Antibacterial Efficacy of Ficus ottoniifolia and Zanthoxylum zanthoxyloides Leaf Extracts against Bacterial Isolates from Contaminated Drinking Water Sources in Ikwo South, Nigeria

Abstract

Introduction: The contamination of drinking water with pathogenic bacteria poses a significant public health threat, especially in rural areas of developing countries where access to treated water is limited. This study evaluated the antibacterial efficacy of Ficus ottoniifolia and Zanthoxylum zanthoxyloides leaf extracts against bacterial isolates from drinking water sources in Ikwo South, Ebonyi State, Nigeria. Methods: A total of 50 water samples from wells, boreholes, and surface sources across ten communities were analyzed using Standard microbiological techniques, yielding 53 bacterial isolates. Results: Escherichia coli was the most prevalent (43.4%), followed by Staphylococcus aureus (22.6%), Shigella flexneri (18.9%), and Klebsiella pneumoniae (15.1%), indicating significant fecal and environmental contamination. Antibacterial activity was assessed using the agar well diffusion method. The petroleum ether extract of F. ottoniifolia and the ethyl acetate extract of Z. zanthoxyloides demonstrated concentration-dependent inhibition against all test organisms, with the highest activity observed against S. aureus (inhibition zones up to 19.5 mm at 100 mg/mL). Methanol extracts of both plants showed no activity. Minimum inhibitory concentrations (MICs) were lowest for S. aureus (12.5 mg/mL) and higher for Gram-negative isolates (25 mg/mL). Conclusion: The findings confirm the contamination of local water sources with pathogenic bacteria and validate the traditional use of these plants, highlighting the potential of their non-polar extracts as sustainable, locally-sourced agents for water purification or complementary antimicrobial strategies in resource-limited settings.