The FOX gene family encodes plasmid AmpC enzymes that hydrolyze third-generation cephalosporins. FOX-type AmpCs confer extended-spectrum cephalosporin resistance, often in species lacking chromosomal AmpC. Its inclusion ensures detection of this additional AmpC-mediated resistance mechanism that can occur in Enterobacteriaceae (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
