BACTERIOLOGICAL ASSESSMENT OF DRINKING WATER FROM DIFFERENT SOURCES IN AGBOR, DELTA STATE

Abstract

This study assessed the bacterial quality of drinking water from four commonly consumed sources in Agbor, Delta State, Nigeria: tap, well, bottled and sachet water. The assessment focused on bacterial load, presumptive identification of bacterial isolates, their distribution among the sampled water sources and antibiotic susceptibility patterns. Fifteen water samples were examined using Nutrient Agar, MacConkey Agar and Eosin Methylene Blue Agar, with colony morphology, Gram staining and biochemical and sugar-utilization tests used for presumptive identification. The colony counts varied substantially among individual samples. Well-water samples generally showed higher bacterial counts, and Sample 6 recorded the highest mean counts on Nutrient Agar (94 colonies), MacConkey Agar (34.3 colonies) and EMB Agar (14.7 colonies). Bottled-water samples generally showed lower counts, although Sample 11 recorded a relatively high Nutrient Agar mean of 85.3 colonies. Ten suspected bacterial isolates were recovered: Corynebacterium sp., Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus, Serratia sp., Klebsiella sp., Enterobacter sp., Citrobacter sp. and two suspected Escherichia coli isolates. Both Gram-positive and Gram-negative organisms were detected, demonstrating considerable bacterial diversity. Antibiotic susceptibility testing showed variable responses, with resistance indices ranging from 0.2 to 0.7. Staphylococcus aureus had the lowest resistance index (0.2), while Klebsiella sp. and the second suspected E. coli isolate had the highest (0.7). Overall, the findings show that microbiological safety could not be assumed solely from water-source type. Regular microbiological monitoring, better protection of wells, improved hygiene during packaged-water production and handling, maintenance of tap-water distribution systems, and attention to antibiotic-resistant bacteria are recommended.