Bacteriological examination of Obibia stream during wet and dry seasons in Awka, Anambra State, Nigeria

Diseases caused by contaminated water consumption are among the leading causes of death in children, the elderly, and people who are immunocompromised. Hence there is an important need to ensure that drinking water sources are free from pathogens that can endanger the health of consumers. This study was undertaken to investigate the influence of seasonal changes on the bacteriological distribution of the Obibia stream. A total of 30 water samples (500 ml each) were collected for the study at rainy and dry seasons for a period of May to July 2015 and December 2015 to Feb 2016, respectively. Bacteria present in the water samples were isolated and characterized using 16s rDNA sequencing. Total heterotrophic aerobic bacterial counts were determined using standard microbiological biochemical procedures. Their frequencies of occurrence were also determined. Total heterotrophic aerobic bacterial counts (THABC) were significantly higher (P=0.039) > total coliform count > fecal coliform counts > Salmonella - Shigella counts > Vibrio counts throughout the periods of sampling in the wet season, with the highest counts obtained in July. THABC was also significantly higher (P = 0.018) than other examined bacterial groups and had its peak in January. Bacterial genera present in the examined samples were identified as Shigella, Salmonella, Escherichia coli, Vibrio, Enterobacter, Klebsiella, Enterococcus, Staphylococcus, Pseudomonas, and Serratia with their respective frequencies of occurrence as 4.55%, 18.18%, 13.64%, 27.27%, 4.5%, 9.09%, 4.55%, 4.55%, 9.09% and 4.55% in the wet season. Their respective occurrences in dry season were 4.17%, 16.67%, 12.50%, 25.00%, 4.17%, 8.35%, 4.17%, 8.33%, 8.33%, and 8.33%. This bacteriological analysis has shown that wet season samples from the Obibia stream had more bacterial counts than dry seasons. Thus, the water samples from it require further purification steps before being used for domestic purposes by the inhabitants of its surrounding communities.