Prevalence and Molecular Characterization of Shiga-toxigenic Escherichia coli in Piglets of North East Region of India

Background: Shiga-toxigenic E. coli also known as verotoxin–producing E. coli is one of the diarrhoeagenic E. coli strains which also include its well-known subgroup enterohaemorrhagic E. coli. It is increasingly recognized as the cause of severe gastrointestinal and systemic diseases, such as haemorrhagic colitis and haemolytic uraemic syndrome.

Materials and Methods: The present research study was conducted during 2013-15 to investigate the prevalence and molecular characterization of Shiga-toxigenic Escherichia coli associated with gastroenteritis of piglets in organized and unorganized farms of North East Region of India. A total of 457 faecal samples were collected from unweaned piglets in organized and unorganized farms of North East States of India. All the isolates were screened by multiplex PCR assay for presence of putative virulence genes (stx1, stx2, and hlyA), serotyped and further characterized for resistance against 15 selected antimicrobial drugs.

Results: Of the 1286 E. coli isolates screened by multiplex PCR, a total of 30 isolates (2.33%) were recorded as STEC and were isolated from diarrhoeic piglets only. Of the 30 STEC, 28 isolates were positive for stx2 gene and 2 isolates possessed hlyA gene. Nineteen STEC (2.9%) were recovered from organized farms and 11 (1.74%) from unorganized farms, further, 5 STEC isolates (1.51%) were isolated from local breed and 25 (2.61%) from cross breed piglets. The 30 STEC isolates belonged to 9 different serogroups, 4 isolates (13.33%) were untypable and 5 isolates (16.66%) were rough strains. Serogroups, O1, O8, O156 were found to be the most prevalent serotype (10.0%). All the isolates showed resistance to at least three antimicrobial agents. None of the isolates were found resistance against imipenem, whereas the highest resistance was observed against cefalexin (80.0%) and amoxycillin (76.66%).