Occurrence, virulence characteristics and antimicrobial resistance of Escherichia coli O157 in slaughtered cattle and diarrhoeic calves in West Bengal, India

Aims:  (i) To study the occurrence of Escherichia coli serotype O157 in cattle stool in West Bengal, India, and (ii) the virulence properties and antimicrobial resistance of the E. coli isolates. Methods and Results:  Following enrichment in modified EC broth and plating onto HiCrome MS.O157 agar, a total of 14 strains of E. coli serotype O157 was isolated from faecal samples from two (2.04%) slaughtered cattle and six (7.59%) diarrhoeic calves. By multiplex PCR, Shiga toxin genes were detected in all the isolates. The enterohaemolysin phenotype was found in all, but one strain. Among 14 strains, ten were resistant to at least one of the antimicrobial agents tested. Multiple antibiotic resistance was frequent. Conclusions:  The study showed that occurrence of Shiga toxin‐producing and multiple antibiotic‐resistant E. coli O157 among cattle population in this region of India is significant. Significance and Impact of the Study:  Considering routine human contacts with cattle, a large human population in this region may be at risk for exposure to Shiga toxin‐producing E. coli O157.