Multiplex pcr to detect pampc β-lactamases among enterobacteriaceae at a tertiary care laboratory in Mumbai, India

Drug-resistance due to AmpC β-lactamases represents a growing problem worldwide. In this study, a previously collected sample of 108 cefoxitin-resistant clinical isolates was assessed for AmpC b-lactamase production through routine phenotypic testing and double-disc cefoxitin/cloxcallin (DD-CC), cefoxitin/phenylboronic acid (CDT-PBA) and AmpC disc tests. The same isolates were characterized by a novel multiplex polymerase chain reaction molecular assay to detect the presence of bla _ACT , bla _DHA , bla _CIT , bla _FOX , bla _MIR and bla _MOX . By phenotypic analysis, 56%, 55% and 48 % were detected as being AmpC β-lactamase producers by the CDT-PBA, DD-CC and AmpC disc tests, respectively. By molecular analysis, 57 % were determined to be AmpC β-lactamase producers, including 34 % bla _FOX , 8 % bla _CIT and 1.6 % bla _DHA as mono-AmpC producers. The production of multiple AmpC molecular types was common, including 30 % with both bla _CIT+FOX and 1.6 % each of bla _CIT+DHA , bla _ACT+MIR , bla _ACT+FOX , bla _ACT+DHA and bla _MIR+FOX . Molecular characterization of AmpC would help detect the prevalence of AmpC β-lactamase producers, facilitate proper patient management and implement infection control practices.