Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland.
Abstract: To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. Methods: Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detected in samples from eyes with keratomycosis in Switzerland. Minimal inhibitory concentrations (MICs) for voriconazole, fluconazole, itraconazole, amphotericin B, and miconazole were recorded. Results: Fifty-nine of the horses were tested positive for fungal growth from at least one eye (92%). Eleven genera of fungi were identified. The most common fungal genera were Alternaria, Eurotium, Rhizopus, and Cladosporium. Aspergillus spp. and Penicillium spp. were isolated frequently, while no Fusarium spp. was found. In only 2 cases, yeasts were identified as Candida guilliermondii. For certain fungal species, the type of bedding and housing appeared to influence their prevalence. Susceptibility testing of A. fumigatus showed lowest MICs for voriconazole, E. amstelodami for voriconazole and itraconazole. High MICs for fluconazole were detected for all tested fungi while MICs for amphotericin B and miconazole were variable. Conclusions: A large range of fungal mold species was identified including A. fumigatus and E. amstelodami, which have been causative agents of keratomycosis in Switzerland. Best in vitro susceptibility results for these two species were obtained for voriconazole.
© 2013 American College of Veterinary Ophthalmologists.
Publication Date: 2013-08-02 PubMed ID: 23910390DOI: 10.1111/vop.12088Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article primarily evaluates the variety of fungal flora existing in the eyes of healthy horses in Switzerland and assesses the resistance of the common species to different antifungal medications.
Research Objectives and Methods
- The study aimed at identifying and recording the common types of conjunctival fungal flora that are found in healthy horses.
- 64 horses, all devoid of any ophthalmological issues, were thoroughly examined in August 2012 at The National Stud in Switzerland, and samples were collected from both eyes using a cytobrush.
- The gathered samples were then cultured on Sabouraud’s agar medium to enable fungal growth.
- Two molds particularly, Aspergillus fumigatus and Eurotium amstelodami, identified previously from eyes with keratomycosis in Switzerland, were tested with Etests or broth microdilution tests to evaluate their susceptibility towards various antifungal drugs.
Key Findings
- Out of the total horses tested, it was found that 92% of them had some fungal growth in at least one eye.
- A variety of 11 genera of fungi were identified from the sample, the most predominant ones being Alternaria, Eurotium, Rhizopus, and Cladosporium along with frequent findings of Aspergillus spp. and Penicillium spp.
- No Fusarium spp. was identified during the study, while yeasts, identified as Candida guilliermondii, were found only in 2 cases.
- It was also found that the prevalence of certain fungal species was influenced by the type of bedding and housing of the horses.
- The susceptibility tests showed that Aspergillus fumigatus was more susceptible to voriconazole, while Eurotium amstelodami was susceptible to both voriconazole and itraconazole.
- All tested fungi showed high Minimum Inhibitory Concentrations (MICs) for fluconazole, while the effect of amphotericin B and miconazole was variable across species.
Conclusions
- The research concludes with the identification of a wide variety of mold species in the eyes of horses, including those which have been causing keratomycosis in Switzerland – Aspergillus fumigatus and Eurotium amstelodami.
- The most effective antifungal drug in vitro for these species appeared to be voriconazole.
Cite This Article
APA
Voelter-Ratson K, Monod M, Unger L, Spiess BM, Pot SA.
(2013).
Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland.
Vet Ophthalmol, 17 Suppl 1, 31-36.
https://doi.org/10.1111/vop.12088 Publication
Researcher Affiliations
- Equine Department, Section of Ophthalmology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057, Zurich, Switzerland.
MeSH Terms
- Amphotericin B / pharmacology
- Animals
- Antifungal Agents / pharmacology
- Aspergillus fumigatus / drug effects
- Conjunctiva / microbiology
- Eurotium / drug effects
- Female
- Fluconazole / pharmacology
- Fungi / drug effects
- Fungi / isolation & purification
- Horses / microbiology
- Itraconazole / pharmacology
- Male
- Miconazole / pharmacology
- Microbial Sensitivity Tests / veterinary
- Switzerland / epidemiology
- Voriconazole / pharmacology
Citations
This article has been cited 5 times.- Lazareva Y, Rayisyan M, Mironova E. Features of the clinical picture of keratitis in horses with different forms of the course of the disease.. Open Vet J 2022 Nov-Dec;12(6):830-838.
- Nardi S, Puccini Leoni F, Monticelli V, Ebani VV, Bertelloni F, Marzoni M, Mancianti F, Citi S, Barsotti G. Tear Production, Intraocular Pressure, Ultrasound Biometric Features and Conjunctival Flora Identification in Clinically Normal Eyes of Two Italian Breeds of Chicken (Gallus gallus domesticus).. Animals (Basel) 2021 Oct 17;11(10).
- Walsh ML, Meason-Smith C, Arnold C, Suchodolski JS, Scott EM. Evaluation of the ocular surface mycobiota in clinically normal horses.. PLoS One 2021;16(2):e0246537.
- Mora-Pereira M, Abarca EM, Duran S, Ravis W, McMullen RJ Jr, Fischer BM, Lee YP, Wooldridge AA. Sustained-release voriconazole-thermogel for subconjunctival injection in horses: ocular toxicity and in-vivo studies.. BMC Vet Res 2020 Apr 16;16(1):115.
- Mustikka MP, Grönthal TSC, Pietilä EM. Equine infectious keratitis in Finland: Associated microbial isolates and susceptibility profiles.. Vet Ophthalmol 2020 Jan;23(1):148-159.
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