Retrospective study on equine uterine fungal isolates and antifungal susceptibility patterns (1999–2011)



Reasons for performing study: Knowledge of commonly encountered fungi infecting the mare's reproductive tract and their respective drug susceptibilities should improve treatment efficacy in mares with fungal endometritis. This is particularly important when practitioners need to start empiric treatment before culture results are complete.

Objective: To report the spectrum of fungal isolates from uterine samples from mares with reproductive problems and their respective antifungal susceptibilities.

Methods: Equine uterine samples submitted to the Cornell University Animal Health Diagnostic Centre for fungal culture between July 1999 and June 2011 were reviewed. Each mare's reproductive history, fungal culture results, antifungal susceptibilities and concurrent aerobic culture results were evaluated. Patterns of antifungal susceptibility and resistance were assessed over time.

Results: One hundred and two fungal isolates were cultured from 92 uterine samples from mares with reproductive problems. Yeast (69%) and mould with septated hyphae (26%) were the most common isolates. Ninety-five to 100% of all fungal isolates were susceptible to the polyenes, while response to the azoles varied with 47–81% of fungal isolates displaying susceptibility. Yeast isolates were 100% susceptible to the polyenes and least susceptible to miconazole (48%) while isolates of mould with septated hyphae were most susceptible to natamycin (100%) and least susceptible to fluconazole (0%). From July 1999 to June 2005 and July 2005 to June 2011, yeast demonstrated increasing resistance to miconazole, while mould with septated hyphae demonstrated increasing resistance to ketoconazole.

Conclusions and clinical relevance: Results from this study suggest that polyenes are effective against uterine fungal isolates in vitro and may be the empiric treatment of choice for fungal endometritis. Isolate resistance to specific azoles increased over time.