DETECTION OF CARBAPENEM RESISTANCE AMONG THIRD-GENERATION CEPHALOSPORIN-RESISTANT ENTEROBACTERALES FROM SMALL-SCALE POULTRY FARMS IN PERI-URBAN LUSAKA, ZAMBIA.

Background Carbapenem and third-generation cephalosporin (3GC) resistance among Enterobacterales pose a serious threat to human and animal health. This study aimed to identify and characterize carbapenem- and 3GC-resistant Enterobacterales isolated from poultry in Lusaka Province, Zambia. Methods A total of 90 pooled cloacal (n = 45) and meat (n = 45) samples collected from market-ready broiler chickens in Chongwe and Chilanga districts of Lusaka Province were screened for carbapenem- and 3GC-resistant Enterobacterales, followed by antimicrobial susceptibility testing. PCR and Sanger sequencing were used for species identification and detection of the β-lactamase-encoding (bla) genes. Results A total of 83/90 (92.2%) 3GC-resistant Gram-negative strains were isolated from 90 pooled samples, of which 12% (10/83) were also resistant to carbapenems. The most prevalent species was Escherichia coli (57/83, 68.7%), followed by Klebsiella pneumoniae (6/83, 7.2%) and Enterobacter spp. (6/83, 7.2%), then Pseudomonas aeruginosa (4/83, 4.8%), other Pseudomonas spp. (4/83, 4.8%), Acinetobacter baumannii (3/83, 3.6%), Citrobacter freundii (2/83, 2.4%), and Aeromonas caviae (1/83, 1.2%). Multidrug resistance (MDR) was observed in 70/83 (84.3%) of the isolates, with the highest resistance to ampicillin, tetracycline, and co-trimoxazole. A total of 67/83 (80.7%) of the isolates harbored at least one of the four tested bla genes (blaCTX-M, blaTEM, blaOXA-1 and blaSHV), with blaCTX-M (66.2%) and blaTEM (49.4%) being the most common. Conclusions The study analyzed poultry-associated 3GC- and carbapenem-resistant Enterobacterales and found a high prevalence of MDR involving commonly used antibiotics. In addition, some isolates were resistant to imipenem, a last resort drug. Four bla genes (blaCTX-M, blaTEM, blaOXA-1, and blaSHV) were found, with blaCTX-M and blaTEM dominating. Prudent antimicrobial use should be implemented to manage AMR in poultry farming.