beta-lactams

Question 1

Mechanism of action

Answer 1

block cell wall synthesis by inhibition of peptidoglycan cross-linking

Question 2

Penicillin

Answer 2

Penicillin G (IV and IM forms), penicillin V (oral)

For:
S pneumo, S. pyogenes, actinomyces
neisseria meningitidis, treponema pallidum, syphilis

bactericidal: gram-positive cocci, gram-positive rods, gram-negative cocci, spirochetes

Toxicity: hypersensitivity reactions, hemolytic anemia

Resistance: beta-lactamases

Question 3

Oxacillin, nafcillin, dicloxacillin

Answer 3

Narrower spectrum than penicillin

Penicillinase resistant

S. aureus (except MRSA)

Hypersensitivity reactions, interstitial nephritis

Question 4

Ampicillin, amoxicillin

Answer 4

wider spectrum than penicillin
combine with clavulanic acid to protect against B-lactamases

H influenzae, E coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci

Hypersensitivity reactions, ampicillin rash, pseudomembranous colitis

Question 5

Ticarcillin, piperacillin

Answer 5

Pseudomonas spp. and gram negative rods
Use with clavulanic acid

Hypersensitivity reactions

Question 6

Cephalosporins (1st generation)

Answer 6

cefazolin, cephalexin

gram-positive cocci, Proteus mirabilis, E coli, Klebsiella pneumoniae

Question 7

Cephalosporins (2nd generation)

Answer 7

Cefoxitin, cefaclor, cefuroxime

gram-positive cocci, H influenzae, Enterobacter aerogenes, Neisseria spp, Proteus mirabilis, E coli, Klebsiella pneumoniae, Serratia marcescens

Question 8

Cephalosporins (3rd generation)

Answer 8

Ceftriaxone, cefotaxime

serious gram-negative infections
Ceftriaxone: meningitis, gonorrhea
Ceftazidime: Pseudomonas

Question 9

Cephalosporins (4th generation)

Answer 9

Cefepime

increased activity against pseudomonas and gram-positive organisms

Question 10

Aztreonam

Answer 10

Synergistic with aminoglycosides
monobactam resistant to beta-lactamases
no cross-allergenicity with penicillins

gram-negative rods only

Question 11

Imipenem/cilastain, meopenem

Answer 11

gram-positive cocci, gram-negative rods, anaerobes

wide spectrum, but side effects: GI distress, skin rash, CNS toxicity, seizures at high plasma levels

Question 12

Vancomycin

Answer 12

inhibits cell wall peptidoglycan formation: D-ala-D binding

gram-positive only (MRSA, enterococci, C diff)

toxicity: red man syndrome, nephrotoxicity, ototoxicity, thrombophlebitis