Abstract
<jats:p>Antimicrobial resistance (AMR) is increasingly recognized in wildlife, reflecting environmental exposure to antimicrobial agents. Among wild carnivores, red foxes (Vulpes vulpes) are considered useful sentinels for monitoring environmental dissemination of resistant bacteria. Escherichia coli and Proteus mirabilis are common intestinal commensals that can acquire and transfer resistance determinants. In Romania, oxytetracycline is included as a biomarker in oral anti-rabies vaccine baits distributed to fox populations, potentially contributing to the selection of resistant bacteria in these animals. This study aimed to evaluate the phenotypic resistance to tetracycline in E. coli and P. mirabilis isolates recovered from wild red foxes in Romania and to assess the potential influence of environmental exposure to tetracyclines from anti-rabies vaccination baits. Thirty bacterial isolates, including twenty E. coli, respectively ten P. mirabilis strains, previously identified using the Vitek 2 Compact system were examined for tetracycline susceptibility using the Kirby-Bauer disk diffusion method, according to standard interpretative criteria. Among the E. coli isolates, 11 (55%) were resistant to tetracycline, while 9 (45%) were susceptible. All P. mirabilis isolates (100%) exhibited resistance to tetracycline. These findings confirm the presence of tetracycline-resistant phenotypes among enteric bacteria from wild red foxes. The detection of tetracycline-resistant E. coli and P. mirabilis in wild red foxes may reflect both intrinsic and environmentally influenced resistance, possibly linked to oxytetracycline exposure from vaccination baits. Ongoing antimicrobial resistance monitoring in wildlife supports the One Health approach to understanding environmental antimicrobial dissemination.</jats:p>