FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Antibiotics (Basel, Switzerland)2025; 14(10); 1037; doi: 10.3390/antibiotics14101037

Analysis of Staphylococcal Diversity in the Skin Microbiota of Healthy Riding Horses.

Abstract: In animals, staphylococci constitute a significant part of the normal skin microbiota and mucous membranes. There is limited information available on staphylococci isolated from healthy horses. These skin-associated bacteria can be easily transferred between animals and horse riders via direct contact. Patients undergoing hippotherapy (i.e., medical or therapeutic sessions with horses) are especially at risk of being colonized by horse skin-associated bacteria. However, it remains unclear whether equine skin is colonized by antimicrobial-resistant (AMR) opportunistic pathogens, which may be of concern to human health. We cultivate staphylococci from samples collected from healthy, non-vet-visiting horses who live on private farms in a rural area. In total, 61 strains were isolated and identified at the species level using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The diversity of species in the equine skin microbiota was relatively high and, with the exception of , all the other recovered strains were coagulase-negative staphylococci (CoNS). In total, eleven different staphylococcal species were identified: , , , , , , , , , , and . These results indicate that healthy equine skin is colonized by opportunistic pathogens that can be causative agents of infections that are also severe in humans. The resistance among the isolated strains was observed in eight antimicrobials of the total tested and 36% (22/61) of the isolates were resistant to at least one antimicrobial. However, their resistance to critically important antibiotics used in human medicine was low. Seven isolates (11.5%; 7/61) were classified as multidrug-resistant (MDR). (1/61) showed MDR and was methicillin-resistant. The isolate contained genes conferring resistance to antibiotics, i.e., β-lactams (, ), aminoglycosides ((')/(″)), and macrolide-lincosamide-streptogramin B ((), (), and (/)). Also CoNS harbored genes conferring resistance to β-lactams (), aminoglycosides ((')/(″), (')), MLSB ((), (), (/)), and tetracycline (, ).
Get Full Text
Publication Date: 2025-10-16 PubMed ID: 41148728PubMed Central: PMC12561800DOI: 10.3390/antibiotics14101037Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study investigated the types and antibiotic resistance of staphylococcal bacteria found on the skin of healthy riding horses.
  • The goal was to understand the diversity of these bacteria and assess potential risks for humans, particularly those in close contact such as horse riders and patients undergoing hippotherapy.

Background

  • Staphylococci are common bacteria that normally live on the skin and mucous membranes of animals, including horses.
  • There is limited information about the specific staphylococcal species present on healthy horses and their antibiotic resistance profiles.
  • Close contact between horses and humans can facilitate transfer of these bacteria, posing possible infection risks.
  • Hippotherapy patients, who have therapeutic sessions involving horses, are especially vulnerable to colonization by horse-associated bacteria.
  • A concern exists that horse skin might harbor antimicrobial-resistant (AMR) opportunistic pathogens harmful to human health.

Research Methods

  • Samples were collected from healthy horses living in rural private farms, none of which had recent veterinary visits, to represent natural skin bacterial communities.
  • Staphylococcal strains were cultivated from these samples and identified at the species level using MALDI-TOF MS, a precise mass spectrometry technique.
  • A total of 61 staphylococcal strains were isolated from the skin of these horses.

Results: Species Diversity

  • The study found a high diversity of staphylococcal species on equine skin.
  • Except for one species, all isolated strains were coagulase-negative staphylococci (CoNS), which usually are less aggressive but important opportunistic pathogens.
  • Eleven different staphylococcal species were identified, demonstrating rich bacterial variation on healthy horse skin.
  • These opportunistic pathogens on horse skin have the potential to cause infections in humans as well.

Results: Antibiotic Resistance

  • Antimicrobial resistance was observed in 36% (22 out of 61) of the isolated strains to at least one tested antibiotic.
  • Resistance appeared against eight different kinds of antibiotics.
  • Despite this, resistance to critically important antibiotics for humans was low, which is a positive finding.
  • Seven isolates (11.5%) were multidrug-resistant (MDR), meaning resistant to multiple antibiotic classes.
  • One isolate was both MDR and methicillin-resistant, highlighting a notable threat due to difficulty treating such infections.

