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 <i>Escherichia coli</i> (ESBL-<i>Ec</i>) 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-<i>Ec</i> isolates from broilers in two markets of Dakar, Senegal. Sampling over a one-year period revealed that 61.7% of broilers carried ESBL-<i>Ec</i> in their cecum. Antibiotic susceptibility testing of 186 ESBL-<i>Ec</i> 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 <i>bla_CTX-M</i> genes in all isolates, with <i>bla_CTX-M-1</i> being the most prevalent subgroup. Additionally, <i>bla_TEM</i> and <i>bla_OXA</i> genes were found in 26.3% and 2.7% of isolates, respectively, while no <i>bla_SHV</i> genes were detected. Combinations of ESBL genes were common, with <i>bla_CTX-M15-bla_TEM</i> being the most frequent. These findings highlight the widespread prevalence of ESBL-<i>Ec</i> 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.