Prevalence of Colistin-Resistant Bacteria in Water Sources in Wa, Upper West Region of Ghana

Background and Objective: Antimicrobial resistance is a major global public health threat, with the highest mortality rate in Sub-Saharan Africa. Colistin is considered the last line of defense against multidrug-resistant Gram-negative pathogens. This study sought to assess the prevalence of colistin-resistant bacteria in water sources in the Wa Municipality of the Upper West Region of Ghana.Materials and Methods: A cross-sectional study was conducted, collecting 40 water samples from boreholes, wells and taps in four communities within the Wa Municipality. Samples were cultured and isolates were identified using standard biochemical tests. Colistin susceptibility was assessed using Kirby-Bauer disk diffusion and microbroth dilution techniques, with results interpreted using EUCAST standards. Data was analysed using SPSS version 28. Results: Diverse Gram-negative enteric organisms were isolated, including Citrobacter species (28.5%), Klebsiella species (25%), Serratia marcescens (21.4%), and others. Microbroth dilution testing revealed 44.8% of isolates were colistin-resistant, compared to only 4.7% by disk diffusion. Resistant organisms were found across all communities and water sources. Urban areas showed a significant association with colistin resistance (p = 0.049). Conclusion: High colistin resistance in Wa water sources indicates sanitation challenges. Improved water treatment and antibiotic stewardship are crucial. Ongoing surveillance is recommended.