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Animals : an open access journal from MDPI2025; 15(23); 3413; doi: 10.3390/ani15233413

Prevalence and Antimicrobial Resistance Patterns of Salmonella in Asymptomatic Horses in Eastern Spain: A One Health Perspective.

Abstract: are zoonotic pathogens, and rising antimicrobial resistance (AMR) amplifies their public health impact. Asymptomatic horses can act as reservoirs, contributing to environmental contamination and interspecies transmission. This study aimed to estimate the prevalence of and characterize AMR patterns in healthy horses from eastern Spain. Faecal samples from 95 asymptomatic horses were collected once daily over five consecutive days (475 samples in total) and processed under for detection. Epidemiological information was obtained through owner questionnaires, and associations with shedding were analyzed using generalized linear models. Antimicrobial susceptibility was assessed by minimum inhibitory concentration assays following the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. was detected in 25.3% of horses (24/95), with S. Enteritidis, S. Johannesburg, and S. Virchow as the most frequent serotypes. A significant association was observed between proximity of manure storage and bacterial detection ( < 0.001). Among 24 isolates of , 88.9% were resistant to at least one antimicrobial, and 50% exhibited multidrug resistance. The highest resistance rates were against sulfamethoxazole and gentamicin, followed by ciprofloxacin and tigecycline. Healthy horses can act as silent carriers of multidrug-resistant , highlighting the need for surveillance, strengthened biosecurity, and prudent antimicrobial use within a One Health framework.
Publication Date: 2025-11-26 PubMed ID: 41375470PubMed Central: PMC12691379DOI: 10.3390/ani15233413Google Scholar: Lookup
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APA
Simó-Martínez MS, Marco-Fuertes A, Galán-Relaño Á, Astorga Márquez RJ, Marin C, Valero Díaz A, Vega S. (2025). Prevalence and Antimicrobial Resistance Patterns of Salmonella in Asymptomatic Horses in Eastern Spain: A One Health Perspective. Animals (Basel), 15(23), 3413. https://doi.org/10.3390/ani15233413

Publication

ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 15
Issue: 23
PII: 3413

Researcher Affiliations

Simó-Martínez, María Socorro
  • Department of Animal Medicine and Surgery, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Marco-Fuertes, Ana
  • Department of Animal Production and Health, Public Veterinary Health and Food Science and Technology, Faculty of Veterinary Medicine, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Galán-Relaño, Ángela
  • Department of Nursing, Pharmacology and Physiotherapy Area, Faculty of Veterinary Medicine, University of Cordoba, 14014 Cordoba, Spain.
Astorga Márquez, Rafael J
  • Animal Health Department, Veterinary Faculty, University of Cordoba, 14014 Cordoba, Spain.
Marin, Clara
  • Department of Animal Production and Health, Public Veterinary Health and Food Science and Technology, Faculty of Veterinary Medicine, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Valero Díaz, Antonio
  • Food Science and Technology Department, Veterinary Faculty, University of Cordoba, 14014 Cordoba, Spain.
Vega, Santiago
  • Department of Animal Production and Health, Public Veterinary Health and Food Science and Technology, Faculty of Veterinary Medicine, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.

Conflict of Interest Statement

The authors declare no conflicts of interest.

