USMLE Step 1 – 686 Pharmacology & Infectious
Disease Q&A – Kaplan Med Style (2025).
Study
Penicillin mechanism
binds to penicillin binding proteins in peptidoglycan (blocks transpeptidase crosslinking); activates
autolytic enzymes
penicillin use
gram positives and syphilis
penicillin toxicity
hypersensitivity reactions, hemolytic anemia
penicillinase resistant penicillins
methicillin, nafcillin, dicloxacillin
penicillinase resistant penicillin use
Staph aureus
penicillin resistant penicillin toxicity
hypersensitivity; methicillin: interstitial nephritis
aminopenicillins
ampicillin, amoxacillin
aminopenicillin mechanism
same as penicillin but wider spectrum
aminopenicillin use
select gram positive and negative bacteria--H flu, E coli, Listeria, Proteus, Salmonella, enterococci
aminopenicillin toxicity
hypersensitivity, ampicillin rash, pseudomembranous colitis
antipseudomonal drugs
ticarcillin, piperacillin, carbenicillin
, antipseudomonal mechanism
same as penicillin; wider spectrum
antipseudomonal use
Pseudomonas and gram negative rods
antipsuedomonal toxicity
hypersensitivity reaction
beta lactamase inhibitor mechanism
inhibit beta lactamase (protects penicillins from destruction)
beta lacatamase drugs
clavulanic acid, sulbactam, tazobactam
bacteriostatic antibiotics
erythromycin, clindamycin, sulfamethoxazole, trimethoprim, tetracycline, chloramphenicol
bactericidal antibiotics
vancomycin, fluoroquinolones, penicillin, aminoglycosides, cephalosporins, metronidazole
1st generation cephalosporins
cefazolin, cephalexin
1st generation cephalosporin coverage
gram positive cocci, Proteus, E coli, Klebsiella
cephalosporin mechanism
beta lactams; inhibit cell wall synthesis but less susceptible to penicillinases
2nd generation cephalosporins
cefoxitin, cefaclor, cefuroxime
2nd generation cephalosporin coverage
same as 1st plus H flu, enterobacter, Neisseria, Srratia
3rd generation cephalosporins
ceftriaxone, ceftazidime, cefotaxime
3rd generation cephalosporin coverage
serious gram negative infections; ceftriaxone: Neisseria, ceftazidime: pseudomonas
4th generation cephalosporins
Disease Q&A – Kaplan Med Style (2025).
Study
Penicillin mechanism
binds to penicillin binding proteins in peptidoglycan (blocks transpeptidase crosslinking); activates
autolytic enzymes
penicillin use
gram positives and syphilis
penicillin toxicity
hypersensitivity reactions, hemolytic anemia
penicillinase resistant penicillins
methicillin, nafcillin, dicloxacillin
penicillinase resistant penicillin use
Staph aureus
penicillin resistant penicillin toxicity
hypersensitivity; methicillin: interstitial nephritis
aminopenicillins
ampicillin, amoxacillin
aminopenicillin mechanism
same as penicillin but wider spectrum
aminopenicillin use
select gram positive and negative bacteria--H flu, E coli, Listeria, Proteus, Salmonella, enterococci
aminopenicillin toxicity
hypersensitivity, ampicillin rash, pseudomembranous colitis
antipseudomonal drugs
ticarcillin, piperacillin, carbenicillin
, antipseudomonal mechanism
same as penicillin; wider spectrum
antipseudomonal use
Pseudomonas and gram negative rods
antipsuedomonal toxicity
hypersensitivity reaction
beta lactamase inhibitor mechanism
inhibit beta lactamase (protects penicillins from destruction)
beta lacatamase drugs
clavulanic acid, sulbactam, tazobactam
bacteriostatic antibiotics
erythromycin, clindamycin, sulfamethoxazole, trimethoprim, tetracycline, chloramphenicol
bactericidal antibiotics
vancomycin, fluoroquinolones, penicillin, aminoglycosides, cephalosporins, metronidazole
1st generation cephalosporins
cefazolin, cephalexin
1st generation cephalosporin coverage
gram positive cocci, Proteus, E coli, Klebsiella
cephalosporin mechanism
beta lactams; inhibit cell wall synthesis but less susceptible to penicillinases
2nd generation cephalosporins
cefoxitin, cefaclor, cefuroxime
2nd generation cephalosporin coverage
same as 1st plus H flu, enterobacter, Neisseria, Srratia
3rd generation cephalosporins
ceftriaxone, ceftazidime, cefotaxime
3rd generation cephalosporin coverage
serious gram negative infections; ceftriaxone: Neisseria, ceftazidime: pseudomonas
4th generation cephalosporins
