High prevalence of superficial white onychomycosis by Trichophyton interdigitale in a Japanese nursing home with a geriatric hospital.

ABSTRACT

A mycological survey on feet was performed in a nursing home with a geriatric hospital to ascertain the prevalence of tinea lesions. Of 100 subjects, comprising 62 in the nursing home and 38 in the geriatric wing, 70 were diagnosed with tinea pedis, tinea unguium (onychomycosis) or both of which 54 had onychomycosis alone, nine tinea pedis alone and seven had co-existing onychomycosis and tinea pedis. The most common clinical type of onychomycosis was distal lateral subungual onychomycosis (DLSO) at 30 cases, followed by superficial white onychomycosis (SWO) at 23 cases. Fifteen strains of Trichophyton (T.) interdigitale isolated from 23 SWO patients comprised six molecular types (D2II, nine cases; C2II, two cases; four other types, one case of each), based on the non-transcribed spacer region (NTS) of the ribosomal DNA. The pathogen of three other SWO cases was identified as T. rubrum. Direct physical contact between the subjects was unlikely because they were bedridden most of the time. Nine T. interdigitale strains were isolated from a bathtub used by patients on the floor with a high incidence of SWO alone, and all nine strains were D2II type, which suggests nosocomial infection. Consequently, the hospital infection control policy committee was consulted, bathing arrangements were changed, and nursing staff were educated about onychomycosis.