Cephalosporins

Question 1

Mechanism of action of cephalosporins

Answer 1

Inhibit bacterial wall cell wall synthesis - bactericidal

Question 2

How are cephalosporins primarily excreted

Answer 2

Renally

Question 3

Penetration of the cerebrospinal fluid

Answer 3

Poor - unless meninges inflammed

Question 4

Which two cephalosporins are suitable for CNS infections (meningtitis)

Answer 4

Cefotaxime and ceftriaxone

Question 5

Percentage of cross-reactivity between penicillins and first + early second cephalosporins and third generation

Answer 5

First and early 2nd - 10%

Third - 2-8%

Question 6

Which cephalosporins should you AVOID in penicillin allergy

Answer 6

Cefaclor, cefadroxil, cefalexin, cefradine and ceftaroline fosamil

Question 7

What are the principle side effect of cephalosporins

Answer 7

Hypersensitivity
Antibiotic associated colitis
C diff (more likely with 3rd and 4th gen)
SCARs (severe cutaenous reactions)
GI upset (d, n, v, abdo discomfort)

Question 8

Cephalosporins pregnancy and BF

Answer 8

Fine in both

Question 9

Interactions

Answer 9

Warfarin - increases anticoag effect, increases bleeding

Increased risk of nephrotoxicity with NSAIDs, gentamicin and methotrexate