Citrobacter koseri
General Susceptibility

General Susceptibility

  • Cefepime
  • Piperacillin-tazobactam (use caution in difficult-to-treat infections)
  • Meropenem
  • This organism may express an inducible beta-lactamase (AmpC) which can cause failure of penicillins, beta-lactam/beta-lactamase inhibitors, 1st-3rd generation cephalosporins, aztreonam, and ertapenem, despite in vitro susceptibility

Intrinsic resistance:

  • Ampicillin
  • Amoxicillin/clavulanate
  • Ampicillin/sulbactam
  • 1st & 2nd gen cephs (Cefazolin, Cephalothin, Cefuroxime)
  • Cephamycins (Cefoxitin, Cefotetan)