Abstract

Municipal solid wastes represent important environmental reservoirs for antimicrobial-resistant bacteria and may facilitate the dissemination of resistance determinants within communities. This study investigated the in-vitro susceptibility of Enterobacterales recovered from municipal solid wastes in Okada, Edo State, Nigeria, to selected cephalosporins, aminoglycosides, and macrolides. Municipal solid-waste samples were collected from Igbinedion University Campus, hostel areas, and Okada Town and subjected to standard microbiological procedures for isolation and identification of Enterobacterales. Total coliform counts varied significantly among sampling locations, ranging from 8.75 × 10⁵ to 1.70 × 10⁷ CFU/g. The University Hostel recorded the highest mean concentration (7.14 ± 0.08 log₁₀ CFU/g), followed by Okada Town (6.24 ± 0.05 log₁₀ CFU/g) and University Campus (cafeteria and food-service areas) (6.07 ± 0.12 log₁₀ CFU/g) (p < 0.05). A total of 72 bacterial isolates were recovered, and their order of decreasing frequency (%) was; Proteus spp. (63.89%) > Klebsiella spp. (18.06%) > Pseudomonas spp. (8.33%) > Escherichia spp. (6.94%) > Enterobacter spp. (2.78%). Antimicrobial susceptibility test revealed pronounced resistance to several cephalosporins, with cefotaxime, ceftazidime, cefotaxime–clavulanic acid, ceftazidime–clavulanic acid, cefuroxime and ceftriaxone each recording 100% resistance. Resistance was comparatively lower to cefazolin (63.89%), amoxicillin–clavulanic acid (59.72%) and cefoxitin (52.78%). Meropenem showed greater activity, with 18.06% resistance, while gentamicin (5.56%), pefloxacin (2.78%) and ofloxacin (0%) exhibited the lowest resistance rates. MAR indices ranged from 0.52 to 0.67, with overall location-specific values of 0.56. The findings demonstrate substantial bacterial contamination and a high antimicrobial-resistance burden in municipal solid wastes, highlighting the need for improved waste management, environmental sanitation and antimicrobial-resistance surveillance in Okada