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

Authors

Katianny Bezerra de Medeiros, Ana Beatriz Monteiro de Medeiros, Débora Luise Canuto de Sousa, José Diniz de Souto Sobrinho, Tiago Casella, Carolina Sousa Américo Batista de Santos, Sérgio Santos de Azevedo

Published in

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology]. Volume 57. Issue 1. Jul 01, 2026. Epub Jul 01, 2026.

Abstract

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 bla_CTX-M-1, bla_CTX-M-2, bla_CTX-M-8, and bla_CMY-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.

PMID:
42384248
Bibliographic data and abstract were imported from PubMed on 01 Jul 2026.

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