AmpC β-lactamases hydrolyze cephamycins (e.g. cefoxitin) and many penicillins/cephalosporins. Plasmids have mobilized AmpC genes (like CMY-2) into E. coli, Klebsiella, etc., broadening resistance in strains that normally lack chromosomal AmpC. Detecting the ampC family on plasmids is therefore critical for identifying otherwise silent resistant organisms (Jacoby 2009, Rodríguez-Guerrero et al. 2022) .
Jacoby G. A. (2009). AmpC beta-lactamases. Clinical microbiology reviews, 22(1), 161–182. https://doi.org/10.1128/CMR.00036-08
Rodríguez-Guerrero, E., Callejas-Rodelas, J. C., Navarro-Marí, J. M., & Gutiérrez-Fernández, J. (2022). Systematic Review of Plasmid AmpC Type Resistances in Escherichia coli and Klebsiella pneumoniae and Preliminary Proposal of a Simplified Screening Method for ampC. Microorganisms, 10(3), 611. https://doi.org/10.3390/microorganisms10030611
