USMLE Step 1 Antibiotics Exam Questions with
Answers
1. Penicillin mechanism correct answer: binds to penicillin binding proteins in
peptidoglycan (blocks transpeptidase crosslinking); activates autolytic enzymes
2. penicillin use correct answer: gram positives and syphilis
3. penicillin toxicity correct answer: hypersensitivity reactions, hemolytic anemia
4. penicillinase resistant penicillins correct answer: methicillin, nafcillin, dicloxacillin
5. penicillinase resistant penicillin use correct answer: Staph aureus
6. penicillin resistant penicillin toxicity correct answer: hypersensitivity; methicillin correct
answer: interstitial nephritis
7. aminopenicillins correct answer: ampicillin, amoxacillin
8. aminopenicillin mechanism correct answer: same as penicillin but wider spectrum
9. aminopenicillin use correct answer: select gram positive and negative bacteria--H flu, E coli,
Listeria, Proteus, Salmonella,
enterococci
10. aminopenicillin toxicity correct answer: hypersensitivity, ampicillin rash,
pseudomembranous colitis
11. antipseudomonal drugs correct answer: ticarcillin, piperacillin, carbenicillin
12. antipseudomonal mechanism correct answer: same as penicillin; wider
spectrum
13. antipseudomonal use correct answer: Pseudomonas and gram negative rods
14. antipsuedomonal toxicity correct answer: hypersensitivity reaction
15. beta lactamase inhibitor mechanism correct answer: inhibit beta lactamase
(protects penicillins from destruc-
tion)
16. beta lacatamase drugs correct answer: clavulanic acid, sulbactam, tazobactam
17. bacteriostatic antibiotics correct answer: erythromycin, clindamycin, sulfamethoxazole,
trimethoprim, tetracycline,
chloramphenicol
18. bactericidal antibiotics correct answer: vancomycin, fluoroquinolones, penicillin,
aminoglycosides, cephalosporins, metronidazole
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,19. 1st generation cephalosporins correct answer: cefazolin, cephalexin
20. 1st generation cephalosporin coverage correct answer: gram positive cocci,
Proteus, E coli, Klebsiella
21. cephalosporin mechanism correct answer: beta lactams; inhibit cell wall synthesis but
less susceptible to penicilli-
nases
22. 2nd generation cephalosporins correct answer: cefoxitin, cefaclor, cefuroxime
23. 2nd generation cephalosporin coverage correct answer: same as 1st plus H flu,
enterobacter, Neisseria, Srratia
24. 3rd generation cephalosporins correct answer: ceftriaxone, ceftazidime,
cefotaxime
25. 3rd generation cephalosporin coverage correct answer: serious gram negative
infections; ceftriaxone correct answer: Neis-
seria, ceftazidime correct answer: pseudomonas
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, 26. 4th generation cephalosporins correct answer: cefepime
27. cephalosporin toxicity correct answer: hypersensitivity, vitamin K deficiency, cross-
hypersensitivity with penicillins, in-
crease nephrotoxicity of aminoglycosides, reaction with alcohol
28. aztreonam mechanism correct answer: beta lactamase resistant monobactam; binds
penicillin binding protein
29. aztreonam use correct answer: gram negative rods only
30. aztreonam toxicity correct answer: occasional GI upset
31. imipenem/cilastin mechanism correct answer: beta-lactamase resistant carbapenem;
cilastin is a renal dihy-
dropeptidase 1 (to decrease renal inactivation)
32. imipenem use correct answer: broad spectrum; gram +
cocci, gram - rods and anaerobes (use limited to life-threatening or
refractory infections because of side ettects)
33. imipenem toxicity correct answer: GI distress, skin rash, CNS toxicity (seizures) at high
plasma levels
34. vancomycin mechanism correct answer: inhibits cell wall mucopeptide formation by
binding D ala D ala portion of cell
wall precursors
35. vancomycin use correct answer: gram + only; use reserved for resistant infections--Staph
aureus, enterococci, C ditt
36. vancomycin toxicity correct answer: nephrotoxicity, ototoxicity, thrombophlebitis, red man
syndrome, but well-tolerated
in general
37. resistance to vancomycin correct answer: amino acid change from D-ala D-ala to
D-ala D-lac
38. 30s ribosomal inhibitors correct answer: tetracyclins, aminoglycosides
39. 50s ribosomal inhibitors correct answer: clindamycin, chloramphenicol, erythromycin,
linezolid, lincomycin
40. aminoglycoside drugs correct answer: gentamicin, neomycin, amikacin, tobramycin,
streptomycin
41. aminoglycoside mechanism correct answer: inhibit formation of the initiation complex
