In vitro susceptibility patterns of fungi associated with keratomycosis in horses of the northeastern United States: 68 cases (1987-2006).
OBJECTIVE
To determine in vitro susceptibility patterns of fungi associated with keratomycosis in horses in the northeastern United States and compare those patterns with results of studies from other geographic regions.


METHODS
Retrospective case series.


METHODS
68 horses with keratomycosis.


METHODS
Medical records of horses with a clinical diagnosis of keratomycosis, positive results of corneal fungal cultures, and susceptibility data were reviewed from the years 1987 to 2006. Fungal identification and in vitro antifungal susceptibility test results were recorded. The percentage of susceptible isolates was compared among antifungals for all isolates together and for the most common genera individually.


RESULTS
74 fungal isolates from 68 horses that met inclusion criteria were identified. Aspergillus, Candida, and Fusarium spp were the most frequent isolates. Grouped isolates had the highest percentage of susceptibility to nystatin (87.7%), natamycin (87.5%), and clotrimazole (80.6%). Grouped isolates had the lowest percentage of susceptibility to fluconazole (15.8%) and miconazole (27.5%). Aspergillus spp (> or = 81.0%) were most susceptible to nystatin, clotrimazole, itraconazole, and natamycin. Candida spp (100%) were most susceptible to ketaconazole, natamycin, and nystatin. Fusarium spp (100%) were only consistently susceptible to natamycin.


CONCLUSIONS
On the basis of in vitro susceptibility testing, nystatin, natamycin, or clotrimazole is recommended for initial topical treatment of keratomycosis in horses from the northeastern United States. Contrary to results of studies of ocular fungal isolates of horses from other regions, Candida spp were identified more frequently and miconazole had lower in vitro efficacy in the present study.
Ledbetter
Eric C
EC
Department of Clinical Sciences, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA.
Patten
Valeri H
VH
Scarlett
Janet M
JM
Vermeylen
Francoise M
FM
D000818:Animals; D000935:Antifungal Agents / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D025141:Drug Resistance, Fungal; D015821:Eye Infections, Fungal / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D005260:Female; D005658:Fungi / Q000187:drug effects*; D006734:Horse Diseases / Q000188:drug therapy* / Q000382:microbiology*; D006736:Horses; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D009511:New England; D012189:Retrospective Studies; D016896:Treatment Outcome
D000935:Antifungal Agents