Work

Incidence of carbapenem non-susceptible Chromobacterium violaceum harboring blaOXA-232 from clinical-environmental interface

Year: 2025

Type: article

Abstract: Purpose Chromobacterium violaceum is an opportunistic environmental pathogen, which act as a potential source of antimicrobial resistance genes. Acquisition of such genes by non-susceptible organisms, aided by mobile genetic elements possess a serious clinical threat. With the rise and expansion of carbapenem resistance worldwide, the present study investigates two carbapenem non-susceptible Chromobacterium violaceum isolates through whole genome sequencing. Methods The study isolates were assessed for ESBLs and carbapenemases production using combined disc diffusion and Carba NP tests respectively. Susceptibility of the isolates were checked following CLSI guidelines. PCR assays targeting different resistance genes were performed followed by transformation and conjugation experiments to investigate the transferability of carbapenemase-encoding gene. Whole genome sequencing was carried out using Illumina NovaSeq 6000 platform and the data generated were analysed using bioinformatic tools. Results The Chromobacterium violaceum isolates obtained in the study were harbouring the carbapenemase-encoding gene bla OXA-232 along with the carriage of ESBLs, AMEs and sulphonamides genes. The carbapenemase-encoding gene was carried within a non-conjugative plasmid, however, was found associated with the insertion sequence IS Ecp1 , which was located upstream of bla OXA-232 . The AME gene aac(3)-IIc was found associated with two different insertion sequences ISCpi1 and ISStma1 . The carriage of proteins corresponding pathogenic families, the study isolates were predicted to be a human pathogen (probability of 0.85). The Chromobacterium violaceum isolates harboured extrachromosomal DNA along with intact prophage regions. Conclusions Chromobacterium violaceum harboring the emerging OXA-48 variant bla OXA-232 along with multiple resistance determinants within clinical-environmental interface is a serious health hazard as it might serve as a source and vector for their transmission in different settings, thereby, increasing the antimicrobial resistance burden. The study warrants urgent monitoring of these resistance determinants to thwart their future dissemination.

Source: Indian Journal of Medical Microbiology

DOI: 10.1016/j.ijmmb.2025.100952