Occurrence of ESBL and AmpC Beta-Lactamase Producers Among Klebsiella pneumoniae Clinical Isolates – A Study from Chennai, Tamil Nadu, India

Introduction: The emergence of Extended Spectrum Beta-Lactamases (ESBLs), AmpC β-lactamases and their co-existence among the members of Enterobacteriaceae has been found to be alarmingly high and poses newer diagnostic and treatment challenges.  Materials and Methods: In this study, we investigated both ESBL and AmpC β-lactamases in clinical isolates of Klebsiella pneumoniae (64). The detection of ESBL and AmpC β-lactamases was performed based on screening and confirmatory tests. The isolates that screened positives were phenotypically confirmed by the double disc synergy test and the Cefoxitin-Cloxacillin Double disk synergy test. Conventional PCR was performed to screen for the presence of ESBL-encoding gene blaTEM and the AmpC- encoding gene blaMOX.  Result: The most common method used was DDST, which detected 50% of ESBL producers, followed closely by ESBL screening at 42.19%. Cefoxitin screening and the Cefoxitin-Cloxacillin Double Disk Synergy Test each accounted for 12.5% of the cases. ESBL gene was detected in 29 (46.7%) isolates. None of the isolates showed positive for blaMOX genes.  Conclusion: The Cefoxitin resistance was found to be a discriminative parameter in detecting the AmpC-producing strains. The high positive rate of ESBLs and AmpC beta-lactamases production in isolates calls for the need for strong intervention to minimize further occurrence and spread of such resistance.