Escherichia coli contamination and risk exposure assessment of humans consuming water from unprotected wells in Chaona community, Mwachisompola area of Chibombo district of Zambia.

A quantitative cross-sectional study was conducted to detect the presence of E. coli in unprotected water wells of Chaona community in Mwachisompola area, Chibombo District. A total of 48 wells drawn from four villages were sampled from the study area and an exposure assessment was done by use of add-in Model risk app in excel for risk assessment. The occurrence of the bacterium in well water was confirmed by laboratory processes of culturing, isolation and identification of E. coli. The identified E. coli was subjected to microbial resistance testing and the resistant genes
were further detected by use of PCR. Out of 48 unprotected wells tested, 38 were indicative of E. coli presenting 79% (95% CI: 77.3 – 80.7%). The individual variation results that were positive to E. coli are Chilumbwa 5/38 (32%) (95% CI: 2.3 – 23.7%), Chabwa village 10/38 (26%) (95% CI:
12.1– 39.9%), Kafwilo 11/38 (29%) (95% CI: 14.6 – 43.4%) and Katobole12/38 (32%) (95% CI: 17.2 – 46.9%). Meanwhile, 16/48 (33.3%; CI: 31.4 – 35.2%) samples were found with an average number of CFU of between 1000 and 10,000 which was the highest range. E. coli isolates were also tested for Multi Drug Resistance (MDR) of which one isolate was indicative of being resistant to eight antibiotics and another to five antibiotics presenting (5.88%; CI: 3.2 – 8.6%) for each. Meanwhile, seven isolates were resistant to four antibiotics (41.2%; CI: 35.5 – 46.9%) and eight isolates were resistant to three antibiotics (41.1%) (CI: 35.4 – 46.9%). In addition, 30.9% (17/55) of the isolated E. coli organisms were found to be resistant to three or more classes of antibiotics primarily ampicillin, streptomycin, tetracycline, cefotaxime, nalidixic acid, norfloxacin and ciprofloxacin. The probability to be exposed to E. coli was revealed to be at 79.5% (95%; CI: 66.5 – 86.7%) when consuming water from unprotected wells in the study area. In conclusion, the study revealed that E. coli contamination was highly possible and it is recommended that water be boiled and or treated with chlorine before use at household level.