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Answers
1. Penicillin mechanism correct answer: binds to penicillin binding proteins in
peptidoglycan (blocks transpeptidase crosslinking); activates autolytic enzymes
2. penicillin use correct answer: gram positives and syphilis
3. penicillin toxicity correct answer: hypersensitivity reactions, hemolytic anemia
4. penicillinase resistant penicillins correct answer: methicillin, nafcillin, dicloxacillin
5. penicillinase resistant penicillin use correct answer: Staph aureus
6. penicillin resistant penicillin toxicity correct answer: hypersensitivity; methicillin correct
answer: interstitial nephritis
7. aminopenicillins correct answer: ampicillin, amoxacillin
8. aminopenicillin mechanism correct answer: same as penicillin but wider spectrum
9. aminopenicillin use correct answer: select gram positive and negative bacteria--H flu, E coli,
Listeria, Proteus, Salmonella,
enterococci
10. aminopenicillin toxicity correct answer: hypersensitivity, ampicillin rash,
pseudomembranous colitis
11. antipseudomonal drugs correct answer: ticarcillin, piperacillin, carbenicillin
12. antipseudomonal mechanism correct answer: same as penicillin; wider
spectrum
13. antipseudomonal use correct answer: Pseudomonas and gram negative rods
14. antipsuedomonal toxicity correct answer: hypersensitivity reaction
15. beta lactamase inhibitor mechanism correct answer: inhibit beta lactamase
(protects penicillins from destruc-
tion)
16. beta lacatamase drugs correct answer: clavulanic acid, sulbactam, tazobactam
17. bacteriostatic antibiotics correct answer: erythromycin, clindamycin, sulfamethoxazole,
trimethoprim, tetracycline,
chloramphenicol
18. bactericidal antibiotics correct answer: vancomycin, fluoroquinolones, penicillin,
aminoglycosides, cephalosporins, metronidazole
1/
17
,19. 1st generation cephalosporins correct answer: cefazolin, cephalexin
20. 1st generation cephalosporin coverage correct answer: gram positive cocci,
Proteus, E coli, Klebsiella
21. cephalosporin mechanism correct answer: beta lactams; inhibit cell wall synthesis but
less susceptible to penicilli-
nases
22. 2nd generation cephalosporins correct answer: cefoxitin, cefaclor, cefuroxime
23. 2nd generation cephalosporin coverage correct answer: same as 1st plus H flu,
enterobacter, Neisseria, Srratia
24. 3rd generation cephalosporins correct answer: ceftriaxone, ceftazidime,
cefotaxime
25. 3rd generation cephalosporin coverage correct answer: serious gram negative
infections; ceftriaxone correct answer: Neis-
seria, ceftazidime correct answer: pseudomonas
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, 26. 4th generation cephalosporins correct answer: cefepime
27. cephalosporin toxicity correct answer: hypersensitivity, vitamin K deficiency, cross-
hypersensitivity with penicillins, in-
crease nephrotoxicity of aminoglycosides, reaction with alcohol
28. aztreonam mechanism correct answer: beta lactamase resistant monobactam; binds
penicillin binding protein
29. aztreonam use correct answer: gram negative rods only
30. aztreonam toxicity correct answer: occasional GI upset
31. imipenem/cilastin mechanism correct answer: beta-lactamase resistant carbapenem;
cilastin is a renal dihy-
dropeptidase 1 (to decrease renal inactivation)
32. imipenem use correct answer: broad spectrum; gram +
cocci, gram - rods and anaerobes (use limited to life-threatening or
refractory infections because of side ettects)
33. imipenem toxicity correct answer: GI distress, skin rash, CNS toxicity (seizures) at high
plasma levels
34. vancomycin mechanism correct answer: inhibits cell wall mucopeptide formation by
binding D ala D ala portion of cell
wall precursors
35. vancomycin use correct answer: gram + only; use reserved for resistant infections--Staph
aureus, enterococci, C ditt
36. vancomycin toxicity correct answer: nephrotoxicity, ototoxicity, thrombophlebitis, red man
syndrome, but well-tolerated
in general
37. resistance to vancomycin correct answer: amino acid change from D-ala D-ala to
D-ala D-lac
38. 30s ribosomal inhibitors correct answer: tetracyclins, aminoglycosides
39. 50s ribosomal inhibitors correct answer: clindamycin, chloramphenicol, erythromycin,
linezolid, lincomycin
40. aminoglycoside drugs correct answer: gentamicin, neomycin, amikacin, tobramycin,
streptomycin
41. aminoglycoside mechanism correct answer: inhibit formation of the initiation complex
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