Phenotypic and genotypic characterization of pathogenic Escherichia coli identified in resistance mapping of β-lactam drug-resistant isolates from seafood along Tuticorin coast

The ubiquity of pathogenic E. coli isolate possessing antimicrobial resistance was investigated in seafood samples procured from major seafood supply chain markets established for export and domestic consumption along Tuticorin coast. Out of 63 seafood samples examined, 29 (46%) were found to be contaminated by pathogenic E. coli harbouring one or more genes of virulent potential. Based on virulome profiling, 9.55% of isolates belonged to enterotoxigenic E. coli (ETEC), 8.08% to enteroaggregative E. coli (EAEC), 7.35% to enterohemorrhagic E. coli (EHEC), 2.20% to enteropathogenic E. coli (EPEC), and 2.20% to uropathogenic E. coli (UPEC). All the 34 virulome positive and haemolytic pathogenic E. coli have been serogrouped as O119, O76, O18, O134, O149, O120, O114, O25, O55, O127, O6, O78, O83, O17 and clinically significant O111, O121, O84, O26, O103, and O104 (non-O157 STEC) serotypes in this study. Multi-drug resistance (MDR) (>= 3 antibiotic classes/sub-classes) was exhibited in 38.23% of the pathogenic E. coli, and 17.64% were extensive drug resistant (XDR). Extended spectrum of beta-lactamase (ESBL) genotypes were confirmed in 32.35% isolates and 20.63% isolates harboured ampC gene. One sample (Penaeus semisulcatus) collected from landing centre (L1) harboured all ESBL genotypes bla(CTX-M), bla(SHV), bla(TEM), and ampC genes. Hierarchical clustering of isolates revealed the separation of ESBL isolates into three clusters and non-ESBL isolates into three clusters based on phenotypic and genotypic variations. Based on dendrogram analysis on antibiotic efficacy pattern, carbapenems and beta-lactam inhibitor drugs are the best available treatment for ESBL and non-ESBL infections. This study emphasizes the significance of comprehensive surveillance of pathogenic E. coli serogroups that pose serious threat to public health and compliance of AMR antimicrobial resistant genes in seafood that hinder seafood supply chain.