Escherichia coli is a commensal organism of the digestive tracts of many
vertebrates, including humans. Contamination of drinking water with
pathogenic E. coli is a serious public health concern. This study focused on
the distribution of phylogenetic groups and virulence gene profile of E. coli
isolated from drinking water in Arichpur, a low income area of Dhaka,
Bangladesh. The distribution of the phylogroups and virulence genes were
investigated in 200 isolates among them 110 isolates were from municipal
water supply system and 90 were from household drinking water. Gene
profile of virulence factors was done based on the presence of eltB, estA,
vt1, vt2, eaeA, pCVD432, bfpA, ial, ipaH by PCR. The classification of the
isolates into 4/5 major groups (A, B1, B2, D2, D3) was done based on the
distribution of chuA, yjaA and DNA fragment tspE4.C2 genes. Results
demonstrated predominance of phylogroup B1 78.5 % (157/200) followed
by B2 phylogroup 13% (26/200) and phylogroup D 8.5% (17/200).The genes
eltB, estA and eaeA was present in 27.39% (43/157), 37% (74/157), and
10.5% (21/157) of B1 phylogroup isolates, respectively. The calculated chisquare value and P-value were 10.23 and 0.001. Therefore, it can be
inferred municipal water supply was a greater contributor of pathogenic E.
coli from the B1 phylogroup. Usually commensals fall in the Phylogroups A
and B1. The presence of greater number of virulent B1 phylogroup isolates
originating from municipal water supply indicates that the supply system
might be contaminated with virulent E. coli such as enterotoxigenic E. coli
carrying mobile genetic elements such as plasmids which might be
transferred to the commensal strains