ANTIMICROBIAL SUSCEPTIBILITY AND BIOFILM FORMATION PROFILES OF Escherichia coli ISOLATES IN STORED DRINKING WATER FROM THREE COMMUNITIES IN EGOR LOCAL GOVERNMENT AREA, EDO STATE, NIGERIA

Iserhienrhien O.*, Igbinosa E. O., Igbinosa I. H., Unuabonah F. H., Eyaufe A. O.

ABSTRACT

Access to clean and safe drinking water remains a significant challenge in many rural areas, with improper storage and contamination posing serious risks to public health. This study examines various factors influencing the quality of stored drinking water, including sociodemographic characteristics of households, water sources, storage methods, antimicrobial susceptibility and biofilm formation profiles of Escherichia coli isolates in stored drinking water from Ugbiyokho, Evbuotubu and Iguediayi Communities, Egor Local Government Area, Edo State. Nigeria. A combination of classical IMVIC tests and the API 20E system was used for the identification of E. coli, allowing for accurate differentiation from other potentially similar bacteria. Biofilm formation was assessed qualitatively by the tube adherence method and quatitatively by the microtiter plate assay. The research utilized a structured questionnaire (n=400) to collect data on sociodemographic characteristics, water sources, types of storage systems, and the duration of water storage from Ugbiyokho, Evbuotubu, and Iguediayi communities in Egor Local Government, Edo State Nigeria. Among the 118 isolates tested, 66(55.9%) were resistant to ampicillin, while 39(78.1%) displayed resistance to piperacillin. Conversely, combination agents such as amoxicillin-clavulanate and ampicillin-sulbactam demonstrated high sensitivity rates, with 105(88.9%) and 110(93.2%) of isolates susceptible, respectively. No resistance was detected to carbapenems, as all isolates were fully sensitive to imipenem. Among fluoroquinolones, ciprofloxacin showed moderate susceptibility with 72(61%) of isolates sensitive, while 18(15.3%) were resistant. Macrolides, nitrofurans, and fosfomycin displayed strong effectiveness, with susceptibility rates of 95(80.5%), 95(80.5%), and 107(90.7%), respectively. Notably, cephems such as cefotaxime and ceftazidime also exhibited high efficacy, with 107(90.7%) and 110(93.2%) sensitivity, respectively. The tube adherence assay categorized 41(34.7%) of isolates as non-biofilm producers, while 17(14.4%) were weak biofilm producers, 36(30.5%) were moderate biofilm producers, and 24(20.3%) were strong biofilm producers. The microtiter plate assay provided a similar distribution, with 45(38.1%) classified as non-biofilm producers, 13(11%) as weak biofilm producers, 38(32.2%) as moderate biofilm producers, and 22(18.6%) as strong biofilm producers. These results demonstrate that a notable proportion of the isolates had significant biofilm-forming abilities, which could enhance their survival and resistance in hostile environments. The combination of high antimicrobial resistance and biofilm-forming ability among E. coli isolates from household water supplies poses a significant public health threat. These bacteria can persist in stored water, evade treatment, and cause infections that are difficult to manage with commonly available antibiotics. The results highlights the urgent need for improved water treatment and storage practices; regular monitoring of antimicrobial resistance in environmental isolates; public health education on the risks of antibiotic misuse and the importance of safe water handling.

Keywords: Antimicrobial, Profile, Biofilm, Water, Community.