References

This article includes 56 references
  1. Ministerio de Agricultura Pesca y Alimentación G de España. SECTOR EQUINO EN CIFRAS. 2024. [(accessed on 19 November 2025)]. Available online: https://www.mapa.gob.es/dam/mapa/contenido/ganaderia/temas/produccion-y-mercados-ganaderos/sectores-ganaderos-2/equino/informacion-del-sector/indicadores-economicos/indicadores-economicos-equidos-2024.pdf.
  2. Cummings K.J., Perkins G.A., Khatibzadeh S.M., Warnick L.D., Aprea V.A., Altier C. Antimicrobial resistance trends among Salmonella isolates obtained from horses in the northeastern United States (2001–2013) Am. J. Vet Res. 2016;77:505–513. doi: 10.2460/ajvr.77.5.505.
    doi: 10.2460/ajvr.77.5.505pubmed: 27111018google scholar: lookup
  3. Hernandez J.A., Long M.T., Traub-Dargatz J.L., Besser T.E. Equine Infectious Diseases. 2nd ed. Elsevier; Amsterdam, The Netherlands: 2014. Salmonellosis; pp. 321–333.e4.
  4. Dor Z., Shnaiderman-Torban A., Kondratyeva K., Davidovich-Cohen M., Rokney A., Steinman A., Navon-Venezia S. Emergence and Spread of Different ESBL-Producing Salmonella enterica Serovars in Hospitalized Horses Sharing a Highly Transferable IncM2 CTX-M-3-Encoding Plasmid. Front. Microbiol. 2020;11:616032. doi: 10.3389/fmicb.2020.616032.
    doi: 10.3389/fmicb.2020.616032pmc: PMC7773750pubmed: 33391248google scholar: lookup
  5. Barrow P.A., Methner U. Salmonella in Domestic Animals. 2nd ed. CABI; Oxfordshire, UK: 2013. [(accessed on 19 November 2025)]. pp. 305–317. Available online: https://vetbooks.ir/Salmonella-in-domestic-animals-2nd-edition/
  6. European Food Safety Authority (EFSA) European Centre for Disease Prevention and Control (ECDC) The European Union One Health 2023 Zoonoses report. EFSA J. 2024;22:e9106. doi: 10.2903/j.efsa.2024.9106.
    doi: 10.2903/j.efsa.2024.9106pmc: PMC11629028pubmed: 39659847google scholar: lookup
  7. Yellow Book|Yellow Book|CDC. [(accessed on 19 November 2025)];2025 Available online: https://www.cdc.gov/yellow-book/index.html.
  8. Dallap Schaer B.L., Aceto H., Rankin S.C. Outbreak of Salmonellosis Caused by Salmonella enterica Serovar Newport MDR-AmpC in a Large Animal Veterinary Teaching Hospital. J. Vet. Intern. Med. 2010;24:1138–1146. doi: 10.1111/j.1939-1676.2010.0546.x.
  9. Bustos C.P., Dominguez J.E., Garda D., Moroni M., Pallarols Molinari N., Herrera M., Chacana P.A., Mesplet M. Multiresistant and blaCTX-M-14-Carrying Salmonella ser. Typhimurium Isolated During a Salmonellosis Outbreak in an Equine Hospital in Argentina. J. Equine Vet. Sci. 2021;99:103404. doi: 10.1016/j.jevs.2021.103404.
    doi: 10.1016/j.jevs.2021.103404pubmed: 33781422google scholar: lookup
  10. Traub-Dargatz J.L., Salman M.D., Jones R.L. Epidemiologic study of Salmonellae shedding in the feces of horses and potential risk factors for development of the infection in hospitalized horses. J. Am. Vet. Med. Assoc. 1990;196:1617–1622. doi: 10.2460/javma.1990.196.10.1617.
    doi: 10.2460/javma.1990.196.10.1617pubmed: 2347754google scholar: lookup
  11. Dargatz D.A., Traub-Dargatz J.L. Multidrug-resistant Salmonella and nosocomial infections. Vet. Clin. N. Am. Equine Pract. 2004;20:587–600. doi: 10.1016/j.cveq.2004.07.008.
    doi: 10.1016/j.cveq.2004.07.008pubmed: 15519820google scholar: lookup
