The occurrence of Enterobacteriaceae in the well water of Nallur Divisional Secretariat area of Jaffna district, Sri Lanka

Abstract

The access for safe drinking water has become a challenge to human at present due to contamination with the different sources of pollution such as domestic waste, animal excreta and latrine leakage. Therefore, this study was carried out with the focus of determining the microbial quality of dug well water from a highly populated peri-urban area (Nallur Divisional Secretariat) of the Jaffna district in Sri Lanka. The water samples from 20 dug wells were collected from the study area and the information particularly the distance of well from the toilet septic tank, sanitary conditions of well and the surroundings were gathered. The total bacterial count was determined and different bacterial species were identified on Xylose Lysine Deoxycholate (XLD) agar.The t-test was performed to identify the factor/s that significantly influences the total bacterial count. A correlation analysis was performed between the distance of well from septic tank and bacterial count. Nine different bacterial species, that belong to the family Enterobacteriaceae, were identified; Klebsiella, Enterobacter, Escherichia, Salmonella, Shigella, Citrobacter, Yersinia, Serratia and Acinetobacter. Of the 72 bacterial isolates from 20 wells, 37 belong to the coliform group indicating recent faecal contamination. The total bacterial count has an inverse correlation with the distance of the toilet from the well (R 2 =0.506). Presence of pathogenic bacteria in the well water in the study is a great threat for human health and therefore, regular measures need to be taken to disinfect the water.