Malassezia species isolated from the intermammary and preputial fossa areas of horses.

This research demonstrates the presence of Malassezia yeast in certain areas of both healthy mares and geldings. Despite this food, the pathogenic role of the yeast is ambiguous as it could be a part of the normal flora of these equine species.

Objectives and Methods

The goal of the study was to identify the presence of Malassezia yeast in the intermammary region of healthy mares and the preputial fossa in healthy geldings. Researchers sampled surface materials from:

• Five mares in the intermammary region.
• Six geldings in the preputial fossa region.

These samples were examined both cytologically and by culturing on modified Sabouraud’s dextrose agar. The DNA from yeast colonies grown on the agar was then extracted and tested using a generic fungal polymerase chain reaction (PCR) analysis. This PCR analysis enables a substantial increase in a specific DNA segment. The amplicons, the DNA pieces resulting from the PCR reaction, that yielded positive PCR results were then sequenced and compared with sequences in the BLAST database search program.

Results

Out of 44 attempts at culture, only seven yielded Malassezia species:

• Five samples identified as Malassezia equi.
• Two samples identified as M slooffiae.

However, the cytologic examination was far more reliable with Malassezia spp. morphology revealed in 40 out of 44 samples.

Conclusions

The conclusion drawn from the research was that due to its presence in healthy horses, Malassezia-type yeast found on cytologic examination may not necessarily indicate a pathogen. In effect, while Malassezia may be present, it doesn’t definitively signal disease. The study also noted that cytologic examination, in comparison to culturing, was a more effective and rapid tool for demonstrating the organism’s presence. This implies a need for further study to establish the potential pathogenicity of these types of yeasts in these equine species.