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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

References

This article includes 53 references
  1. Samuelson DA, Andresen TL, Gwin RM. Conjunctival fungal flora in horses, cattle, dogs, and cats.. J Am Vet Med Assoc 1984;184(10):1240-1242.
  2. Andrew SE, Nguyen A, Jones GL, Brooks DE. Seasonal effects on the aerobic bacterial and fungal conjunctival flora of normal thoroughbred brood mares in Florida.. Vet Ophthalmol 2003;6(1):45-50.
  3. Brooks DE, Andrew SE, Dillavou CL, Ellis G, Kubilis PS. Antimicrobial susceptibility patterns of fungi isolated from horses with ulcerative keratomycosis.. Am J Vet Res 1998;59(2):138-142.
  4. Pearce JW, Giuliano EA, Moore CP. In vitro susceptibility patterns of aspergillus and fusarium species isolated from equine ulcerative keratomycosis cases in the midwestern and southern United States with inclusion of the new antifungal agent voriconazole.. Vet Ophthalmol 2009;12(5):318-324.
  5. Reed Z, Thomasy SM, Good KL. Equine keratomycoses in California from 1987 to 2010 (47 cases).. Equine Vet J 2013;45(3):361-366.
  6. Sherman AB, Clode AB, Gilger BC. Impact of fungal species cultured on outcome in horses with fungal keratitis.. Vet Ophthalmol 2017;20(2):140-146.
  7. Ledbetter EC. Antifungal therapy in equine ocular mycotic infections.. Vet Clin North Am Equine Pract 2017;33(3):583-605.
  8. Ledbetter EC, Patten VH, Scarlett JM, Vermeylen FM. In vitro susceptibility patterns of fungi associated with keratomycosis in horses of the northeastern United States: 68 cases (1987-2006).. J Am Vet Med Assoc 2007;231(7):1086-1091.
  9. Mitchell JS, Attleberger MH. Fusarium keratomycosis in the horse.. Vet Med Small Anim Clin 1973;68(11):1257-1260.
  10. Betbeze CM, Wu CC, Krohne SG, Stiles J. In vitro fungistatic and fungicidal activities of silver sulfadiazine and natamycin on pathogenic fungi isolated from horses with keratomycosis.. Am J Vet Res 2006;67(10):1788-1793.
  11. O'Day DM, Head WS, Robinson RD, Clanton JA. Corneal penetration of topical amphotericin B and natamycin.. Curr Eye Res 1986;5(11):877-882.
  12. O'Day DM, Ray WA, Head WS, Robinson RD. Influence of the corneal epithelium on the efficacy of topical antifungal agents.. Invest Ophthalmol Vis Sci 1984;25(7):855-859.
  13. Hariprasad SM, Mieler WF, Lin TK, Sponsel WE, Graybill JR. Voriconazole in the treatment of fungal eye infections: a review of current literature.. Br J Ophthalmol 2008;92(7):871-878.
  14. Ansari Z, Miller D, Galor A. Current thoughts in fungal keratitis: diagnosis and treatment.. Curr Fungal Infect Rep 2013;7(3):209-218.
  15. Azor M, Cano J, Gené J, Guarro J. High genetic diversity and poor in vitro response to antifungals of clinical strains of fusarium oxysporum.. J Antimicrob Chemother 2009;63(6):1152-1155.
  16. Azor M, Gené J, Cano J, Guarro J. Universal in vitro antifungal resistance of genetic clades of the fusarium solani species complex.. Antimicrob Agents Chemother 2007;51(4):1500-1503.
  17. Kumari N, Xess A, Shahi S. A study of keratomycosis: our experience.. Indian J Pathol Microbiol 2002;45(3):299-302.
  18. Pfaller M, Messer S, Hollis R, Jones R. Antifungal activities of posaconazole, ravuconazole, and voriconazole compared to those of itraconazole and amphotericin B against 239 clinical isolates of aspergillus spp. and other filamentous fungi: report from SENTRY antimicrobial surveillance program, 2000.. Antimicrob Agents Chemother 2002;46(4):1032-1037.
  19. Lalitha P, Shapiro BL, Srinivasan M. Antimicrobial susceptibility of fusarium, aspergillus, and other filamentous fungi isolated from keratitis.. Arch Ophthalmol 2007;125(6):789-793.
  20. Pujol I, Guarro J, Gene J, Sala J. In-vitro antifungal susceptibility of clinical and environmental fusarium spp. strains.. J Antimicrob Chemother 1997;39(2):163-167.
  21. Taylan Sekeroglu H, Erdem E, Yagmur M. Successful medical management of recalcitrant fusarium solani keratitis: molecular identification and susceptibility patterns.. Mycopathologia 2012;174(3):233-237.
