Seasonal runoff-driven transport of oxytetracycline from swine feces and its effects on soil bacteria and antimicrobial resistance risk
4 affiliations
- 1Laboratorio de Toxicología, Departamento de Fisiopatología, CIVETAN, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Tandil, Buenos Aires, Argentina
- 2Departamento de Producción Animal, Facultad de Ciencias Veterinarias, UNCPBA, Tandil, Buenos Aires, Argentina
- 3Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- 4Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CICPBA), La Plata, Buenos Aires, Argentina
Abstract
Inroduction: The environmental dissemination of veterinary antibiotics through livestock feces represents a relevant concern within the One Health framework due to its potential effects on ecosystem functioning and antimicrobial resistance (AMR) selection. Oxytetracycline (OTC), widely used in swine production systems, is excreted largely as parent compound and may reach surrounding environments through rainfall-driven runoff. This study evaluated the seasonal persistence and runoff-mediated transport of OTC from swine feces under natural field conditions.
Methods: Experimental fecal deposits fortified with OTC were exposed outdoors for 30 days across four seasons, and runoff water generated after natural precipitation events was collected and analyzed by HPLC-UV. In parallel, culturable aerobic mesophilic bacteria were quantified in exposed soils to assess potential microbiological responses. Meteorological variables were integrated to evaluate their influence on OTC mobilization and environmental behavior.
Results and discussion: OTC residues were detected in runoff water in all seasons and persisted until late-stage rainfall events, indicating sustained environmental availability and continuous hydrological transport. Higher concentrations were generally associated with increased precipitation intensity and erosivity, whereas cumulative precipitation and temperature emerged as key explanatory variables in regression models. Sediment production followed similar seasonal patterns, highlighting the potential relevance of particle-associated transport pathways that warrant further quantitative investigation. OTC-exposed soils showed significantly higher culturable bacterial counts than controls, indicating shifts in microbial abundance under antibiotic exposure, which potentially reflects the selection of tolerant bacterial populations. Importantly, all detected concentrations exceeded the predicted no-effect concentration for resistance selection (PNECMIC), resulting in consistently high risk quotients across all seasons, and indicating a high potential risk for resistance selection. These findings demonstrate that runoff represents a relevant pathway for the environmental dissemination of OTC from swine feces under realistic field conditions. The persistence of residues and the consistently high AMR selection risk highlight the need to integrate environmental monitoring and resistance risk assessment into livestock waste management strategies.
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BibTeX
@article{mozo2026seasonal,
title = {{Seasonal runoff-driven transport of oxytetracycline from swine feces and its effects on soil bacteria and antimicrobial resistance risk}},
author = {Joaquín Mozo and Julieta María Decundo and Guadalupe Martínez and Susana Nelly Dieguez and Alejandro Luis Soraci and Denisa Soledad Pérez Gaudio},
journal = {Frontiers in Veterinary Science},
year = {2026},
month = oct,
doi = {10.3389/fvets.2026.1919739},
url = {https://doi.org/10.3389/fvets.2026.1919739},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Seasonal runoff-driven transport of oxytetracycline from swine feces and its effects on soil bacteria and antimicrobial resistance risk
AU - Joaquín Mozo
AU - Julieta María Decundo
AU - Guadalupe Martínez
AU - Susana Nelly Dieguez
AU - Alejandro Luis Soraci
AU - Denisa Soledad Pérez Gaudio
PY - 2026
DA - 2026/10/12
JO - Frontiers in Veterinary Science
DO - 10.3389/fvets.2026.1919739
UR - https://doi.org/10.3389/fvets.2026.1919739
AB - Inroduction: The environmental dissemination of veterinary antibiotics through livestock feces represents a relevant concern within the One Health framework due to its potential effects on ecosystem functioning and antimicrobial resistance (AMR) selection. Oxytetracycline (OTC), widely used in swine production systems, is excreted largely as parent compound and may reach surrounding environments through rainfall-driven runoff. This study evaluated the seasonal persistence and runoff-mediated transport of OTC from swine feces under natural field conditions. Methods: Experimental fecal deposits fortified with OTC were exposed outdoors for 30 days across four seasons, and runoff water generated after natural precipitation events was collected and analyzed by HPLC-UV. In parallel, culturable aerobic mesophilic bacteria were quantified in exposed soils to assess potential microbiological responses. Meteorological variables were integrated to evaluate their influence on OTC mobilization and environmental behavior. Results and discussion: OTC residues were detected in runoff water in all seasons and persisted until late-stage rainfall events, indicating sustained environmental availability and continuous hydrological transport. Higher concentrations were generally associated with increased precipitation intensity and erosivity, whereas cumulative precipitation and temperature emerged as key explanatory variables in regression models. Sediment production followed similar seasonal patterns, highlighting the potential relevance of particle-associated transport pathways that warrant further quantitative investigation. OTC-exposed soils showed significantly higher culturable bacterial counts than controls, indicating shifts in microbial abundance under antibiotic exposure, which potentially reflects the selection of tolerant bacterial populations. Importantly, all detected concentrations exceeded the predicted no-effect concentration for resistance selection (PNECMIC), resulting in consistently high risk quotients across all seasons, and indicating a high potential risk for resistance selection. These findings demonstrate that runoff represents a relevant pathway for the environmental dissemination of OTC from swine feces under realistic field conditions. The persistence of residues and the consistently high AMR selection risk highlight the need to integrate environmental monitoring and resistance risk assessment into livestock waste management strategies.
SN - 2297-1769
ER -