Virulence determinants of Malassezia pachydermatis isolated from cases of canine dermatitis

Abstract

Malassezia is a commensal organism known to cause disease under favourable conditions, and has been isolated from many animals as well as human beings. Malassezia pachydermatis is the most common cause of yeast dermatitis in dogs and there are many determinants involved in the production of disease in the host. This study aims to deterimine the presence of virulent determinants of the organisms isolated from fifteen dogs with dermatitis that may be involved in the pathogenic mechanism of Malassezia. The virulence determinants of M. pachydermatis viz; adherence, cellular surface hydrophobicity and biofilm formation were investigated. All the isolates studied were shown to produce all the virulent factors investigated in vitro which can be compared to the biological system. Adherence of organism on polystyrene plates was evident in all the isolates and the values ranged from 0.14 to 63 per cent with five isolates showing high adherence values. Hydrophobicity was variable and ranged from 1.78 to 69.46 per cent by two phase system with seven isolates showing moderate property. All the isolates were shown to produce biofilm by crystal violet staining technique and the optical density values ranged from 0.075 to 0.56 at 620 nm. No significant correlation was observed between the three virulent determinants examined. The presence of three virulent determinants investigated warrants their consideration in further studies for assessing the pathogenicity of Malassezia dermatitis in dogs.

Keywords

• malassezia
• adherence
• cellular surface hydrophobicity
• biofilm