Molecular and phenotypic characterization of shigatoxigenic Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) from piglets and infants associated with diarrhoea in Mizoram, India

Abstract

Limited information is available on shiga toxin producing Escherichia coli (STEC) in pigs and infants from Aizawl, Mizoram and North Eastern region of India. This cross sectional study was conducted on faecal samples from pigs and infants to detect and characterize of STEC and enteropathogenic E. coli (EPEC). Serogrouping, molecular and phenotypic characterizations were done by standard molecular and cytotoxic assays. Out of 48 E. coli strains isolated from 320 diarrhoeic fecal samples of piglets, 44 belonged to 18 different serogroups, 3 (6.25%) were untypeable (UT) and 1(2.08%) was recorded as rough strain (R). Similarly, out of 17 E. coli strains isolated from 264 diarrhoeic fecal samples of infants, 16 belonged to O60 (94.1%) and 1(5.88%) was untypeable. Virulence genes (stx1, stx2, eaeA and hlyA) were detected by multiplex PCR assay. A total of 1260 E. coli were isolated from piglets (720) and infants (540) from 584 faecal samples. All together, 5.16% (65) E. coli isolates were found to be positive for at least one virulence gene (6.66% piglets and 3.15% infants). Out of the virulent gene positive E. coli 3.17% (32 from piglets and eight from infants) and 1.98% (16 from piglets and nine from infants) were recorded as STEC and EPEC, respectively. On the other hand, from the total 2.14% stx₂ positive isolates, 16 and 11 were positive for stx_2e and stx_2c subtypes, respectively. Similarly, from the 4.04% eaeA positive isolates, 1.19% (15) were positive for bfpA gene, of which 1.67% (12) were piglets and 0.60% (3) were infants. All the isolates were exhibited varying degree of CPE on vero cell lines. In conclusion, STEC and EPEC seem to be associated with diarrhoea in piglets and infants in Mizoram. In piglets STEC strains represent as a major cause of diarrhoea while EPEC strains represent as major cause of diarrhoea in infants in North Eastern region of the India.

Keywords: Enteropathogenic E. coli (EPEC), infants; piglets, shigatoxigenic E. coli (STEC), vero cell cytotoxicity

African Journal of Biotechnology, Vol 13(12), 1452-1461