  22. Xie L, Zhai H, Zhao J, Sun S, Shi W, Dong X. Antifungal susceptibility for common pathogens of fungal keratitis in Shandong Province, China.. Am J Ophthalmol 2008;146(2):260-265.
  23. Odds FC, Brown AJ, Gow NA. Antifungal agents: mechanisms of action.. Trends Microbiol 2003;11(6):272-279.
  24. Turenne CY, Sanche SE, Hoban DJ, Karlowsky JA, Kabani AM. Rapid identification of fungi by using the ITS2 genetic region and an automated fluorescent capillary electrophoresis system.. J Clin Microbiol 1999;37(6):1846-1851.
  25. John H. Reference method for broth dilution antifungal susceptibility testing of filamentous fungi, approved standard. M38-A2.. Clin Lab Stand Inst 2008;28(16):1-35.
  26. Cuenca-Estrella M. Antifungal drug resistance mechanisms in pathogenic fungi: from bench to bedside.. Clin Microbiol Infect 2014;20:54-59.
  27. Iqbal NJ, Boey A, Park BJ, Brandt ME. Determination of in vitro susceptibility of ocular fusarium spp. isolates from keratitis cases and comparison of clinical and laboratory standards institute M38-A2 and E test methods.. Diagn Microbiol Infect Dis 2008;62(3):348-350.
  28. Marangon FB, Miller D, Giaconi JA, Alfonso EC. In vitro investigation of voriconazole susceptibility for keratitis and endophthalmitis fungal pathogens.. Am J Ophthalmol 2004;137(5):820-825.
  29. Oechsler RA, Feilmeier MR, Miller D, Shi W, Hofling-Lima AL, Alfonso EC. Fusarium keratitis: genotyping, in vitro susceptibility and clinical outcomes.. Cornea 2013;32(5):667-673.
  30. Brooks DE, Plummer CE, Mangan BG, Ben-Shlomo G. Equine subepithelial keratomycosis.. Vet Ophthalmol 2013;16(2):93-96.
  31. Clode AB, Davis JL, Salmon J, Michau TM, Gilger BC. Evaluation of concentration of voriconazole in aqueous humor after topical and oral administration in horses.. Am J Vet Res 2006;67(2):296-301.
  32. Galán A, Martín-Suárez E, Gallardo J, Molleda J. Clinical findings and progression of 10 cases of equine ulcerative keratomycosis (2004-2007).. Equine Vet Educ 2009;21(5):236-242.
  33. Thomas P. Fungal infections of the cornea.. Eye 2003;17(8):852-862.
  34. Whitley R, Burgess EC, Moore C. Microbial isolates of the normal equine eye.. Equine Vet J 1983;15(S2):138-140.
  35. Roberts D, Cotter HVT, Cubeta M, Gilger BC. In vitro susceptibility of aspergillus and fusarium associated with equine keratitis to new antifungal drugs.. Vet Ophthalmol 2020;23(5):918-922.
  36. Ozturk F, Yavas GF, Kusbeci T. Efficacy of topical caspofungin in experimental fusarium keratitis.. Cornea 2007;26(6):726-728.
  37. Patil A, Majumdar S. Echinocandins in ocular therapeutics.. J Ocul Pharmacol Ther 2017;33(5):340-352.
  38. Andrew SE, Brooks DE, Smith PJ, Gelatt KN, Chmielewski NT, Whittaker CJ. Equine ulcerative keratomycosis: visual outcome and ocular survival in 39 cases (1987-1996).. Equine Vet J 1998;30(2):109-116.
  39. Ghannoum MA, Rex JH, Galgiani JN. Susceptibility testing of fungi: current status of correlation of in vitro data with clinical outcome.. J Clin Microbiol 1996;34(3):489-495.
  40. Kuzucu C, Rapino B, McDermott L, Hadley S. Comparison of the semisolid agar antifungal susceptibility test with the NCCLS M38-P broth microdilution test for screening of filamentous fungi.. J Clin Microbiol 2004;42(3):1224-1227.
  41. White TC, Marr KA, Bowden RA. Clinical, cellular, and molecular factors that contribute to antifungal drug resistance.. Clin Microbiol Rev 1998;11(2):382-402.
  42. Ha KC, White TC. Effects of azole antifungal drugs on the transition from yeast cells to hyphae in susceptible and resistant isolates of the pathogenic yeast Candida albicans.. Antimicrob Agents Chemother 1999;43(4):763-768.
