A case of onychomycosis due to Aspergillus sydowii diagnosed using DNA sequence analysis

We report a case of disto-lateral subungal onychomycosis of the first toe of the right foot of a 33-year-old female. The causative agent was identified as Aspergillus sydowii based on DNA sequencing and the macroscopic and microscopic characteristics of the culture. Initially, the medial one-third of the right first toenail was streaked with numerous yellow longitudinal stripes that had fused, with no symptoms of tinea pedis. Treatment with oral terbinafine and itraconazole was ineffective. Based on this case and on three other cases in the literature, the clinical characteristics of onychomycosis caused by A. sydowii can be summarized as follows: (i) no clinical history of symptoms of tinea pedis; (ii) lack of clinical response to oral antifungal agents; (iii) streaked and turbid appearance of the diseased nail and (iv) presence of dichotomous irregular hyphae, as detected by direct microscopic examination.