In Vitro Enzymatic Virulence Factors of Dermatophytes Species Isolated From Clinical Specimens

Dermatophytes are keratinophilic fungi that affect the stratum corneum of the skin and keratinous structures. Violent factors play a vital role in the pathogenesis and antifungal resistance of dermatophytes. 

This study aims to evaluate the activity of extracellular enzymatic and biofilm formation as virulence factors of dermatophyte isolates.

Fifty-eight dermatophyte isolates belonged to 27 Trichophyton. rubrum (46.6%), 19 T. mentagrophytes (32.8%), and 12 Microsporum. canis (20.7%) for evaluating the activity of phospholipase, hemolysin, proteinase, and biofilm formation were examined. The biofilm formed was analyzed by scanning electron microscopy (SEM).

Evaluation of extracellular enzymes production revealed that 86.2%, 77.6 %, and 57% of dermatophyte strains were shown to be phospholipase, hemolysin, and proteinase producers, respectively. Furthermore, all isolates of T. rubrum and M. canis can produce phospholipase and hemolysin, respectively. There was a statistically significant difference between phospholipase activity and dermatophyte strains (P<0.05). In addition, biofilm formation ability was observed in 41.5% of dermatophyte isolates. The highest level of biofilm production was found in 93% of dermatophytes isolated from nail chips. A significant difference between biofilm formation with dermatophyte isolates and different body sites was observed (P <0.05).

The activity of hydrolytic enzymes and biofilm formation as important pathogenic factors may play a role in the persistence of dermatophytosis infections. Our results showed that dermatophyte isolates have enzymatic activity and biofilm production at different levels. Therefore, understanding the function of these factors is essential to controlling the spread of dermatophytosis infection.