Patient Case: AmpC
A 38 year old 
presents with suspected pyelonephritis and is started on empiric ceftriaxone. Her
cultures grow Enterobacter cloacae with pending susceptibilities. What the best treatment?
A) Ceftriaxone
B) Cefepime
C) Ceftazidime/Avibactam
How did others respond?
Reveal the answer
Best Answer
Cefepime
AmpC beta-lactamase enzymes will hydrolyze most penicillins and many cephalosporins. These enzymes are often produced in Enterobacter cloacae, Klebsiella aerogenes and Citrobacter freundii as well as some other Gram negatives :microbe: 2022 IDSA Guidance on AmpC producers suggests treatment with cefepime when MICExplanation: Ceftriaxone may appear to be susceptible based on cultures but there is a high risk of inducible resistance when the bacteria is exposed to ceftriaxone and risk of treatment failure Ceftazidime/avibactam would be active but should be saved for treatment of carbapenem-resistant isolates. Even in the setting of possible multi-drug resistant organisms it’s still best to avoid unnecessarily broad antibiotics