How should Enterobacter spp. and other AmpC producers be screened for ESBLs ?
The simplest way is to screen with cefepime and cefepime / clavulanic acid. There is an Etest strip for this combination. Cefepime is a very weak substrate for AmpC enzymes, but is a substrate for ESBLs. In the presence of clavulanate, ESBL-mediated cefepime resistance will be reduced, despite any induction of AmpC (see also the guidelines listed above).
