Clostridioides difficile in feral horse populations in Australia.
Abstract: Clostridioides difficile is a known cause of diarrhea and colitis in human and non-human animals. While C. difficile is regularly isolated from domesticated horses, little is known about its prevalence in wild or feral populations. In Australia, the horse population encompasses a mix of both domesticated and feral animals, with the feral population of 400,000 estimated to be the largest in the world. This study investigated the presence and characteristics of C. difficile in Australian feral horses and evaluated their potential as a source or reservoir of C. difficile in the wider community. Fecal samples (n = 380) were collected from free-roaming feral horses from five Australian jurisdictions and cultured for C. difficile. Isolates were characterized by PCR ribotyping and toxin profiling. Antimicrobial susceptibility testing was performed for fidaxomicin, vancomycin, metronidazole, rifaximin, clindamycin, erythromycin, amoxicillin-clavulanate, moxifloxacin, meropenem, and tetracycline. C. difficile was isolated from 45 of the 380 samples (11.8%)-one-third of that seen in recent studies on Australian domesticated horses but consistent with wild animal species worldwide. Forty ribotypes (RTs) were identified, 28 of which (70%) were novel; other RTs had been previously reported in humans, livestock, and soils. Eighteen toxigenic C. difficile strains were isolated, of which eight contain binary toxin genes. Strains were largely susceptible to the antimicrobial agents tested. This investigation provides preliminary information on C. difficile in feral horses in Australia and allows a comparison with their domestic counterparts. The findings support the hypothesis that all horse feces represent a potential source of C. difficile in the community. Objective: Clostridioides difficile poses an ongoing threat to healthcare in the community, with increasing evidence of transmission outside the hospital setting. In keeping with a One Health model of dispersion, investigations into this microorganism within the wider environment are vital to understanding this evolving epidemiology. Australia has the biggest population of feral horses in the world, and this study of C. difficile in feral horses provides insight into the role of non-domesticated animals in the dissemination of C. difficile. Examination of prevalence and characterization of isolates provides a baseline for evaluating the effect of antimicrobials and other factors associated with domestication on equine C. difficile infection.
Publication Date: 2025-04-02 PubMed ID: 40172204PubMed Central: PMC12093960DOI: 10.1128/aem.02114-24Google Scholar: Lookup
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Summary
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The research paper is a study on the prevalence and characteristics of Clostridioides difficile (C. difficile) in feral horse populations in Australia, in comparison to their domestic counterparts, and their potential role in the spreading of C. difficile in the community.
Objective of the Study
- The primary goal was to investigate the presence and characteristics of C. difficile in feral horses in Australia and to contrast this with the disease’s presence in domestic horses.
- Another aspect of the study aimed to understand the potential role the feral horses might play in transmission of C. difficile within the community.
Methodology
- The researchers collected fecal samples from 380 free-roaming feral horses across five Australian jurisdictions and cultured these for C. difficile.
- The isolated C. difficile was characterized using PCR ribotyping and toxin profiling.
- Lastly, they conducted antimicrobial susceptibility testing against several drugs to see the resistance patterns of the isolated strains.
Findings
- Out of 380 samples, 45 (11.8%) were found positive for C. difficile. This prevalence is one third of what was seen in domesticated horses previously but aligns with the prevalence among wild animal species globally.
- A total of 40 ribotypes (RTs) were identified; out of which 28 (70%) were novel, and others had been reported previously in humans, livestock, and soils indicating a potential transmission path.
- 18 toxigenic C. difficile strains were isolated, eight of which contained binary toxin genes.
- The majority of the strains were seen to be susceptible to the tested antimicrobials which can be useful for treatment in case of infections.
Conclusion
- The study provides initial data on the C. difficile prevalence in feral horses of Australia and emphasizes the role of feces from all horse types as a potential source of this bacterium in the community.
- The results also support the notion of the One Health model, highlighting feral horses’ potential role in disseminating this bacteria beyond a hospital setting.
- The findings offer a basis to understand the effects of antimicrobials and other factors related to domestication on equine C. difficile infection.
Cite This Article
APA
Hain-Saunders NMR, Knight DR, Harvey A, Bruce M, Hampson BA, Riley TV.
(2025).
Clostridioides difficile in feral horse populations in Australia.
Appl Environ Microbiol, 91(5), e0211424.
https://doi.org/10.1128/aem.02114-24 Publication
Researcher Affiliations
- Biosecurity and One Health Research Centre, Harry Butler Institute, Murdoch University, Murdoch, Western Australia, Australia.
- Department of Microbiology, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia.
- School of Biomedical Sciences, The University of Western Australia, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia.
- Centre for Compassionate Conservation, School of Life Sciences, Faculty of Science, University of Technology Sydney, Broadway, New South Wales, Australia.
- Biosecurity and One Health Research Centre, Harry Butler Institute, Murdoch University, Murdoch, Western Australia, Australia.
- School of Veterinary Medicine, Murdoch University, Murdoch, Western Australia, Australia.
- Independent Researcher, Brisbane, Australia.
- Department of Microbiology, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia.
- School of Biomedical Sciences, The University of Western Australia, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia.
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.
MeSH Terms
- Animals
- Horses / microbiology
- Clostridioides difficile / isolation & purification
- Clostridioides difficile / genetics
- Clostridioides difficile / drug effects
- Clostridioides difficile / classification
- Australia / epidemiology
- Clostridium Infections / veterinary
- Clostridium Infections / epidemiology
- Clostridium Infections / microbiology
- Horse Diseases / microbiology
- Horse Diseases / epidemiology
- Anti-Bacterial Agents / pharmacology
- Feces / microbiology
- Animals, Wild / microbiology
- Ribotyping
- Microbial Sensitivity Tests
Grant Funding
- APP1138257 / DHAC | National Health and Medical Research Council (NHMRC)
Conflict of Interest Statement
The authors declare no conflict of interest.
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