Keywords
Enteric bacteria
Mechanical vectors
Synanthropic insects
Vegetable markets
Abstract
This study investigated the role of synanthropic insects as mechanical vectors of enteric and antibiotic-resistant bacteria in two major vegetable markets (Oje and Bodija) in Ibadan, Nigeria. Fresh vegetables, often consumed raw, are highly susceptible to microbial contamination in open-market environments where sanitation infrastructure is limited. Using a cross-sectional design, 1,117 insectscomprising houseflies, cockroaches, ants, and beetleswere collected alongside vegetable samples. Bodija Market accounted for the majority of insect collections (60.52%), though both markets exhibited high ecological diversity across the four taxa. Bacterial isolates were identified using conventional microbiological techniques, including Gram staining and biochemical profiling. Results confirmed the presence of several pathogens, including Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Salmonella enterica, Salmonella typhi, and Shigella dysenteriae, with total viable count loads reaching 1.9 × 10¹⁰ CFU/ml. Antibiotic susceptibility testing, conducted per CLSI (2023) guidelines, revealed near-universal resistance to cephalosporins, cotrimoxazole, and tetracycline. Notably, multidrug-resistant (MDR) phenotypes were documented across multiple species. The study found that insect-derived isolates exhibited higher species diversity and resistance prevalence than those from vegetables, confirming their role as reservoirs and transporters of antibiotic resistance. These findings provide a critical evidence base for the necessity of targeted integrated pest management, improved market sanitation, and enhanced food safety policies to reduce insect-mediated contamination and protect public health in urban settings.
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