Occurrence, Physicochemical Properties and Antibiotic Resistance Patterns of Enteric Bacteria Isolated from Well Water in Ilara-Mokin, Ondo State, Nigeria

Aims: TheoCcurrence and antibiotic resistance patterns of enteric bacteria isolated from well water sources and their physicochemical profile was ascertained in this study. Molecular analysis of the bacterial isolates from well water samples was conducted via polymerase chain reaction (PCR)-based identification.

Study Design: Experimental design.

Methodology: A total of 12 wells were collected in triplicates from groundwater sources (wells), and mean values were obtained. The first batch of samples were collected during the dry season in January and February, 2020. The second batch of samples were collected during the rainy season in July 2020. The detection of coliforms and other enteric bacteria were conducted via the most probable number (MPN) method. Polymerase chain reaction (PCR)-based identification and characterization of bacterial isolates were employed. Antibiotic susceptibility test was done using the Kirby Bauer disc diffusion technique. The determination of the physicochemical properties of the well water samples were conducted following customary protocol.

Results: Well water sample 7 had the highest count at 250 bacterial counts/100ml in the dry season and 200 bacterial counts/100ml in the rainy season, while well water sample 4, 10, and 11 had 14 bacterial counts/100ml in dry season, well water sample 2 had 140 bacterial counts/100ml in the dry season and 250 bacterial counts/100ml in the rainy season, whilst sample 11 had 7 bacterial counts/100ml in the rainy season. Klebsiella pnuemoniae, Escherichia coli, Salmonella typhi and Shigella dysentariae were the Gram-negative organisms enumerated and molecularly-identified as Klebsiella pnuemoniae subsp. Pnuemoniae HS11286, Escherichia coli 0157:H7, Salmonella enterica subsp. Enterica serovar typhimurium and Shigella dysentariae HNCMB 20080 from the well water samples with percentage identity of 97.19%, 87.44%, 80.45% and 96.19% respectively. Klebsiella pnuemoniae showed high resistant rate in augmentin at 67% in dry season and 100% in the rainy season. Shigella dysentariae showed 8.3% resistance to augmentin in the dry season and 75% in the rainy season. E. coli showed 67% and 58% resistance in the dry and rainy season respectively. Water hardness had the highest mean of 98.5 and 99.5 mg/L in dry and rainy season respectively while turbidity, and alkalinity had the least mean value at 1.2 (NTU) and 0.62 mg/L, 1.4 (NTU) and 0.7mg/L in both dry and rainy seasons.

Conclusion: Findings provided information on the poor quality of the well water, which will be useful in groundwater treatment strategies and policy formulation by appropriate groundwater source protection bodies.