Metallo-β-lactamase mediated resistance and Class 1 integron in carbapenem-resistant Enterobacterales isolates from the clinical specimens of Nepal.

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) pose an escalating public health threat due to their limited therapeutic options and their potential for rapid dissemination in healthcare settings. Mobile genetic elements (MGEs), such as integrons, facilitate the acquisition and dissemination of antimicrobial resistance genes, contributing to multidrug resistance. This study aimed to detect metallo-β-lactamase (MBL) encoding genes, blaNDM-1, blaVIM, and blaIMP, as well as class 1 integron gene (intI1) among clinical CRE isolates in a tertiary care hospital in Nepal.

METHODS

A six-month observational cross-sectional study was conducted in a tertiary care hospital in Nepal. A total of 3,255 clinical specimens were processed to isolate Enterobacterales species and to assess their antibiotic susceptibility by Kirby-Bauer disc diffusion. Carbapenemase and MBL production were phenotypically confirmed by the modified carbapenem inactivation method (mCIM) in combination with the EDTA-modified carbapenem inactivation method (eCIM). MBL encoding genes blaNDM-1, blaVIM, and blaIMP and class 1 integron (intI1) were detected by polymerase chain reaction.

RESULTS

Among 464 Enterobacterales isolates, 58.6% were multidrug-resistant, and 13.6% were carbapenem-resistant. Phenotypic detection confirmed MBL production in 84.1% of CRE isolates. The blaNDM-1 and blaVIM genes were detected in 57.1% and 31.7% CRE isolates, respectively, while blaIMP was not detected in any of the isolates. Notably, the class 1 integron gene was present in 98.4% of CRE isolates, indicating a high potential for horizontal gene transfer.

CONCLUSIONS

The high prevalence of MBL genes and class 1 integrons among CRE isolates highlights a substantial risk of carbapenem resistance spreading in healthcare settings in Nepal. These findings emphasize the urgent need for prompt detection, enhanced infection control and antimicrobial stewardship to curb the spread of highly resistant Enterobacterales.