Prevalence and molecular characterisation of extended-spectrum β-lactamases genes in Escherichia coli and Salmonella spp. isolated from fish samples in Chhattisgarh, India

In this study, fish samples were examined for the presence of extended spectrum beta-lactamases (ESBL) producing Escherichia coli and Salmonella spp. Out of 200 samples collected from retail markets of Durg, Raipur, Rajnandgaon and Balod districts of Chhattisgarh State, 76 (38) and 46 (23%) samples were found contaminated with E. coli and Salmonella spp., respectively. Multiple antibiotic resistant (MAR) index varied between 0.00 to 0.88 and 0.11 to 0.88 for E. coli and Salmonella isolates, respectively. The isolates were screened phenotypically for ESBL production and multiplex PCR targeting bla(TEM), bla(SHV), and bla(CTX-M) genes, was carried out followed by sequencing. Prevalence of bla(TEM), bla(SHV) and bla(CTX-M) genes in E. coli and Salmonella isolates were found to be 13.2, 1.3, 0 and 6.5, 0, 4.4%, respectively. Higher percentage of resistant genes was detected in plasmid DNA in comparison to genomic DNA. Sequencing of PCR amplicons of bla(TEM) and bla(CTX-M) genes revealed the presence of bla(TEM-116) and bla(CTX-M-15) variants, respectively. The study indicates the presence of multidrug resistant ESBL producing E. coli and Salmonella in fish samples, which may pose threat to the fish consumers.