Contamination of Drinking Water by Coliform Bateria in Kassala City-Sudan

This study was conducted to investigate the coliform bacterial contamination of drinking water of Kassala city during March to June 2008. Seventy samples of water were taken from seven different areas main station, El-shảbiya, El-halanga, El-ảmriya, El-gasor, El-kara, Elbrno (ten samples each), including chemically treated water from the main station and untreated water from wells. Bacterial coliform contamination was investigated by Multiple fermentation tube technique to detect the existence of total and thermotolerant coliforms at 37◦C and 44◦C, respectively. The total coliform bacteria were detected in 46 (65.7%) samples, while thermotolerant coliform bacteria were detected in 31 (44.3%) samples. A total of 57 isolates were obtained from 46 samples,which were identified according to their microscopic, cultural and biochemical properties as: Escherichia coli(38.6%), Enterobacter aerogenes(17.5%), Enterobacter cloacae(15.8%),Klebsiella pneumoniaesubspecies aerogenes(12.3%), Klebsiella pneumoniaesubspeciesozaenae (8.8%) and Citrobacter freundii(7%). Citrobacter freundiiand Klebsiella pneumoniae ssp.ozaenaewere found in untreated water only. While the other species were found in both treated and untreated water with higher prevalence in untreated water. The wells in the centeral city (El-halanga and El-ảmriya) contained more coliform bacteria, especially Escherichia colithan wells which exist near Gash river (El-gasor) in the side of the cit