Antimicrobial resistance (AMR) is an increasing concern under the One Health framework. Extensive antibiotic use in livestock production may impose selective pressure, suppressing susceptible bacteria while allowing bacteria carrying antimicrobial resistance genes (ARGs) to survive and proliferate, thereby enriching ARGs and making livestock farms potential reservoirs. When carried by pathogens, ARGs may reduce antibiotic effectiveness and lead to treatment failure. This seminar introduces two studies investigating airborne dissemination of livestock-associated ARGs and evaluating whether farm-level interventions can reduce their abundance.In the first study, airborne dissemination was investigated across swine, cattle, layer, and broiler farms using droplet digital PCR (ddPCR) and 16S rRNA gene sequencing. Airborne ARG concentrations ranged from approximately 10² to 10⁴ copies/m³, with some ARGs and mobile genetic elements (MGEs) showing enrichment relative to feces. Disturbance of fecal material can aerosolize particles carrying bacteria and ARGs. Once airborne, differences in tolerance to desiccation and nutrient limitation may favor better-adapted ARG-carrying bacteria, contributing to ARG enrichment. ARGs and MGEs showed stronger associations in air than in feces, indicating greater ARG–MGE co-occurrence. MGEs can carry ARGs or facilitate their movement between bacterial hosts through horizontal gene transfer (HGT). Through HGT, ARGs may be transferred from one bacterium to another. If the transferred ARGs are successfully expressed, the receiving bacterium may become resistant to antibiotics. The inhalation assessment also indicated potential farmworker exposure to antimicrobial-resistant bacteria and ARGs.In the second study, best farming practices were evaluated across ten dairy farms. These included prudent antimicrobial use, selective therapy, improved hygiene, and immunoprophylactic measures. Although total antimicrobial prescriptions did not differ significantly between the two sampling periods, the total ARG abundance decreased significantly from 2020 to 2022, with reductions also observed in specific ARGs associated with β-lactam and tetracycline resistance. These findings suggest that targeted farm management and hygiene improvements may help reduce ARG burdens even without a significant reduction in overall antimicrobial prescriptions.Collectively, these findings indicate that livestock farms can serve as ARG reservoirs with potential airborne dissemination and farmworker exposure, while targeted management can reduce ARG abundance at the source. Under the One Health framework, AMR control should integrate prudent antimicrobial use, disease prevention, farm management, and continued monitoring across the animal–environment–human interface.
- Xin, H., M. Gao, X. Wang, T. Qiu, Y. Guo, and L. Zhang. 2022. Animal farms are hot spots for airborne antimicrobial resistance. Sci. Total Environ. 851:158050.
- Salerno, B., M. Cornaggia, R. Sabatino, A. Di Cesare, C. Mantovani, L. Barco, B. Cordioli, L. Bano, and C. Losasso. 2025. The “best practices for farming” successfully contributed to decrease the antibiotic resistance gene abundances within dairy farms. Front. Vet. Sci. 11:1420282.
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