Prevalence, Antimicrobial Susceptibility, and Resistance Genes of Extended-Spectrum β-Lactamase-Producing Escherichia coli from Broilers Sold in Open Markets of Dakar, Senegal.

Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) poses a significant public health concern due to its widespread prevalence and resistance to multiple antibiotics. This study aimed to assess the prevalence, resistance profile, and carriage of ESBL-encoding genes in ESBL-Ec isolates from broilers in two markets of Dakar, Senegal. Sampling over a one-year period revealed that 61.7% of broilers carried ESBL-Ec in their cecum. Antibiotic susceptibility testing of 186 ESBL-Ec isolates showed high resistance to β-lactam antibiotics, including ampicillin, ticarcillin, and third-generation cephalosporins. Notably, all isolates were susceptible to imipenem. Multidrug resistance was frequent, with 91.4% of the isolates displaying this phenotype. Comparison between the two markets revealed variations in resistance to quinolones. PCR analysis detected blaCTX-M genes in all isolates, with blaCTX-M-1 being the most prevalent subgroup. Additionally, blaTEM and blaOXA genes were found in 26.3% and 2.7% of isolates, respectively, while no blaSHV genes were detected. Combinations of ESBL genes were common, with blaCTX-M15-blaTEM being the most frequent. These findings highlight the widespread prevalence of ESBL-Ec in broilers from Dakar markets, indicating a potential risk of transmission to humans through the food chain. Effective surveillance and intervention strategies are crucial to mitigate the spread of antimicrobial resistance in humans and animals.