Molecular screening of extended-spectrum β-lactamase and carbapenemase resistance genes in hospital wastewater from Eastern Odisha: Predominance of extended-spectrum β-lactamase determinants and absence of blaNDM and blaKPC

Abstract

The objective of the study is to determine the prevalence of antibiotic-resistant bacteria and characterize major ESBL and carbapenemase resistance genes in HWW from Bhubaneswar, Odisha, India. Wastewater samples were collected quarterly from six tertiary-care hospitals between May 2022 and February 2023. A total of 164 bacterial isolates were recovered and identified by conventional microbiological methods. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disk diffusion method. Thirty-eight multidrug-resistant isolates representing different bacterial species, hospital sites, and resistance profiles were selected for molecular analysis. Genomic DNA was extracted by the salting-out method, and polymerase chain reaction was used to detect blaTEM, blaCTX-M, blaSHV, blaOXA, blaKPC , and blaNDM genes. Categorical data were summarized using frequencies and percentages. Among the 164 isolates, Klebsiella pneumoniae (62%) was the predominant species, followed by Escherichia coli (25%), Pseudomonas aeruginosa (10%), and Enterococcus spp. (3%). High resistance rates were observed against cefuroxime (100%), piperacillin/tazobactam (99%), ofloxacin (99%), norfloxacin (98%), and nitrofurantoin (97%). Molecular analysis showed that blaTEM (34%) was the most prevalent gene, followed by blaCTX-M (26%), blaOXA (18%), and blaSHV (13%), whereas blaKPC and blaNDM were not detected. HWW in eastern Odisha harbors multidrug-resistant bacteria and ESBL-associated resistance genes, emphasizing the need for continuous environmental surveillance and improved wastewater management.