Genetic Mechanisms of Resistance

  • The methicillin-resistant isolate contained genes that confer resistance to multiple antibiotic classes:
    • β-lactams – including genes mecA, blaZ
    • Aminoglycosides – genes like aac(6′)/aph(2”)
    • Macrolide-lincosamide-streptogramin B (MLSB) – genes erm(A), erm(C), mph(C)/msr(A)
  • Coagulase-negative staphylococci (CoNS) also harbored resistance genes to:
    • β-lactams (blaZ)
    • Aminoglycosides (aac(6′)/aph(2”), aph(3′))
    • MLSB antibiotics (erm(A), erm(C), mph(C)/msr(A))
    • Tetracycline (tet(K), tet(M))

Implications

  • Healthy riding horses carry a diverse population of staphylococci, including opportunistic pathogens that could affect humans.
  • The presence of antibiotic-resistant and multidrug-resistant bacteria on horse skin poses a potential health risk, especially to individuals in close contact with horses.
  • Low resistance to critical human antibiotics is reassuring but ongoing surveillance is important.
  • The findings highlight the need for proper hygiene and possibly monitoring microbial transfer during hippotherapy or other close-contact activities involving horses.

Cite This Article

APA
Wesołowska M, Szczuka E. (2025). Analysis of Staphylococcal Diversity in the Skin Microbiota of Healthy Riding Horses. Antibiotics (Basel), 14(10), 1037. https://doi.org/10.3390/antibiotics14101037

Publication

Antibiotics (Basel, Switzerland)
ISSN: 2079-6382
NlmUniqueID: 101637404
Country: Switzerland
Language: English
Volume: 14
Issue: 10
PII: 1037

Researcher Affiliations

Wesołowska, Maria
  • Department of Microbiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland.
Szczuka, Ewa
  • Department of Microbiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland.

Conflict of Interest Statement

The authors declare no conflict of interest.

