M134-4

Abdominal Abscess: Klebsiella pneumoniae (Ertapenem-Resistant)  – Shipped February 2014

HISTORY

The challenge was sent to category A laboratories. The sample was a simulated intra-abdominal abscess fluid obtained from a 66 year old male patient.

Laboratories were expected to isolate, identify, and report Klebsiella pneumoniae. Participants were asked to report susceptibility results to third generation cephalosporins, carbapenems, aminoglycosides, trimethoprim-sulfa-methoxazole (SXT), piperacillin-tazobactam, and ciprofloxacin.

MAIN EDUCATIONAL POINTS from M134-4

  1. If evidence of more than one morphotype exists, both should be identified so that susceptibilities on each can be performed. In such cases it may occur that one is quite susceptible and the other multi-resistant. Picking the susceptible one only could have significant consequences for treatment, outcome and spread of the organism in hospital.
  2. An isolate of Enterobacteriaceae may carry multiple beta-lactam resistance mechanisms, including ESBLs, AmpCs, and carbapenemases. It is sometimes difficult in the laboratory to determine if an isolate has an ESBL alone or is AmpC positive also, but ertapenem is a useful marker to determine altered effects on carbapenems.

Full critique (PDF)

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