Incidence of carbapenem-resistant Escherichia coli ST2437 of clinical origin harbouring blaOXA-144 gene: a report from India.

Abstract

Carbapenem-resistant Escherichia coli has been categorized as a pathogen of critical priority by the World Health Organization as they are highly infectious with high mortality and morbidity rates and widespread transmission potential. Carbapenem resistance is primarily mediated by carbapenemase-encoding genes and additionally through intrinsic factors. In India, over the years, carbapenemase-encoding genes have been reported from diverse clinically significant pathogens. The present study identifies E. coli of clinical origin that harbours blaOXA-144. The study isolate was obtained from a tertiary referral hospital in north-east India. Carbapenemase production was investigated through culture on chromogenic agar and Rapidec Carba NP test as per manufacturer's instructions. Susceptibility of the isolate was performed by the Kirby-Bauer disc diffusion method and agar dilution method following CLSI guidelines. PCR targeting carbapenemase-encoding genes was performed followed by transformation and conjugation experiments. Whole Genome Sequencing of the isolate was done through the Illumina sequencing platform and the data were analyzed using the Centre for Genomic Epidemiology database. BJD_EC180 is 6,919,180 bp in length and consists of six rRNA operons, 111 tRNA and 6,849 predicted protein-coding sequences. BJD_EC180 belonged to ST2437 and harboured the carbapenemase-encoding gene blaOXA-144 with ISAba1 upstream, along with multiple antibiotic resistance genes conferring clinical resistance towards beta-lactams, aminoglycosides, amphenicols, sulphonamides, tetracyclines, trimethoprim and rifampin. Carbapenem-resistant E. coli harbouring blaOXA-144 associated with insertion sequence pose a serious health threat as their mobilization into carbapenem non-susceptible strains that will contribute to the resistance burden and therefore, needs urgent monitoring.