References

This article includes 49 references
  1. Lönker N.S., Fechner K., Wahed A.A.E.. Horses as a crucial part of One Health.. Vet. Sci. 2020;7:28.
    doi: 10.3390/vetsci7010028pmc: PMC7157506pubmed: 32121327google scholar: lookup
  2. Khairullah A.R., Sudjarwo S.A., Effendi M.H., Ramandinianto S.C., Widodo A., Riwu K.H.P.. A review of horses as a source of spreading livestock-associated methicillin-resistant Staphylococcus aureus to human health.. Vet. World. 2022;15:1906–1915.
    doi: 10.14202/vetworld.2022.1906-1915pmc: PMC9615495pubmed: 36313842google scholar: lookup
  3. Cosseau C., Romano-Bertrand S., Duplan H., Lucas O., Ingrassia I., Pigasse C., Roques C., Jumas-Bilakb E.. Proteobacteria from the human skin microbiota: Species-level diversity and hypotheses.. One Health. 2016;2:33–41.
    doi: 10.1016/j.onehlt.2016.02.002pmc: PMC5441325pubmed: 28616476google scholar: lookup
  4. Marshall K., Marsella R.. Evolution of the prevalence of antibiotic resistance to Staphylococcus spp. isolated from horses in Florida over a 10-year period.. Vet. Sci. 2023;10:71.
    doi: 10.3390/vetsci10020071pmc: PMC9959586pubmed: 36851375google scholar: lookup
  5. Sauvé F.. Staphylococcal cutaneous infection in horses: From the early 2000s to the present.. Can. Vet. J. 2021;62:1001–1006.
    pmc: PMC8360305pubmed: 34475588
  6. Kaiser-Thom S., Gerber V., Collaud A., Hurni J., Perreten V.. Prevalence and WGS-based characteristics of Staphylococcus aureus in the nasal mucosa and pastern of horses with equine pastern dermatitis.. BMC Vet. Res. 2022;18:79.
    doi: 10.1186/s12917-021-03053-ypmc: PMC8867626pubmed: 35209904google scholar: lookup
  7. Kaspar U., 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.2019.100091pmc: PMC6468158pubmed: 31016221google scholar: lookup
  8. White S.D.. Equine bacterial and fungal diseases: A diagnostic and therapeutic update.. Clin. Tech. Equine Pract. 2005;4:302–310.
    doi: 10.1053/j.ctep.2005.10.004google scholar: lookup
  9. Beims H., Overmann A., Fulde M., Steinert M., Bergmann S.. Isolation of Staphylococcus sciuri from horse skin infection.. Open Vet. J. 2016;6:242–246.
    doi: 10.4314/ovj.v6i3.14pmc: PMC5223282pubmed: 28116248google scholar: lookup
  10. Westgate S.J., Percival S.L., Knottenbelt D.C., Clegg P.D., Cochrane C.A.. Microbiology of equine wounds and evidence of bacterial biofilms.. Vet. Microbiol. 2011;150:152–159.
    doi: 10.1016/j.vetmic.2011.01.003pubmed: 21273008google scholar: lookup
  11. Kamus L.J., Theoret C., Costa M.C.. Use of next generation sequencing to investigate the microbiota of experimentally induced wounds and the effect of bandaging in horses.. PLoS ONE. 2018;13:e0206989.
    doi: 10.1371/journal.pone.0206989pmc: PMC6261015pubmed: 30475922google scholar: lookup
  12. Schwarz S., Feßler A.T., Loncaric I., Wu C., Kadlec K., Wang Y., Shen J.. Antimicrobial resistance among staphylococci of animal origin.. Microbiol. Spectr. 2018;6:ARBA-0010-2017.
    doi: 10.1128/microbiolspec.ARBA-0010-2017pmc: PMC11633598pubmed: 29992898google scholar: lookup
  13. Isgren C.M.. Improving clinical outcomes via responsible antimicrobial use in horses.. Equine Vet. Educ. 2022;34:482–492.
    doi: 10.1111/eve.13502google scholar: lookup
  14. Aires-de-Sousa M.. Methicillin-resistant Staphylococcus aureus among animals: Current overview.. Clin. Microbiol. Infect. 2017;23:373–380.
    doi: 10.1016/j.cmi.2016.11.002pubmed: 27851997google scholar: lookup
  15. Madhaiyan M., Wirth J.S., Saravanan V.S.. Phylogenomic analyses of the Staphylococcaceae family suggest the reclassification of five species within the genus Staphylococcus as heterotypic synonyms, the promotion of five subspecies to novel species, the taxonomic reassignment of five Staphylococcus species to Mammaliicoccus gen. nov., and the formal assignment of Nosocomiicoccus to the family Staphylococcaceae.. Int. J. Syst. Evol. Microbiol. 2020;70:5926–5936.
    doi: 10.1099/ijsem.0.004498pubmed: 33052802google scholar: lookup
  16. Matsuo E, Kawano J, Yasuda R, Takagi M, Shimizu A, Anzai T, Hashikura S. Species distribution of Staphylococci in the nares and skin of horses.. J. Equine Sci. 2001;12:127–134.
    doi: 10.1294/jes.12.127google scholar: lookup
  17. Schnellmann C, Gerber V, Rossano A, Jaquier V, Panchaud Y, Doherr M.G, Thomann A, Straub R, Perreten V. Presence of new mecA and mph(C) variants conferring antibiotic resistance in Staphylococcus spp. isolated from the skin of horses before and after clinic admission.. J. Clin. Microbiol. 2006;44:4444–4454.
