The usage of molecular methods in the diagnosis of dermatophytosis

Dermatophytes are fungi which are widespread throughout the world, and are responsible for the common disease of dermatophytosis, or ringworm. In the diagnosis of these infections by classical methods, direct microscopy can give false negatives, and species-specific diagnosis is not possible. Although fungal culture is a specific method, a long incubation period is needed for propagation, and there is often a need for supplementary tests to identify the isolates correctly. The purpose of this study was to examine the use of molecular methods in the diagnosis of dermatophytosis, and to discover whether they have any advantage over classical methods.Included in the study were 123 samples (63 skin and 60 nail) taken from 110 patients who attended Aydın State Hospital Dermatology Polyclinic between 1.3.2010 and 30.6.2010 with suspected derematophytosis and who had been sent to the Microbiology Laboratory of the same hospital. Microbiological and molecular examination of the samples was performed in the Microbiology Laboratory of the Adnan Menderes University Research and Application Hospital. Samples were directly examined microscopically with a 20% solution of potassium hydroxide, or were placed on Sabouraud dextrose agar and potato dextrose agar broths for fungal culture. Pan-dermatophyte nested PCR with primers targeting the chitin synthase 1 (CHS1) gene region, and also nested PCR with primers specific to Tricophyton rubrum and Tricophyton mentagrophytes were carried out on the strains produced in the cultures and directly on the collected samples. In samples where inconsistencies were found between PCR methods, this was resolved using identification by sequence analysis.Fungal components were seen in 62 (50.4%) of the samples, and dermatophytes were produced in 30 (24.4%) of the cultures. Identification results were found to be the same for the strains produced in the culture by classical methods as the identified by nested PCR. Pan-dermatophyte nested PCR gave positive results in 67 (54.5%) samples, and T. rubrum/T. mentagrophytes nested PCR in 65 (52.9%) samples.The agents of dermatophytosis has been fastly identified in species, with molecular diagnostic methods used in our study. It has been suggested that in the routine diagnosis of dermatophytosis, molecular methods may be appropriate diagnostic tool in laboratories.