Prevalence and Antimicrobial Resistance Pattern of Shiga Toxigenic Escherichia coli in Diarrheic Buffalo Calves

Aim: Aim of the study was to investigate the prevalence, virulence gene profiles, and antimicrobial resistance pattern of Shiga toxigenic Escherichia coli (STEC) in diarrheic buffalo calves from Andhra Pradesh and Telangana States.

Materials and Methods: A total of 375 fecal samples from diarrheic buffalo calves of 1-7, 8-30, 31-60, and 61-90 days age were collected from which STEC were isolated, and virulence genes were detected using multiplex polymerase chain reaction. The antimicrobial resistance of isolates was tested by disk diffusion method.

Results: The prevalence of E. coli associated diarrhea in buffalo calves was 85.04%, of which 35.01% was STEC origin. In STEC, the combination of eaeA and, hlyA virulence genes was highest (42.45%) followed by stx1 (16.04%), stx1, stx2 and hlyA (13.21%), stx2 (12.64%), stx1, eae and hlyA (9.43%) and stx1 and hlyA (6.6%) genes were detected. Highest antimicrobial resistance was observed for tetracycline (63.21%) and ampicillin (48.11%), while chloramphenicol, gentamycin (96.33%) and imipenem (99.06%) antibiotics are susceptible. Multidrug resistance was detected in 69.81% of the STEC isolates from diarrheic buffalo calves.

Conclusion: Higher prevalence of eaeA and hlyA genes carrying isolates of STEC may be a serious zoonotic threat and increased prevalence of multidrug resistance in E. coli may necessitate stringent selection of appropriate antimicrobial agent in treating buffalo calf diarrhea cases.