoglycosides | modification via acetylation, adenylation, or phosphorylation |
resistance mechanism for chloramphenicol | modification via acetylation |
resistance mechanism for macrolides | methylation of rRNA near erythromycin's ribosome binding site |
resistance mechanism for tetracycline | decreased uptake or increased transport out of cell |
resistance mechanism for sulfonamides | altered enzyme (bacterial dihydropteroate synthetase), decreased uptake, or increased PABA synthesis |
mechanism of action of amphotericin B | binds ergosterol (unique to fungi); forms membrane pores that allow leakage of electrolytes and disrupt homeostasis |
drug of choice for systemic mycoses | amphotericin B |
amphotericin B toxicity | fever/chills, hypotension, nephrotoxicity, arrhythmias, hypochromic normocytic anemia |
do ketoconazole and ampho B act synergistically? | no - they antagonize each other's actions, so should never be used together |