Phenotypic Detection of Extended-Spectrum β-Lactamases (ESBLs), AmpC β-Lactamases, and Metallo-β-Lactamases (MBLs) in Pseudomonas aeruginosa Isolated from Drinking Water Sources at Iyi-Oka Spring and Unwana Beach, Afikpo North Local Government Area, Ebony

This study phenotypically detected extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase, and metallo-beta-lactamase (MBL) production in Pseudomonas aeruginosa isolated from Unwana Beach and Iyi-Oka river water in Afikpo North LGA, Ebonyi State, Nigeria. Twenty water samples, ten from each site, were collected and analyzed using standard microbiological and biochemical methods, while antimicrobial susceptibility testing and enzyme detection were performed by Kirby-Bauer disc diffusion in line with CLSI guidance. The total bacterial load was high in both sources, with counts ranging from 3.4×1053.4 \times 10^53.4×105 to 21.1×10821.1 \times 10^821.1×108 CFU/ml in Iyi-Oka samples, while Unwana samples were reported as too numerous to count at the tested dilutions. P. aeruginosa was recovered from 17 of 20 samples (85%), with 70% positivity in Unwana River and 100% in Iyi-Oka River. The isolates showed greatest resistance to amoxicillin/clavulanic acid, oxacillin, cefoxitin, imipenem, aztreonam, and ceftazidime, but remained susceptible to gentamicin, amikacin, and ofloxacin. AmpC and ESBL were detected in both river isolates, whereas MBL was not detected. These findings suggest contamination of the water sources with multidrug-resistant P. aeruginosa and highlight a public health risk associated with untreated drinking water.