Abstract

Background/Objectives: Antimicrobial resistance (AMR) in poultry-production environments is an important One Health concern. This phenotypic baseline study investigated the detection and antimicrobial-resistance profiles of Escherichia coli and Salmonella spp. recovered from broiler-farm environmental matrices in the Rabat–Salé–Kénitra region of Morocco. Methods: A cross-sectional field study was conducted in 13 broiler farms on 35 sampling dates between 24 November 2023 and 28 April 2025. A total of 543 samples were collected from poultry manure, drinking troughs, farm soil, soils approximately 200 and 500 m from the poultry houses, and well water. Isolates were identified by culture and API 20E; Salmonella spp. identification was additionally confirmed by real-time PCR. Disk-diffusion results were interpreted using applicable CLSI M100, 31st edition, criteria, and colistin was tested by the colistin broth disk elution MIC method. Multidrug resistance (MDR) was defined as resistance to at least one agent in three or more antimicrobial classes. Results: Escherichia coli and Salmonella spp. were detected in 190/543 (35.0%) and 127/543 (23.4%) samples, respectively. Among E. coli isolates, 115/190 (60.5%) were MDR; the highest matrix-specific proportions occurred in farm soil (85.7%), drinking troughs (83.3%), and poultry manure (75.7%). Among Salmonella spp. isolates, 82/127 (64.6%) were MDR, with the highest proportions in poultry manure (92.9%) and drinking troughs (78.3%). The predominant resistance rates were ampicillin (84.7%), tetracycline (61.6%), and chloramphenicol (55.8%) in E. coli, and nalidixic acid (73.2%), ampicillin (61.4%), and tetracycline (55.9%) in Salmonella spp. Resistant isolates were also detected in surrounding soils and well water; however, the study design did not permit source attribution or inference of transmission direction. Conclusions: Broiler-farm environmental matrices in the study area may represent reservoirs of phenotypically antimicrobial-resistant E. coli and Salmonella spp. The findings provide baseline evidence supporting integrated One Health surveillance, improved biosecurity, manure and litter management, water-system sanitation, and responsible veterinary antimicrobial use. Genomic typing and environmental source-tracking are required to determine persistence and transmission pathways.

IPC Classification

Keywords