Multidrug-resistant Enterobacterales in commercial laying and free-range hens (Gallus gallus domesticus) under semiarid conditions of the Caatinga biome.

内容摘要

Antimicrobial resistance (AMR) is considered one of the greatest challenges to global health and a direct threat to human, animal, and environmental health. Thus, the objective of this survey was to characterise the antimicrobial susceptibility profile of Enterobacterales isolated from Gallus gallus domesticus (commercial laying hens [CLH] and free-range hens [FRH]) in the Caatinga biome. Cloacal swabs were collected from 165 CLH and 165 FRH in the states of Paraíba and Rio Grande do Norte, covered by the Caatinga biome. Bacterial isolation and antimicrobial susceptibility testing were performed, and phenotypic and genotypic detection of extended-spectrum β-lactamases (ESBLs) and cephamycins (AmpC) was carried out, as well as multidrug resistance (MDR) was calculated. Enterobacterales were detected in 92.1% CLH and in 100% FRH. Escherichia coli was the most frequent isolate, followed by Klebsiella spp. CLH showed higher MDR indices (45.4% with MAR ≥ 0.2) and a higher prevalence of resistance genes, including blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, and blaCMY-2. In FRH, MDR was less frequent (18% with MAR ≥ 0.2), but resistance genes were also detected. In Caatinga biome conditions, CLH demonstrated higher frequency of carrying resistant bacteria, reflecting the intensive management of commercial poultry farming. However, FRH, through contact with the environment and other animals, also represent potential reservoirs of MDR Enterobacterales and associated genes.