  12. House J.K., Mainar-Jaime R.C., Smith B.P., House A.M., Kamiya D.Y. Risk factors for nosocomial Salmonella infection among hospitalized horses. J. Am. Vet. Med. Assoc. 1999;214:1511–1516. doi: 10.2460/javma.1999.214.10.1511.
  13. Kim L., Morley P.S., Traub-Dargatz J.L., Salman M.D., Gentry-Weeks C. Factors associated with Salmonella shedding among equine colic patients at a veterinary teaching hospital. J. Am. Vet. Med. Assoc. 2001;218:740–748. doi: 10.2460/javma.2001.218.740.
    doi: 10.2460/javma.2001.218.740pubmed: 11280409google scholar: lookup
  14. Ernst N.S., Hernandez J.A., MacKay R.J., Brown M.P., Gaskin J.M., Nguyen A.D., Giguere S., Colahan P.T., Troedsson M.R., Haines G.R., et al. Risk factors associated with fecal Salmonella shedding among hospitalized horses with signs of gastrointestinal tract disease. J. Am. Vet. Med. Assoc. 2004;225:275–281. doi: 10.2460/javma.2004.225.275.
    doi: 10.2460/javma.2004.225.275pubmed: 15323386google scholar: lookup
  15. Leon I.M., Lawhon S.D., Norman K.N., Threadgill D.S., Ohta N., Vinasco J., Scott H.M. Serotype diversity and antimicrobial resistance among Salmonella enterica isolates from patients at an equine referral hospital. Appl. Environ. Microbiol. 2018;84:e02829-17. doi: 10.1128/AEM.02829-17.
    doi: 10.1128/AEM.02829-17pmc: PMC6007101pubmed: 29678910google scholar: lookup
  16. Wright J.G., Tengelsen L.A., Smith K.E., Bender J.B., Frank R.K., Grendon J.H., Rice D.H., Thiessen A.M.B., Gilbertson C.J., Sivapalasingam S., et al. Multidrug-resistant Salmonella Typhimurium in Four Animal Facilities. Emerg. Infect. Dis. 2005;11:1235–1241. doi: 10.3201/eid1108.050111.
    doi: 10.3201/eid1108.050111pmc: PMC3320505pubmed: 16102313google scholar: lookup
  17. Burgess B.A., Morley P.S. Risk factors for shedding of Salmonella enterica among hospitalized large animals over a 10-year period in a veterinary teaching hospital. J. Vet. Intern. Med. 2019;33:2239–2248. doi: 10.1111/jvim.15579.
    doi: 10.1111/jvim.15579pmc: PMC6766568pubmed: 31410902google scholar: lookup
  18. Astorga R., Arenas A., Tarradas C., Mozos E., Zafra R., Pérez J. Outbreak of peracute septicaemic salmonellosis in horses associated with concurrent Salmonella enteritidis and Mucor species infection. Vet. Rec. 2004;155:240–242. doi: 10.1136/vr.155.8.240.
    doi: 10.1136/vr.155.8.240pubmed: 15384508google scholar: lookup
  19. Bhat K.A., Manzoor T., Dar M.A., Farooq A., Allie K.A., Wani S.M., Dar T.A., Shah A.A. Enterobacteria. IntechOpen; London, UK: 2022. [(accessed on 19 November 2025)]. Salmonella Infection and Pathogenesis. Available online: https://www.intechopen.com/chapters/80044.
  20. Crump J.A., Wain J. Salmonella. Int. Encycl. Public Health. 2017;2:425–433. doi: 10.1016/B978-0-12-803678-5.00394-5.
  21. Burgess B.A. Salmonella in Horses. Vet. Clin. N. Am. Equine Pract. 2023;39:25–35. doi: 10.1016/j.cveq.2022.11.005.
    doi: 10.1016/j.cveq.2022.11.005pubmed: 36737292google scholar: lookup
  22. World Health Organization (WHO) Antimicrobial Resistance. 2024. [(accessed on 19 November 2025)]. Available online: https://www.who.int/news/item/17-05-2024-who-updates-list-of-drug-resistant-bacteria-most-threatening-to-human-health.
