Presence of enterotoxigenic Escherichia coli in biofilms formed in water containers in poor households coincides with epidemic seasons in Dhaka

Aims The objective of this study was to investigate if biofilms may be potential reservoirs for the waterborne pathogen enterotoxigenic Escherichia coli (ETEC) in household water in Dhaka, Bangladesh. Methods and Results Biofilms formed on submerged glass slides. Mature biofilms were found significantly more often on glass slides collected in the monsoon period between the two annual ETEC peaks in Bangladesh, that is, between May and August than the rest of the year (P<0 center dot 03). Sixty-four per cent (49/77) of all biofilms analysed by quantitative real-time PCR were positive for ETEC. Significantly more ETEC-PCR positive biofilms were found during the epidemic peaks and during flooding periods than the rest of the year (P<0 center dot 008). Planktonic ETEC was present in the household water during all seasons, but there was no correlation between presence or numbers of ETEC in water and the epidemic peaks. Conclusions We conclude that ETEC is continuously present in water and biofilms in household water reservoirs in Dhaka, which has a high prevalence of ETEC diarrhoea. The frequency of biofilms with ETEC was significantly associated (P<0 center dot 008) with seasonal epidemic peaks of ETEC diarrhoea. Significance and impact of the study We show for the first time that enterotoxigenic Escherichia coli (ETEC), the causative agent of acute watery diarrhoea and travellers' diarrhoea is present in biofilms in household water tanks in Dhaka, Bangladesh.