Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 38 3 2009 09 15 46 53 F Zaini M Mahmoudi ASA Mehbod P Kordbacheh M Safara 2015 10 03 Background: Onychomycosis results from invasion of the nail plate by dermatophytes, yeasts or mould species of fungi. The objective was to determine the etiological agents of onychomycosis. Methods: A total of 549 patients clinically suspected of onychomycosis were examined for causative fungal agents. Both di­rect microscopy and the cultures of the nail material were performed to identify the causative agents between 2004-2005 in Tehran, Iran. Results: Out of 549 cases examined, 263(47.9%) were mycologically proven cases of onychomycosis (139 finger, 124 toe nails), among those 33(6.09%) were only positive in direct microscopic examination. From an etiological point of view, 21.85% of nail infections were caused by yeasts, 10.55% were infected by dermatophytes and 15.5% by non-dermatopyte moulds. Candida albicans was the common yeast causative agent (16.73%) followed by A. flavus (11.78%), T. mentagro­phytes (10.26%), C. parapilosis (9.12%), C. tropicalis (8.74%), A. fumigatus (6.08%), T. rubrum (4.94%), A. niger (3.04%), Peni­cillium spp. (2.66%), Aspergillus spp (1.90%), each of Rhizopus spp and Cladosporium spp (1.52%), C. guilliermondii (1.14%), Sco­po­lariopsis spp. (1.14%), each of C. famata, C. glabrata, C. krusei, S. lusitania, Acremonium spp. (0.76%) and C. homicola (0.38%), T. rubrum (4.94%). Candida species were most common responsible agent for onychomycosis in fe­male hands (74.1%) fol­lowed by 17.26% non-dermatophyte moulds. Dermatophytes caused tinea unguim of hand (8.63%) and peduum (37.1%) in males. Onychomycosis of finger nails was most prevalent in females while toenail infection was com­mon in male patients. Conclusion: The yeasts of the Genus Candida and non-dermatophyte moulds are dominant cause of female finger nail onychomy­cosis and dermathophytes are principal cause of both finger and toe nails in males in Tehran. https://ijph.tums.ac.ir/index.php/ijph/article/view/3170 https://ijph.tums.ac.ir/index.php/ijph/article/download/3170/2969