Three hundred and twenty-six Escherichia coli isolates recovered from 326 human faecal specimens from sporadic cases of diarrhoea in Kashmir valley, India, were investigated for the presence of stx(1), stx(2), eaeA, hlyA and lt virulence genes. None of the samples was positive for stx genes or Shiga toxins by PCR or enzyme-linked immunosorbent assay. Twenty-three E. coli isolates showed the presence of the eaeA gene, whereas three isolates harboured the lt gene. Enteropathogenic E. coli (EPEC) belonged to 10 different serogroups. Out of 23 EPEC isolates, the majority (78.26%) were atypical while five (21.73%) were typical. Only one of the typical EPEC harboured the EAF plasmid. Subtyping of the eaeA gene showed the presence of eaeA-alpha(1), eaeA-beta, eaeA-xi and eaeA-eta in one, two, four and two isolates, respectively. None of the E. coli isolates possessed eaeA-delta, eaeA-epsilon and eaeA-zeta. This study further upholds the opinion that Shiga toxin-producing E. coli do not pose a major threat to human health in India and eaeA-alpha(1), eaeA-beta, eaeA-xi and eaeA-eta could be common EPEC subtypes prevalent in humans with diarrhoea in India. The present study appears to be the first report of subtype analysis of the eaeA gene from India and also records the isolation of EPEC with the eaeA-xi gene from humans.
Aims: To determine the subtypes of stx and eae genes of Shiga toxin‐producing Escherichia coli (STEC) and enteropathogenic Escherichia coli (EPEC) from calves and to ascertain the typical and atypical nature of EPEC.
Methods and Results: One hundred and eighty‐seven faecal samples from 134 diarrhoeic and 53 healthy calves were investigated for the presence of stx, eae and ehxA virulence genes by polymerase chain reaction and enzyme‐linked immunosorbent assay. Subtype analysis of stx1 exhibited stx1c in 13 (31·70%) isolates, while that of stx2 revealed stx2c in eight (24·24%) and stx2d in two (6·06%) isolates. Subtyping of eae gene showed the presence of eae‐β, eae‐η and eae‐ζ in two, three and four isolates respectively. None of the E. coli isolates possessed stx2e, stx2f, eae‐α, eae‐δ, eae‐ε and eae‐ξ. All EPEC isolates were atypical.
Conclusions: stx
1
, stx1c, stx2, stx2c, stx2d, eae‐β, eae‐η and eae‐ζ subtypes are prevalent in STEC and EPEC isolates in India.
Significance and Impact of the Study: This is the first subtype analysis of stx2 and eae genes of animal E. coli isolates in India and emphasizes the need to investigate their transmission to humans.
Seven hundred and thirty-five diarrhoeic faecal samples from children were investigated for presence of enteroaggregative E. coli (EAEC), enterotoxigenic E. coli (ETEC), diffusely adherent E. coli (DAEC) and Salmonella spp. by polymerase chain reaction (PCR) and bacterial culture. Out of 675 samples from Kashmir, 55 isolates were obtained, which carried at least one virulence gene studied. Out of the 55 isolates, 36 (65.45%) were EAEC, 18 (32.72%) were ETEC while only one isolate (1.81%) was DAEC. All the EAEC isolates were found to be typical as they possessed aggR gene. Six (16.66%) EAEC isolates carried the astA gene. Out of the 18 ETEC isolates, 13 carried the elt gene alone, four possessed both the elt and est genes and the remaining one harboured the est gene alone. Five ETEC isolates also possessed astA gene. Nineteen EAEC isolates belonged to 10 different serogroups. Serogroup O153 was most frequent. The ETEC isolates also belonged to 10 different serogroups of which O159 was most predominant. Out of 224 E. coli isolates from 60 samples of Secunderabad, 27 isolates carried at least one virulence gene. Out of 27 isolates 22 (81.48%) were typical EAEC, three (11.11%) were ETEC and two (7.4%) were DAEC. Fifteen EAEC isolates belonged to seven different serogroups with O86 as most frequent. Four EAEC isolates also possessed the astA gene. All the three ETEC isolates harboured elt gene only and belonged to three different serogroups. Two isolates of Salmonella Worthington were obtained from only two samples in Kashmir.
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