A Clinicomycologic Study of Dermatophytosis of the External Auditory Meatus / 대한피부과학회지

ABSTRACT

BACKGROUND: Otomycosis is a mycotic disease of the external auditory meatus. Aspergillus is the most common pathogen. Despite the fact that a great number of fungi are considered as the cause of otomycosis, otomycosis due to dermatophytes occurs with great rarity. OBJECTIVE: The purpose of this study was to investigate clinical and mycological features of dermatophytosis in the external auditory meatus. METHODS: We performed a clinical and mycologic analysis of 17 patients who had been clinically and mycologically diagnosed with dermatophytosis of the external auditory meatus. In addition, amplication of TRS-1 and TRS-2 of the ribosomal DNA nontranscribed spacer was performed on strains of Trichophyton (T.) rubrum and T. raubitshcekii which were isolated from skin lesions of the external ear and cerumen in 6 patients. RESULTS: The ratio of male to female patients was 1.41. The age of patients were 6 to 72 and mean age of onset is 36.4. Eleven patients had concomitant dermatophytosis of other sites. Tinea unguium was combined in 7 cases, tinea pedis in 4 cases, tinea corporis in 3 cases, tinea manus in 2 cases and tinea cruris in 1 case. The positive rate of KOH examination was 88.2% and the positive rate of fungal culture on PDAC media was 88.2%. The most common organism cultured was T. rubrum (80.0%), followed by T. raubitschekii (13.3%) and T. mentagrophytes (7.7%). Ten patients were treated with topical terbinafine and seven patients with oral itraconazole, so all patients were cleared of fungi from the external auditory meatus and inflammation was resolved. With TRS-1 and TRS-2 amplication, 4 of 5 pairs of T. rubrum and 3 strains of T. raubitshcekii showed the same types regardless of the site in each patient. CONCLUSION: Dermatophytosis occurs rarely in the external auditory meatus but we experienced 17 cases of dermatophytosis at this site. With suspected otomycosis, dermatophytosis of the external auditory meatus and concomitant dermatophytosis must be investigated and treated simultaneously to prevent any recurrence.