  23. Johnson J.A. Nosocomial infections. Vet. Clin. N. Am. Small Anim. Pract. 2002;32:1101–1126. doi: 10.1016/S0195-5616(02)00038-4.
    doi: 10.1016/S0195-5616(02)00038-4pubmed: 12380168google scholar: lookup
  24. Soza-Ossandón P., Rivera D., Tardone R., Riquelme-Neira R., García P., Hamilton-West C., Adell A.D., González-Rocha G., Moreno-Switt A.I. Widespread Environmental Presence of Multidrug-Resistant Salmonella in an Equine Veterinary Hospital That Received Local and International Horses. Front. Vet. Sci. 2020;7:537557. doi: 10.3389/fvets.2020.00346.
    doi: 10.3389/fvets.2020.00346pmc: PMC7366320pubmed: 32754619google scholar: lookup
  25. Mcgowan C. Welfare of Aged Horses. Animals. 2011;1:366–376. doi: 10.3390/ani1040366.
    doi: 10.3390/ani1040366pmc: PMC4513472pubmed: 26486621google scholar: lookup
  26. Gómez-Arrones Egido V. Cuidados del Caballo Geriátrico. 2023. [(accessed on 19 November 2025)]. Available online: https://www.diarioveterinario.com/t/4290842/cuidados-caballo-geriatrico-equino#:~:text=Hoy%20en%20d%C3%ADa%20se%20considera,o%20senior%20m%C3%A1s%20de%2020.
  27. Plana M., Farriols M.M. El Potro y las Etapas de su Desarrollo. 2020. [(accessed on 19 November 2025)]. Available online: https://www.ecuestre.es/app/blogs/doma-educativa-y-equitacion-conectada/el-potro-y-las-etapas-de-su-desarrollo.
  28. Lowther A. Skeletal Maturity in Horses: Growth Plate Ossification and Age Considerations. 2023. [(accessed on 19 November 2025)]. Available online: https://www.horsesinsideout.com/post/skeletal-maturity-in-horses-growth-plate-ossification-and-age-considerations.
  29. Microbiology of the Food Chain—Horizontal Method for the Detection, Enumeration and Serotyping of Salmonella—Part 1: Detection of Salmonella spp. ISO; Geneva, Switzerland: 2017.
    pubmed: 29803313
  30. Grimont P.A.D., Weill F.X. Antigenic Formulae of the Salmonella serovars. 9th ed. WHO; Geneva, Switzerland: 2007. WHO Collaborating Centre for Reference and Research on Salmonella.
  31. European Food Safety Authority (EFSA) European Centre for Disease Prevention and Control (ECDC) The European Union Summary Report on Antimicrobial Resistance in zoonotic and indicator bacteria from humans, animals and food in 2020/2021. EFSA J. 2023;21:e07867. doi: 10.2903/j.efsa.2023.7867.
    doi: 10.2903/j.efsa.2023.7867pmc: PMC9987209pubmed: 36891283google scholar: lookup
  32. The European Committee on Antimicrobial Susceptibility Testing Breakpoint Tables for Interpretation of MICs and Zone Diameters. 2025. [(accessed on 19 November 2025)]. Version 15.0. Available online: https://www.eucast.org/fileadmin/src/media/PDFs/EUCAST_files/Breakpoint_tables/v_15.0_Breakpoint_Tables.pdf.
  33. Magiorakos A.P., Srinivasan A., Carey R.B., Carmeli Y., Falagas M.E., Giske C.G., Harbarth S., Hindler J.F., Kahlmeter G., Olsson-Liljequist B., et al. Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: An international expert proposal for interim standard definitions for acquired resistance. Clin. Microbiol. Infect. 2012;18:268–281. doi: 10.1111/j.1469-0691.2011.03570.x.
  34. Pichner R., Sander A., Steinrück H., Gareis M. Occurrence of Salmonella spp. and shigatoxin-producing Escherichia coli (STEC) in horse faeces and horse meat products. Berl. Munch. Tierarztl. Wochenschr. 2005;118:321–325.
    pubmed: 16048044
