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Home / Equine Research Bank / Antibiotics (Basel) / Analysis of Staphylococcal Diversity in the Skin Microbiota ...
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 (, ).
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Publication Date: 2025-10-16 PubMed ID: 41148728PubMed Central: PMC12561800DOI: 10.3390/antibiotics14101037Google Scholar: Lookup
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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.

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