Genomic portrayal of emerging carbapenem-resistant El Tor variant Vibrio cholerae O1.

Abstract

The escalating prevalence of carbapenem-resistant (CR) enteric pathogens elicits significant challenges to public health management and effective antimicrobial therapy. While carbapenem resistance is rare in Vibrio cholerae O1 (VC), the recent emergence of CR strains reveals a concerning shift in their antimicrobial resistance (AMR) landscape. This study aims to characterize the resistance mechanisms in newly identified El Tor CRVC isolated from cholera patients in Gujarat, India during 2019. Fifty VC isolates were screened for major virulence-associated genes along with the determination of their antibiotic resistance profiles using Kirby-Bauer disk diffusion and MIC assays. Whole-genome sequencing (WGS) was employed to investigate the underlying mechanisms of CR. All the isolates exhibited hypervirulent Haitian alleles of major virulence genes and AMR profiles of typical multidrug resistance (MDR). Strikingly, 12% (6/50) of them were resistant to carbapenems and other antibiotics. Molecular analysis revealed that these CR isolates were clonally related and harbored a 142 kbp IncA/C type conjugative mega-plasmid with several AMR encoding genes, including bla_NDM-1, that can be easily transferred to other bacterial species and confer donor AMR patterns. The plasmid's competence for horizontal gene transfer presents a significant risk of dissemination to other enteric pathogens and thereby may complicate the treatment. This finding emphasizes the urgent need for enhanced genomic surveillance and robust antimicrobial stewardship programs aimed at curbing the spread of CRVC strains and mitigating their impact on cholera treatment and containment strategies.