Seasonal Variation and Antibiotic Susceptibility Patterns of Bacteriological Parameters in Groundwater Sources in Oyi LGA, Anambra State, Nigeria

Potable water is essential for health and survival of all life forms. Contamination of groundwater sources by microbes, organic and inorganic matter has continued to negatively affect the well-being of most people in developing countries such as Nigeria. Thus, this study aimed to determine the seasonal variation and antibiotic susceptibility patterns of bacteriological parameters in groundwater sources in Oyi LGA, Anambra State, Nigeria. Hand-dug well and borehole water sites were randomly selected in five communities of Oyi LGA, and water samples were aseptically collected and analyzed using standard microbiological procedures. The total heterotrophic counts of bacteria isolated from groundwater samples during both seasons were between 1.3×102 and 2.87×104 CFU/mL, total coliform counts ranged from 2 to 165 MPN/100mL and faecal coliform ranged from 0 to 32 MPN/100mL. Probable bacterial isolates in groundwater samples were Escherichia coli, Klebsiella aerogenes, Shigella flexneri, Enterococcus faecalis and Enterobacter sp. Seasonal variations showed there were more bacterial loads in sampled water during wet season than dry season. Antibiotic susceptibility test revealed that all the bacterial isolates were sensitive to Levofloxacin and Ofloxacin, and are recommended for treatment of diseases caused by some of these pathogens. Shigella flexneri exhibited highest susceptibility (60%) to the antibiotics, while Enterobacter faecalis showed highest resistance (70%). Escherichia coli exhibited 50% susceptibility and 50% resistance. The sampled water sources did not meet the WHO and NSDWQ guidelines for drinking water, and therefore not fit for human consumption without adequate treatment.