Tracking the Prevalence of Antibiotic Resistance in Within the Spanish Poultry Industry: Insights from a One Health Approach.

/: Antimicrobial resistance (AMR) in species from poultry production represents a significant public health threat due to the potential transmission of AMR through the food chain. This study aimed to examine the relative prevalence, resistance patterns, and mannitol fermentation capacity of isolates from various poultry production systems in Spain over a seven-year period (2017-2023). : A total of 215 isolates were analyzed. Phenotypic assessments were conducted to determine resistance rates and metabolic capacities, while genotypic characterization focused on detecting vancomycin-resistance genes (, , , and ). : (62.3%) and (29.77%) were the predominant species, primarily isolated from broilers (74.88%), with the highest frequency observed in one-week-old chicks (31.16%). High resistance rates to tetracyclines and streptogramins were identified, while resistance to vancomycin (0.47%) and tigecycline (3.03%) was low. Interestingly, a significant reduction in tetracyclines resistance was shown in this period for (from 100% to 70% (2017-2023) and (from 100% to 40% (2018-2023)). Multidrug resistance (MDR) was detected in 26.98% of isolates. Mannitol fermentation tests revealed high metabolic capacity in (99.25%) and (96.88%), associated with adaptability and virulence potential. Genotypic analysis showed a very low prevalence of and genes. : These findings highlight the critical need for targeted surveillance and intervention strategies in poultry production to mitigate the risks posed by MDR to public health.