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Home / Equine Research Bank / Vet Ophthalmol / In vitro antifungal susceptibility of Fusarium species and A...
Veterinary ophthalmology2022; 25(5); 376-384; doi: 10.1111/vop.12995

In vitro antifungal susceptibility of Fusarium species and Aspergillus fumigatus cultured from eleven horses with fungal keratitis.

Abstract: To examine the relationship between Minimum Inhibitory Concentration (MICs) and response to therapy of 6 Fusarium spp. and 5 Aspergillus fumigatus isolated from equine ulcerative keratitis cases. Methods: Fungi were identified by morphology and Internal Transcribed Spacer (ITS) polymerase chain reaction (PCR) with sequencing and evaluated at the University of Texas Fungal Testing Laboratory for susceptibility to three azole antifungals (miconazole, voriconazole, posaconazole), natamycin, and two echinocandins (anidulafungin, caspofungin). A Mann-Whitney rank sum test was used for the comparison of time to heal between infections of different fungal genera and in vitro susceptibility to the drug administered. Results: Fusarium spp. were resistant to azole antifungals in 6/6 cases (100%). Fusarium spp. were susceptible to echinocandins and natamycin in all cases. A. fumigatus was resistant to anidulafungin in 1/5 cases (20%) and posaconazole in 1/5 cases (20%) The remainder of A. fumigatus isolates were susceptible to all antifungal agents tested. Fusarium isolates were treated with antifungals to which they were not susceptible; however, all cases of A. fumigatus were treated with antifungals to which they were susceptible. All Fusarium cases and A. fumigatus cases experienced clinical resolution, regardless of surgical intervention. There was no statistical correlation between fungal genus and time to heal (p < .082). Conclusions: The in vitro susceptibility indicated that all cases of Fusarium spp. were resistant to azole antifungal drugs which were used as treatment. Clinical outcomes, however, showed that all cases healed despite resistance to antifungals.
© 2022 American College of Veterinary Ophthalmologists.
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Publication Date: 2022-06-09 PubMed ID: 35684950DOI: 10.1111/vop.12995Google 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.

The study investigates the susceptibility of two types of fungi, Fusarium and Aspergillus fumigatus, collected from cases of horse eye infection, to different antifungal drugs. It was found that all Fusarium species were resistant to a group of antifungals known as azoles, however, they were susceptible to other drugs, and all cases healed whether or not the fungi were resistant to the treatment used.

Research Objectives and Methods

  • The main aim of this research was to explore the connection between the Minimum Inhibitory Concentration (MICs) and the therapy response of 6 Fusarium species and 5 isolates of Aspergillus fumigatus. All these fungi were gathered from instances of horse ulcerative keratitis.
  • The identification of the fungi was based on their morphology and Internal Transcribed Spacer (ITS) polymerase chain reaction (PCR) with sequencing.
  • Susceptibility to three types of azole antifungals (miconazole, voriconazole, posaconazole), natamycin, and two types of echinocandins (anidulafungin, caspofungin) was tested in University of Texas’s Fungal Testing Laboratory.
  • A special statistical test, Mann-Whitney rank sum test, was used to compare the healing process duration between infections caused by different fungal genera and in vitro susceptibility to the medication used.

Results of the Study

  • All Fusarium species showed resistance to azole antifungals in the lab tests. However, they were susceptible to echinocandins and natamycin.
  • Aspergillus fumigatus demonstrated resistance to anidulafungin and posaconazole in 1/5 instances. The remaining isolates were susceptible to all antifungals tested.
  • Although Fusarium isolates were treated with antifungals to which they were resistant, all cases healed. In contrast, all cases of Aspergillus fumigatus were treated with drugs to which they were vulnerable and all of them also healed resourcefully.
  • The research failed to identify a statistical correlation between the fungal genus and time to healing (p < .082).

Conclusions from the Study

  • The lab-based susceptibility tests revealed that all cases of Fusarium species were resistant to azole type of antifungal drugs used in the treatment process.
  • The healing outcomes of horses showed that all cases experienced clinical resolution, whether or not surgery was introduced to the treatment process, regardless of the lab-based drug resistance outcome.

Cite This Article

APA
Martinez PS, Whitley RD, Plummer CE, Richardson RL, Hamor RE, Wellehan JFX. (2022). In vitro antifungal susceptibility of Fusarium species and Aspergillus fumigatus cultured from eleven horses with fungal keratitis. Vet Ophthalmol, 25(5), 376-384. https://doi.org/10.1111/vop.12995

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 25
Issue: 5
Pages: 376-384

Researcher Affiliations

Martinez, Paoul S
  • Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, USA.
Whitley, R David
  • Department of Small Animal Clinical Sciences, Professor Emeritus, University of Florida, Gainesville, Florida, USA.
Plummer, Caryn E
  • Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, USA.
  • Department of Large Animal Clinical Sciences, University of Florida, Gainesville, Florida, USA.
Richardson, Rebecca L
  • Clinical Microbiology, Parasitology and Serology, University of Florida, Gainesville, Florida, USA.
Hamor, Ralph E
  • Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, USA.
Wellehan, James F X
  • Department of Comparative, Diagnostic & Population Medicine, University of Florida, Gainesville, Florida, USA.

MeSH Terms

  • Anidulafungin / therapeutic use
  • Animals
  • Antifungal Agents / pharmacology
  • Antifungal Agents / therapeutic use
  • Aspergillus fumigatus
  • Corneal Ulcer / drug therapy
  • Corneal Ulcer / microbiology
  • Corneal Ulcer / veterinary
  • Echinocandins
  • Eye Infections, Fungal / drug therapy
  • Eye Infections, Fungal / microbiology
  • Eye Infections, Fungal / veterinary
  • Fusarium
  • Horses
  • Microbial Sensitivity Tests / veterinary
  • Natamycin / pharmacology
  • Natamycin / therapeutic use
  • Voriconazole / therapeutic use

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