USMLE Step 1 Antibiotics Exam Questions (198 Terms) with Complete Elaborations 2026-2027 (22pages)

USMLE Step 1 Antibiotics Penicillin mechanism - Answer: binds to penicillin binding proteins in peptidoglycan (blocks transpeptidase crosslinking); activates autolytic enzymes penicillin use - Answer: gram positives and syphilis penicillin toxicity - Answer: hypersensitivity reactions, hemolytic anemia penicillinase resistant penicillins - Answer: methicillin, nafcillin, dicloxacillin penicillinase resistant penicillin use - Answer: Staph aureus penicillin resistant penicillin toxicity - Answer: hypersensitivity; methicillin: interstitial nephritis aminopenicillins - Answer: ampicillin, amoxacillin aminopenicillin mechanism - Answer: same as penicillin but wider spectrum aminopenicillin use - Answer: select gram positive and negative bacteria--H flu, E coli, Listeria, Proteus, Salmonella, enterococci aminopenicillin toxicity - Answer: hypersensitivity, ampicillin rash, pseudomembranous colitis USMLE Step 1 Antibiotics antipseudomonal drugs - Answer: ticarcillin, piperacillin, carbenicillin antipseudomonal mechanism - Answer: same as penicillin; wider spectrum antipseudomonal use - Answer: Pseudomonas and gram negative rods antipsuedomonal toxicity - Answer: hypersensitivity reaction beta lactamase inhibitor mechanism - Answer: inhibit beta lactamase (protects penicillins from destruction) beta lacatamase drugs - Answer: clavulanic acid, sulbactam, tazobactam bacteriostatic antibiotics - Answer: erythromycin, clindamycin, sulfamethoxazole, trimethoprim, tetracycline, chloramphenicol bactericidal antibiotics - Answer: vancomycin, fluoroquinolones, penicillin, aminoglycosides, cephalosporins, metronidazole 1st generation cephalosporins - Answer: cefazolin, cephalexin 1st generation cephalosporin coverage - Answer: gram positive cocci, Proteus, E coli, Klebsiella USMLE Step 1 Antibiotics cephalosporin mechanism - Answer: beta lactams; inhibit cell wall synthesis but less susceptible to penicillinases 2nd generation cephalosporins - Answer: cefoxitin, cefaclor, cefuroxime 2nd generation cephalosporin coverage - Answer: same as 1st plus H flu, enterobacter, Neisseria, Srratia 3rd generation cephalosporins - Answer: ceftriaxone, ceftazidime, cefotaxime 3rd generation cephalosporin coverage - Answer: serious gram negative infections; ceftriaxone: Neisseria, ceftazidime: pseudomonas