Comparative Antimicrobial Resistance Patterns in Extraintestinal Escherichia coli Isolates from Humans and Broiler Chickens in the Meknes Region, Morocco: A One Health Study

Background/Objectives: Antimicrobial resistance (AMR) is a major One Health challenge affecting both human and animal health. Comparative studies investigating resistance patterns across reservoirs remain limited in Morocco. This study compared antimicrobial resistance profiles and presumptive β-lactam resistance phenotypes of extraintestinal Escherichia coli isolates from humans and broiler chickens. Methods: A comparative cross-sectional study was conducted using 874 non-duplicate human-derived E. coli isolates and 142 broiler-derived E. coli isolates. Antimicrobial susceptibility testing was performed using the disk diffusion method according to CA-SFM/EUCAST 2024 guidelines. Resistance rates and presumptive β-lactam resistance phenotypes were compared between reservoirs. Results: Broiler isolates exhibited significantly higher resistance to amoxicillin (93.0% vs. 65.5%), ticarcillin (92.9% vs. 64.1%), amoxicillin–clavulanic acid (75.2% vs. 48.1%), fluoroquinolones, trimethoprim–sulfamethoxazole, fosfomycin, and gentamicin (all p < 0.05). In contrast, resistance to cephalosporins was significantly higher among human isolates, whereas resistance to cefoxitin and carbapenems was detected exclusively among human isolates. The presumptive IRT-like phenotype was markedly more prevalent in broiler isolates (66.9% vs. 26.9%; OR = 5.50; p < 0.001), while the presumptive AmpC and carbapenem-resistant phenotypes were identified only in human isolates. Conversely, the wild-type phenotype was significantly more frequent among human isolates (33.1% vs. 5.6%; OR = 0.12; p < 0.001). The prevalence of the presumptive ESBL phenotype was comparable between reservoirs (12.1% vs. 8.5%; p = 0.258). Conclusions: Human-derived and broiler-derived E. coli isolates exhibited distinct antimicrobial resistance patterns and β-lactam resistance profiles. Resistance levels were significantly higher among broiler isolates for most antimicrobial agents tested, whereas resistance to cephalosporins was significantly higher among human isolates, with cefoxitin and carbapenem resistance detected exclusively in the latter. Human isolates displayed a greater diversity of presumptive β-lactam resistance phenotypes, whereas broiler isolates were largely dominated by the presumptive IRT-like phenotype. The detection of isolates with a presumptive ESBL phenotype among broilers despite the absence of documented routine use of extended-spectrum cephalosporins highlights the potential contribution of horizontal gene transfer and co-selection. Further molecular and antimicrobial consumption studies are warranted to clarify the drivers of resistance dissemination within a One Health framework.