  35. Traub-Dargatz J.L., Garber L.P., Fedorka-Cray P.J., Ladely S., Ferris K.E. Fecal shedding of Salmonella spp. by horses in the United States during 1998 and 1999 and detection of Salmonella spp. in grain and concentrate sources on equine operations. J. Am. Vet. Med. Assoc. 2000;217:226–230. doi: 10.2460/javma.2000.217.226.
    doi: 10.2460/javma.2000.217.226pubmed: 10909464google scholar: lookup
  36. Alinovi C.A., Ward M.P., Couëtil L.L., Wu C.C. Risk factors for fecal shedding of Salmonella from horses in a veterinary teaching hospital. Prev. Vet. Med. 2003;60:307–317. doi: 10.1016/S0167-5877(03)00143-0.
    doi: 10.1016/S0167-5877(03)00143-0pubmed: 12941555google scholar: lookup
  37. Uzal F.A., Arroyo L.G., Navarro M.A., Gomez D.E., Asín J., Henderson E. Bacterial and viral enterocolitis in horses: A review. J. Vet. Diagn. Investig. 2022;34:354–375. doi: 10.1177/10406387211057469.
    doi: 10.1177/10406387211057469pmc: PMC9254067pubmed: 34763560google scholar: lookup
  38. Smith B.P., Reina-Guerra M., Hardy A.J. Prevalence and epizootiology of equine salmonellosis. J. Am. Vet. Med. Assoc. 1978;172:353–356. doi: 10.2460/javma.1978.172.03.353.
    doi: 10.2460/javma.1978.172.03.353pubmed: 340435google scholar: lookup
  39. Pusterla N., Byrne B.A., Hodzic E., Mapes S., Jang S.S., Magdesian K.G. Use of quantitative real-time PCR for the detection of Salmonella spp. in fecal samples from horses at a veterinary teaching hospital. Vet. J. 2010;186:252–255. doi: 10.1016/j.tvjl.2009.08.022.
    doi: 10.1016/j.tvjl.2009.08.022pubmed: 19766027google scholar: lookup
  40. Roberts M.C., O’boyle D.A. The prevalence and epizootiology of salmonellosis among groups of horses in south east Queensland. Aust. Vet. J. 1981;57:27–35. doi: 10.1111/j.1751-0813.1981.tb07081.x.
  41. Funk J.A., Davies P.R., Nichols M.A. The Effect of Fecal Sample Weight on Detection of Salmonella enterica in Swine Feces. J. Vet. Diagn. Investig. 2000;12:412–418. doi: 10.1177/104063870001200504.
    doi: 10.1177/104063870001200504pubmed: 11021427google scholar: lookup
  42. Burgess B.A., Morley P.S. Managing Salmonella in Equine Populations. Vet. Clin. N. Am. Equine Pract. 2014;30:623–640. doi: 10.1016/j.cveq.2014.08.005.
    doi: 10.1016/j.cveq.2014.08.005pubmed: 25282320google scholar: lookup
  43. Owen R.A., Fullerton J., Barnum D.A. Effects of transportation, surgery, and antibiotic therapy in ponies infected with Salmonella. Am. J. Vet. Res. 1983;44:46–50. doi: 10.2460/ajvr.1983.44.01.46.
    doi: 10.2460/ajvr.1983.44.01.46pubmed: 6337537google scholar: lookup
  44. Hird D.W., Casebolt D.B., Carter J.D., Pappaioanou M., Hjerpe C.A. Risk factors for salmonellosis in hospitalized horses. J. Am. Vet. Med. Assoc. 1986;188:173–177. doi: 10.2460/javma.1986.188.02.173.
    doi: 10.2460/javma.1986.188.02.173pubmed: 3700214google scholar: lookup
  45. Bernard W.V., Sebastian M., Hemming B. Salmonella Antimicrobial Activity of Selected Strains of Enterolactobacillus Species Isolated from the Gastrointestinal Tract of the Horse. J. Equine Vet. Sci. 2011;31:396–399. doi: 10.1016/j.jevs.2011.03.016.