  43. Lees ND, Broughton M, Sanglard D, Bard M. Azole susceptibility and hyphal formation in a cytochrome P-450-deficient mutant of Candida albicans.. Antimicrob Agents Chemother 1990;34(5):831-836.
  44. Brand A. Hyphal growth in human fungal pathogens and its role in virulence.. Int J Microbiol 2011;2012:1-11.
  45. Boveland SD, Moore PA, Mysore J. Immunohistochemical study of matrix metalloproteinases-2 and-9, macrophage inflammatory protein-2 and tissue inhibitors of matrix metalloproteinases-1 and-2 in normal, purulonecrotic and fungal infected equine corneas.. Vet Ophthalmol 2010;13(2):81-90.
  46. Gelatt KN. Veterinary Ophthalmology.. 4th ed. Blackwell Pub; 2007.
  47. Gilger BC. Immunology of the ocular surface.. Vet Clin N Am Small Anim Pract 2008;38(2):223-231.
  48. Ollivier F, Gilger B, Barrie K. Proteinases of the cornea and preocular tear film.. Vet Ophthalmol 2007;10(4):199-206.
  49. Scotty NC. Equine keratomycosis.. Clin Tech Equine Pract 2005;4(1):29-36.
  50. Scotty NC, Brooks DE, Schuman Rose CD. In vitro efficacy of an ophthalmic drug combination against corneal pathogens of horses.. Am J Vet Res 2008;69(1):101-107.
  51. Weinstein WL, Moore PA, Sanchez S, Dietrich UM, Wooley RE, Ritchie BW. In vitro efficacy of a buffered chelating solution as an antimicrobial potentiator for antifungal drugs against fungal pathogens obtained from horses with mycotic keratitis.. Am J Vet Res 2006;67(4):562-568.
  52. Vorwerk CK, Tuchen S, Streit F, Binder L, Hofmuller W, Behrens-Baumann W. Aqueous humor concentrations of topically administered caspofungin in rabbits.. Ophthalmic Res 2009;41(2):102-105.
  53. Philip A, Odabasi Z, Rodriguez J. In vitro synergy testing of anidulafungin with itraconazole, voriconazole, and amphotericin B against aspergillus spp. and fusarium spp.. Antimicrob Agents Chemother 2005;49(8):3572-3574.

Citations

This article has been cited 7 times.
  1. Saenz V, Lizcano-Salas AF, Le Pape P, Celis Ramírez AM. Antifungal and fungicide susceptibility of clinical, animal, and environmental Fusarium and Neocosmospora species from Colombia: a one-health approach. Sci Rep 2025 Dec 17;16(1):2515.
    doi: 10.1038/s41598-025-32234-0pubmed: 41407882google scholar: lookup
  2. Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
    doi: 10.1111/avj.70003pubmed: 40903020google scholar: lookup
  3. Dieste-Pérez L, Holstege MMC, de Jong JE, Heuvelink AE. Azole resistance in Aspergillus isolates from animals or their direct environment (2013-2023): a systematic review. Front Vet Sci 2025;12:1507997.
    doi: 10.3389/fvets.2025.1507997pubmed: 40182641google scholar: lookup
  4. Debergh H, Haesendonck R, Botteldoorn N, Martel A, Pasmans F, Saegerman C, Packeu A. Pan-azole resistance in clinical Aspergillus fumigatus isolates carrying TR34/L98H from birds and mammals in Belgium. One Health 2024 Dec;19:100907.
    doi: 10.1016/j.onehlt.2024.100907pubmed: 39430230google scholar: lookup
  5. Roberts D, Thomas J, Salmon J, Cubeta MA, Stapelmann K, Gilger BC. Cold atmospheric plasma inactivates Aspergillus flavus and Fusarium keratoplasticum biofilms and conidia in vitro. J Med Microbiol 2024 Jul;73(7).
    doi: 10.1099/jmm.0.001858pubmed: 38985505google scholar: lookup
  6. Roberts D, Salmon J, Cubeta MA, Gilger BC. Phase-Dependent Differential In Vitro and Ex Vivo Susceptibility of Aspergillus flavus and Fusarium keratoplasticum to Azole Antifungals. J Fungi (Basel) 2023 Sep 26;9(10).
    doi: 10.3390/jof9100966pubmed: 37888221google scholar: lookup
  7. Hisey EA, Martins BC, Donnelly CG, Cassano JM, Katzman SA, Murphy CJ, Thomasy SM, Leonard BC. Identification of putative orthologs of clinically relevant antimicrobial peptides in the equine ocular surface and amniotic membrane. Vet Ophthalmol 2023 Apr;26 Suppl 1(Suppl 1):125-133.
    doi: 10.1111/vop.13042pubmed: 36478371google scholar: lookup
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