Cephalosporins

Question 1

Mechanism of action

Answer 1

• Time dependent, bactericidal
• Post-antibiotic effect
• PBP - carbopeptidase and transpeptidate inhibition

Question 2

Resistance

Answer 2

1. E. coli, pseudomonas, staphyloccocus - B-lactamase

2. PBP mutation: MRSA, MESAP

Question 3

1st Generation

Answer 3

dermatitis, UTI (from staphylococcus, NOT E.coli).

• Pronounced activity against Gram-positive
• Gram-negative: NOT against lactamase producers
• Oral:
  1. Cephalexin - dermatitis, mastitis, UTI (not E.coli)
  2. Cefadroxil
• Parenteral: mastitis (G+), metritis
  1. Cephazoline- 3omin pre-surgery to avoid bacterial infection
  2. Cefacetril
  3. Cephapirin
  4. Cephalotin

Question 4

2nd Generation

Answer 4

• Less pronounced activity against Gram-positive
• Gram-negative: active against several lactamase producers! ( E. coli, Salmonella spp., Klebsiella spp)
• Oral:
  1. Cefuroxime axetil
  2. Cefaclor

*Parenteral:
Cefuroxime- rare, Respiratory infection , otitis

Question 5

3rd Generation

Answer 5

*Weak activity against Gram-positive
*Gram-negatives: active against most lactamase producers!
+ Pseudomonas aeruginosa! + fusobacteria
*(Oral: Cefixime - UTI,)
*Parenteral:
1. CEFOPERAZONE - UTI by E.coli, pseudomonas
2. Ceftiofur - Bo,Su. IM -Na short acting, -hydrochloride- long lasting,once, crystalline free acid form: very long,3 days.
3.Cefovecin
4.CEFTAZIDIME
5.ceftriaxone - meningitis , bile excretion
6.Cefotaxime - meningitis

Question 6

4th Generation

Answer 6

*good against GI problem, UTI, respiration, large animals

*Parenteral:
Cefquinome

Question 7

Distribution

Answer 7

down the generation the more lipophilic it is. 3rd gen crosses BBB and good to treat meningitis

Question 8

Metabolism

Answer 8

liver ,kidney.

*cefoperazone and ceftriaxone are safe for kidney patients

Question 9

Side effcet

Answer 9

Allergy, Dysbacteriosis (Eq), thrombocytopenia, tissue irritation (except Cefovecin), mild nephrotoxicity when bound to aminoglycosides (NEVER combine)