  46. Hermosilla J., Joan P., Membrado-Tena C., Aparicio J.V., Fansa G., Antequera M. Estudios Comarcales de la Provincia de Valencia/Estudis Comarcals de la Província de València. Dirección y Coordinación Técnica/Direcció i Coordinació Tècnica Equipo Técnico/Equip Tècnic: ESTEPA Cartografía/Cartografia. 2018. [(accessed on 19 November 2025)]. Available online: https://datos.divaladl.es/userfiles/1078/Documentos/930e90368dEC_bunyol_OK.pdf.
  47. National Oceanic and Atmospheric Administration (NOAA) Climate change impacts|National Oceanic and Atmospheric Administration. [(accessed on 19 November 2025)];2025 Available online: https://www.noaa.gov/education/resource-collections/climate/climate-change-impacts.
  48. Brenner F.W., Villar R.G., Angulo F.J., Tauxe R., Swaminathan B. Salmonella Nomenclature. J. Clin. Microbiol. 2000;38:2465–2467. doi: 10.1128/JCM.38.7.2465-2467.2000.
  49. Pulford C.V., Wenner N., Redway M.L., Rodwell E.V., Webster H.J., Escudero R., Kröger C., Canals R., Rowe W., Lopez J., et al. The diversity, evolution and ecology of Salmonella in venomous snakes. PLoS Negl. Trop. Dis. 2019;13:e0007169. doi: 10.1371/journal.pntd.0007169.
  50. Mlangeni L.N., Ramatla T., Lekota K.E., Price C., Thekisoe O., Weldon C. Occurrence, Antimicrobial Resistance, and Virulence Profiles of Salmonella Serovars Isolated from Wild Reptiles in South Africa. Int. J. Microbiol. 2024;2024:5213895. doi: 10.1155/2024/5213895.
    doi: 10.1155/2024/5213895pmc: PMC10787053pubmed: 38222969google scholar: lookup
  51. Santana-Hernández K.M., Rodríguez-Ponce E., Medina I.R., Acosta-Hernández B., Priestnall S.L., Vega S., Marin C., Cerdà-Cuéllar M., Marco-Fuertes A., Ayats T., et al. One Health Approach: Invasive California Kingsnake (Lampropeltis californiae) as an Important Source of Antimicrobial Drug-Resistant Salmonella Clones on Gran Canaria Island. Animals. 2023;13:1790. doi: 10.3390/ani13111790.
    doi: 10.3390/ani13111790pmc: PMC10251910pubmed: 37889724google scholar: lookup
  52. Kaspar U., von Lützau K., Schlattmann A., Rösler U., Köck R., Becker K. Zoonotic multidrug-resistant microorganisms among non-hospitalized horses from Germany. One Health. 2019;7:100091. doi: 10.1016/j.onehlt.2019.100091.
  53. Kohnen A.B., Wiedenheft A.M., Traub-Dargatz J.L., Short D.M., Cook K.L., Lantz K., Morningstar-Shaw B., Lawrence J.P., House S., Marshall K.L., et al. Antimicrobial susceptibility of Salmonella and Escherichia coli from equids sampled in the NAHMS 2015–16 equine study and association of management factors with resistance. Prev. Vet. Med. 2023;213:105857. doi: 10.1016/j.prevetmed.2023.105857.
  54. Chipangura J.K., Chetty T., Kgoete M., Naidoo V. Prevalence of antimicrobial resistance from bacterial culture and susceptibility records from horse samples in South Africa. Prev. Vet. Med. 2017;148:37–43. doi: 10.1016/j.prevetmed.2017.10.004.
  55. Haq I., Durrani A.Z., Khan M.S., Mushtaq M.H., Ahmad I. Study of antimicrobial resistance and physiological biomarkers with special reference to Salmonellosis in diarrheic foals in Punjab, Pakistan. Acta Trop. 2017;176:144–149. doi: 10.1016/j.actatropica.2017.08.003.
  56. Feary D.J., Hassel D.M. Enteritis and Colitis in Horses. Vet. Clin. N. Am. Equine Pract. 2006;22:437–479. doi: 10.1016/j.cveq.2006.03.008.
    doi: 10.1016/j.cveq.2006.03.008pubmed: 16882483google scholar: lookup

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