    doi: 10.1128/JCM.00868-06pmc: PMC1698435pubmed: 17005735google scholar: lookup
  18. Uchida-Fujii E, Niwa H, Kanai K, Kinoshita Y, Kuroda T, Toshio Nukada T, Takanori Ueno T. Outbreak of methicillin-resistant Staphylococcus aureus sequence type 1, spa type t1784, in an equine hospital in Japan.. Vet. Anim. Sci. 2022;17:100259.
    doi: 10.1016/j.vas.2022.100259pmc: PMC9253831pubmed: 35800153google scholar: lookup
  19. Ahmad-Mansour N, Loubet P, Pouget C, Dunyach-Remy C, Sotto A, Lavigne J.P, Molle V. Staphylococcus aureus toxins: An update on their pathogenic properties and potential treatments.. Toxins 2021;13:677.
    doi: 10.3390/toxins13100677pmc: PMC8540901pubmed: 34678970google scholar: lookup
  20. Swaney M.H, Kalan L.R. Living in your skin: Microbes, molecules, and mechanisms.. Infect. Immun. 2021;89:e00695-20.
    doi: 10.1128/IAI.00695-20pmc: PMC8090955pubmed: 33468585google scholar: lookup
  21. Shittu A, Lin J, Morrison D, Kolawole D. Isolation and molecular characterization of multiresistant Staphylococcus sciuri and Staphylococcus haemolyticus associated with skin and soft-tissue infections.. J. Med. Microbiol. 2004;53:51–55.
    doi: 10.1099/jmm.0.05294-0pubmed: 14663105google scholar: lookup
  22. Stepanovic S, Dakic I, Morrison D, Hauschild T, Jezek P, Petrás P, Martel A, Vukovic D, Shittu A, Devriese L.A. Identification and characterization of clinical isolates of members of the Staphylococcus sciuri group.. J. Clin. Microbiol. 2005;43:956–958.
    doi: 10.1128/JCM.43.2.956-958.2005pmc: PMC548121pubmed: 15695717google scholar: lookup
  23. Stepanovic S, Jezek P, Vukovic D, Dakic I, Petras P. Isolation of members of the Staphylococcus sciuri group from urine and their relationship to urinary tract infections.. J. Clin. Microbiol. 2003;41:5262–5264.
    doi: 10.1128/JCM.41.11.5262-5264.2003pmc: PMC262515pubmed: 14605178google scholar: lookup
  24. Mazal C, Sieger B. Staphylococcus lentus: The troublemaker.. Int. J. Infect. Dis. 2010;14:e397.
    doi: 10.1016/j.ijid.2010.02.502google scholar: lookup
  25. Rivera M, Dominguez M.D, Mendiola N.R, Roso G.R, Quereda C. Staphylococcus lentus peritonitis: A case report.. Perit. Dial. Int. 2014;34:469–470.
    doi: 10.3747/pdi.2012.00303pmc: PMC4079497pubmed: 24991057google scholar: lookup
  26. Hay C.Y, Sherris D.A. Staphylococcus lentus sinusitis: A new sinonasal pathogen.. Ear Nose Throat J. 2020;99:NP62–NP63.
    doi: 10.1177/0145561319848990pubmed: 31072191google scholar: lookup
  27. Giordano N, Corallo C, Miracco C, Papakostas P, Montella A, Figura N, Nuti R. Erythema nodosum associated with Staphylococcus xylosus septicemia.. J. Microbiol. Immunol. Infect. 2016;49:134–137.
    doi: 10.1016/j.jmii.2012.10.003pubmed: 23266237google scholar: lookup
  28. Brand Y.E, Rufer B. Late prosthetic knee joint infection with Staphylococcus xylosus.. ID Cases 2021;24:e01160.
    doi: 10.1016/j.idcr.2021.e01160pmc: PMC8138718pubmed: 34036044google scholar: lookup
  29. Novaková D, Sedláček I, Pantuček R, Štètina V, Švec P, Petráš P. Staphylococcus equorum and Staphylococcus succinus isolated from human clinical specimens.. J. Med. Microbiol. 2006;55:523–528.
    doi: 10.1099/jmm.0.46246-0pubmed: 16585638google scholar: lookup
  30. Khusro A, Aarti C, Barbabosa-Pilego A, Hernández S.H. Anti-pathogenic, antibiofilm, and technological properties of fermented food associated Staphylococcus succinus strain AAS2.. Prep. Biochem. Biotechnol. 2019;49:176–183.
    doi: 10.1080/10826068.2019.1566149pubmed: 30688152google scholar: lookup
  31. Shields BE, Tschetter AJ, Wanat KA. Staphylococcus simulans: An emerging cutaneous pathogen.. JAAD Case Rep. 2016;2:428–429.
    doi: 10.1016/j.jdcr.2016.08.015pmc: PMC5143409pubmed: 27957522google scholar: lookup
  32. Vallianou N, Evangelopoulos A, Makri P, Zacharias G, Stefanitsi P, Karachalios A. Vertebral osteomyelitis and native valve endocarditis due to Staphylococcus simulans: A case report.. J. Med. Case Rep. 2008;2:183.
    doi: 10.1186/1752-1947-2-183pmc: PMC2426703pubmed: 18510763google scholar: lookup
  33. Yu Y, Dong Q, Li S, Qi H, Tan X. Etiology and clinical characteristics of neonatal sepsis in different medical setting models: A retrospective multi-center study.. Front. Pediatr. 2022;5:1004750.
    doi: 10.3389/fped.2022.1004750pmc: PMC9581286pubmed: 36275054google scholar: lookup
