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Page No. : 11-15

ABSTRACT

A study was undertaken to assess the prevalence, serotypes, and virulence genes (stx1 and stx2 through PCR) of E. coli. A total of 405 samples comprising 155 faecal samples, 100 milk samples and 150 milk product samples were screened for E. coli. Out of 405 samples processed, 147 E. coli isolates were obtained. The highest occurrence was observed in faecal sample (60%) followed by milk (22%) and milk products (21.33%). Serotyping results showed that out of 147 E. coli isolates, 18 isolates were rough, 19 isolates were untypable and 110 isolates belonged to 24 different ‘O’ serogroups. Serogroups O55 and O60 were obtained from all the three sources. A total of 110 E. coli isolates (faeces-70, milk-20, milk products-20) were screened by PCR to detect virulence genes stx1 and stx2. Out of 110 isolates tested, 1 isolate (O55) from faeces of diarrhoeic cow was positive for stx1 gene whereas, 1 isolate (O60) from faeces of non-diarrhoeic cow revealed the presence of stx2 gene, while 1 isolate (O172) from faeces of diarrhoeic calf was found to be positive for both stx1 and stx2 gene. None of the samples from milk and milk products were found to be positive for the above-mentioned virulence genes. Thus, on the basis of PCR the prevalence of VTEC in faecal sample was found to be 4.28% (3 out of 70). However, no VTEC was detected from milk and milk products. Thus, the overall occurrence of VTEC in the present study was found to be 2.72% (3 out of 110 isolates).

Keywords: E. coli, faeces, milk, milk products, PCR, VTEC