Molecular characterization of extended-spectrum β-lactamase–producing Escherichia coli from abattoir and live bird market wastewaters in Kaduna State, Nigeria

The increasing misuse and overuse of antibiotics in livestock have been a serious challenge, leading to the spread of drug-resistant pathogens, especially extended-spectrum β-lactamase (ESBL)-producing Escherichia coli which is a particular concern in developing countries. This study investigated the occurrence, antimicrobial resistance patterns, and ESBL gene profiles of E. coli isolated from abattoir and live-bird market wastewater in Kaduna State, Nigeria. A total of 48 wastewater samples were collected from eight sites across Kaduna North and South. Presumptive E. coli species were isolated using standard microbiological methods and subjected to antibiotic susceptibility testing, phenotypic ESBL confirmation, and molecular detection of the ESBL gene. Twenty-three E. coli isolates were recovered, comprising 13 (56.5%) from live bird markets and 10 (43.5%) from abattoirs. All isolates exhibited multidrug resistance, with multiple antibiotic resistance indices exceeding 0.2. Phenotypic testing confirmed ESBL production in all isolates. Four live bird market isolates and two abattoir isolates had at least one ESBL gene (TEM, SHV, and CTX-M). Among the ten isolates examined, blaTEM was the most common gene (60%), and two isolates harbored multiple ESBL genes. TEM, SHV, and CTX-M genes were present in isolate KKA1b (abattoir source), whereas TEM and CTX-M genes were present in isolate CLB3a (live bird market source). These findings demonstrate that abattoir and live bird market wastewaters in Kaduna State serve as important environmental reservoirs of multidrug-resistant ESBL-producing E. coli, underscoring the need for improved waste management practices and continuous antimicrobial resistance surveillance.