Antimicrobial resistance profiles and antibiotic resistance gene detection in environmental isolates from urban streams in Ilorin, Nigeria: a One Health cross-sectional assessment

Urban streams in sub-Saharan Africa receive continuous inputs of untreated wastewater and solid waste, potentially promoting accumulation of antibiotic-resistant bacteria (ARB) and resistance genes (ARGs). Data linking community sanitation to environmental antimicrobial resistance (AMR) in West African cities remain sparse. We assessed physicochemical quality, bacteriological contamination, antibiotic susceptibility, ARG prevalence, and sanitation practices across six urban streams in Ilorin, Nigeria. Three weeks of sampling yielded 247 isolates tested against six antibiotics; 98 multidrug-resistant (MDR) Gram-negative isolates were PCR-screened for five ARGs; seven isolates were 16S rRNA-sequenced; 180 households were surveyed to compute a Composite Sanitation Score (CSS) per catchment. All streams deviated from WHO/NSDWQ reference values. Ampicillin resistance was 64–89% per site; MDR prevalence was 43–68%. bla TEM was most prevalent (58–82%), followed by tet A (46–74%) and int I1 (39–61%). CSS correlated strongly negatively with all five AMR indicators (ρ = − 1.00; exact permutation p = 0.003; Bonferroni α = 0.01). With only six catchments, these are exploratory ecological associations, not causal evidence. Sanitation quality is associated with environmental AMR burden in Ilorin streams, supporting WASH investment within One Health AMR strategies, subject to confirmation in larger multi-site studies.