Occurrence of cefotaxime-resistant and beta-lactamase-producing Enterobacterales in poultry from small-scale farms in the Copperbelt province of Zambia.

Background: The inappropriate use of antimicrobials in poultry farming is associated with the emergence of antimicrobial-resistant Enterobacterales. This cross-sectional study aimed to identify various cefotaxime-resistant and β-lactamase-producing Enterobacterales and characterize their antimicrobial resistance profiles.

Methods: Pooled cloacal and meat samples collected from market-ready broiler chickens in Kitwe and Ndola districts of Zambia were screened for cefotaxime-resistant Enterobacterales. The samples were inoculated on MacConkey agar supplemented with 1 mg/L cefotaxime. The cefotaxime-resistant isolates were further subjected to antimicrobial susceptibility tests. Further, the isolated cefotaxime-resistant Enterobacterales were analysed for , , and genes using PCR and Sanger sequencing.

Results: From a total of 114 pooled samples, 81 (71.1%) cefotaxime-resistant Gram-negative strains were isolated. These were dominated by (77.8%) followed by (6.2%), spp. (6.2%), (4.9%), (2.5%), spp. (1.2%) and (1.2%). Furthermore, 64.2% of the 81 isolates exhibited multidrug resistance with high resistance (>64%) to ampicillin, co-trimoxazole and tetracycline. The results also showed that 66.7% of the isolates harboured at least one of the four tested genes ( , , and ), with the commonest being (58%) and (45.7%).

Conclusions: The study revealed a high prevalence of cefotaxime-resistant Enterobacterales and multidrug resistance involving medically important antibiotics. Four genes ( , , and ) were identified. Our results highlight the need to strengthen antimicrobial stewardship programmes and optimize antimicrobial use in poultry farming.