  34. Razonable RR, Lewallen DG, Patel R, Osmon DR. Vertebral osteomyelitis and prosthetic joint infection due to Staphylococcus simulans.. Mayo. Clin. Proc. 2001;76:1067–1070.
    doi: 10.4065/76.10.1067pubmed: 11605694google scholar: lookup
  35. Hosoya S, Kutsuna S, Shiojiri D, Tamura S, Isaka E, Wakimoto Y. Leuconostoc lactis and Staphylococcus nepalensis bacteremia, Japan.. Emerg. Infect. Dis. 2020;26:2283–2285.
    doi: 10.3201/eid2609.191123pmc: PMC7454056pubmed: 32818417google scholar: lookup
  36. Karakulska J, Fijałkowski K, Nawrotek P, Pobucewicz A, Poszumski F, Czernomysy-Furowicz D. Identification and methicillin resistance of coagulase-negative staphylococci isolated from nasal cavity of healthy horses.. J. Microbiol. 2012;50:444–451.
    doi: 10.1007/s12275-012-1550-6pubmed: 22752908google scholar: lookup
  37. Burton S, Reid-Smith R, McClure JT, Weese JS. Staphylococcus aureus colonization in healthy horses in Atlantic Canada.. Can. Vet. J. 2008;49:797–799.
    pmc: PMC2465786pubmed: 18978975
  38. Mota SL, dos Santos LO, Vidaletti MR, Rodrigues RO, Coppola MM, Mayer FQ. Antimicrobial resistance of coagulase-positive Staphylococcus isolated from healthy Crioulo horses and associated risk factors.. J. Equine Vet. Sci. 2021;107:103779.
    doi: 10.1016/j.jevs.2021.103779pubmed: 34802621google scholar: lookup
  39. Isgren CM, Williams NJ, Fletcher OD, Timofte D, Newton RJ, Maddox TW. Antimicrobial resistance in clinical bacterial isolates from horses in the UK.. Equine Vet. J. 2021;54:390–414.
    doi: 10.1111/evj.13437pubmed: 33566383google scholar: lookup
  40. Saputra S, Jordan D, Worthing KA, Norris JM, Wong HS, Abraham R. Antimicrobial resistance in coagulase-positive staphylococci isolated from companion animals in Australia: A one year study.. PLoS ONE 2017;12:e0176379.
    doi: 10.1371/journal.pone.0176379pmc: PMC5400250pubmed: 28430811google scholar: lookup
  41. Dubois D, Leyssene D, Chacornac JP, Kostrzewa M, Schmit PO, Talon R, Bonnet R, Delmas J. Identification of a variety of Staphylococcus species by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.. J. Clin. Microbiol. 2009;48:941–945.
    doi: 10.1128/JCM.00413-09pmc: PMC2832446pubmed: 20032251google scholar: lookup
  42. . Performance Standards for Antimicrobial Susceptibility Testing, 34th Ed.. CLSI M100-ED32:2022 .
  43. . Breakpoint Tables for Interpretation of MICs and Zone Diameters, Version 15.0.. European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2025.
  44. Sawant AA, Gillespie BE, Oliver SP. Antimicrobial susceptibility of coagulase-negative Staphylococcus species isolated from bovine milk.. Vet. Microbiol. 2009;134:73–81.
    doi: 10.1016/j.vetmic.2008.09.006pubmed: 18950969google scholar: lookup
  45. Nawaz M, Khan SA, Khan AA, Khambaty FM, Cerniglia CE. Comparative molecular analysis of erythromycin-resistance determinants in staphylococcal isolates of poultry and human origin.. Mol. Cell. Probes. 2000;14:311–319.
    doi: 10.1006/mcpr.2000.0320pubmed: 11040095google scholar: lookup
  46. Chajęcka-Wierzchowska W, Zadernowska A, Nalepa B, Sierpińska M, Łaniewska-Trokenheim L. Coagulase-negative staphylococci (CoNS) isolated from ready-to-eat food of animal origin--phenotypic and genotypic antibiotic resistance.. Food Microbiol. 2015;46:222–226.
    doi: 10.1016/j.fm.2014.08.001pubmed: 25475289google scholar: lookup
  47. Gómez-Sanz E, Torres C, Lozano C, Fernández-Pérez R, Aspiroz C, Ruiz-Larrea F, Zarazaga M. Detection, molecular characterization, and clonal diversity of methicillin-resistant Staphylococcus aureus CC398 and CC97 in Spanish slaughter pigs of different age groups.. Foodborne Pathog. Dis. 2010;7:1269–1277.
    doi: 10.1089/fpd.2010.0610pubmed: 20677918google scholar: lookup
  48. Ardic N, Sareyyupoglu B, Ozyurt M, Haznedaroglu T, Ilga U. Investigation of aminoglycoside modifying enzyme genes in methicillin-resistant staphylococci.. Microbiol. Res. 2006;161:49–54.
    doi: 10.1016/j.micres.2005.05.002pubmed: 16338590google scholar: lookup
  49. Le Bouter A, Leclercq R, Cattoir V. Molecular basis of resistance to macrolides, lincosamides and streptogramins in Staphylococcus saprophyticus clinical isolates.. Int. J. Antimicrob. Agents. 2011;37:118–123.
    doi: 10.1016/j.ijantimicag.2010.10.008pubmed: 21185697google scholar: lookup

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,970 horse owners like you who receive our email updates on horse health and nutrition.