Detection of diarrhoeagenic Escherichia coli in the abattoir wastewater-impacted Iyi-Etu River and other water types at the Amansea livestock market settlement, Anambra State, Nigeria: a matter of public health concern.

Background: Globally, diarrhoeagenic Escherichia coli (DEC) has been implicated in the spread of waterborne diseases and abattoir wastewater has played a role in its dissemination into watersheds. This study isolated and characterised DEC from the abattoir wastewater-impacted Iyi-Etu River and other water sources at the Amansea livestock market settlement.

Methods: A total of 96 water samples comprising river water (upstream, downstream 1, downstream 2), borehole, well, sachet and abattoir wastewater samples were tested for DEC. In the inoculation process, membrane filtration was used, and selective media such as Eosin Methylene Blue, Chromoselect agar and Sorbitol Maconkey agar were used to screen for E. coli and Shiga toxin-producing E. coli (STEC) O157. Escherichia coli pathotypes were characterised using molecular techniques.

Results: Overall, E. coli was presumptively detected in 28.1% (27/96) of all samples. Of the 27 isolates, three (11.1%) were non-sorbitol fermenters (typical of E. coli O157), while 20 (74.1%) were confirmed as E. coli based on uidA housekeeping gene positivity. The detected circulating pathotypes were enteropathogenic E. coli (EPEC) (35.0%; 7/20), enteroinvasive E. coli (EIEC) (40.0%; 8/20), enterotoxigenic E. coli (15.0%; 3/20), STEC (40.0%; 10/20) and enteroaggregative E. coli (5.0%; 1/20). Escherichia coli as well as EPEC, EIEC and STEC pathotypes were most prevalent at the downstream 1 sampling point compared with the upstream. EPEC, EIEC and STEC were also detected in borehole samples (5.0%, 1/20).

Conclusions: The Iyi-Etu River and borehole water sources used for domestic and drinking purposes, respectively, at Amansea livestock market settlement are contaminated with some pathotypes of E. coli and the level of pollution may pose a public health risk to humans and animals during contact. Thus, public health measures including proper treatment of wastewater before disposal and continuous monitoring may help to learn the associated effect of DEC pollution in the area.