Causative Agents of Onychomycosis: A 7-Year Study

Abstract

Background: Onychomycosis is principally caused by dermatophyte species, but nondermatophyte molds and yeasts have also been involved, causing different clinical manifestations. The aim of this investigation is to determine the clinicomycological and epidemiological profile of the etiologic agents of onychomycosis.

Methods: The study population included 9,785 suspected cases of onychomycosis referred to the Medical Mycology Reference Laboratory in Isfahan, Iran, during 2007-2014. Nail clipping was collected in sterile Petri dishes for direct microscopic examination and culture. Clinical isolates were identified by using phenotypic tests and molecular techniques.

Results: Of total 9,785 cases with clinical suspicion of onychomycosis comprised in the present study, 1,284 patients (13.1%) were positive by direct microscopy. Age range of patients was between 1 and 82 years. Housewives were the commonest infected population. Candida albicans was the most prevalent species isolated from patients in this study (34.9%) followed by Trichophyton interdigitale (11.7%) and Aspergillus flavus (9.1%).

Conclusion: The pattern of causative agents and clinical signs of onychomycosis is altering region to region, so repeated epidemiological surveys of onychomycosis seems to be fundamental. The present study provides novel and appropriate epidemiologic data of onychomycosis for the better prevention and treatment of this fungal infection.

Keywords: causative agents; identification; onychomycosis.

Figure 1

Distribution of patients with onychomycosis according to their occupation.

Figure 2

(a) PCR products of various Candida species: lane 1: C. guilliermondii, lanes 2, 6, 7: C. albicans, lanes 3, 5: C. krusei, lane 4: C. tropicali, and lane M: 100 bp DNA size marker. (b) Agarose gel electrophoresis of ITS‐PCR products of Candida species after digestion with HpaII. Lane 1: C. tropicalis, lane 2: C. parapsilosis, lanes 3, 6, 9: C. albicans, lanes 4, 8: C. glabrata, lane 5: C. kefyr, lane 7: C. krusei, and lane M: 100 bp DNA size marker. (c) Agarose gel electrophoresis of SADH‐PCR products after digestion with NlaIII. Lanes 1, 2: C. parapsilosis, lane 3: C. orthopsilosis, and lane M: 100 bp DNA size marker.

Figure 3

(a) PCR products of various dermatophyte species: Lane 1: E. floccosum, lanes 2–4: T. interdigitale, lane 5: T. rubrum, lane M: 100 bp DNA size marker. (b) Electrophoretic profile of ITS‐PCR products of dermatophyte species digested with MvaI restriction enzyme. Lanes 1—3, 6: T. interdigitale, lane 4: E. floccosum, lane 5: M. canis, and lane M: 100 bp DNA size marker.

Figure 4

Fungal agents of onychomycosis between 2007 and 2014 in seven periods.