Characterizing carbapenemase production in Enterobacterales through combined disk test and genetic profiling

Objectives: Carbapenem-resistant Enterobacterales (CRE) are a major organism among the critical group of drug-resistant bacteria and are associated with high morbidity and mortality. With limited treatment options, the detection and characterization of carbapenemase are important for appropriate management. This study aims to characterize carbapenemase produced by Enterobacterales using a combined disk test and molecular profiling. Materials and Methods: All CRE isolated from various clinical samples were included in the study. Carbapenemase production was characterized by observing synergy on combining meropenem disk with beta-lactamase inhibitors such as phenylboronic acid, ethylenediaminetetraacetic acid, and cloxacillin, following which genetic profiling was done using multiplex polymerase chain reaction. Statistical analysis: Statistical analyses were done using the Statistical Package for the Social Sciences Statistics and Microsoft Excel. The data were presented in tables, charts, and graphs to elucidate the findings comprehensively. Results: Out of 445 Enterobacterales isolated, 104 (23.4%) were carbapenem-resistant. The most common CRE isolated was Klebsiella pneumoniae (62 out of 104), followed by Escherichia coli (40 out of 104), and two out of 104 CRE isolates were Enterobacter species. Coproduction of NDM and OXA-48-like enzymes (39.4%) was the most common mechanism, followed by NDM alone (19.2%) and OXA-48 alone (16.3%). NDM was the most common gene detected overall, with 72 out of 104 CRE (69.2%) isolates showing its presence, followed by OXA-48 present in 63 of 104 (60.6%) isolates. Conclusions: Metallo-beta-lactamases (NDM) were the predominant type of carbapenemase gene detected among the Enterobacterales isolates, with the coproduction of NDM and OXA-48 enzymes being the most common mechanism of resistance.