Onychomycosis is usually caused by dermatophytes, but some nondermatophytic molds and yeasts are also associated with invasion of nails. The genus Chaetomium is a dematiaceous nondermatophytic mold found in soil and plant debris as a saprophytic fungus. We report the first Korean case of onychomycosis caused by Chaetomium globosum in a 35-year-old male. The patient showed brownish-yellow discoloration and subungual hyperkeratosis on the right toenails (1st and 5th) and left toenails (1st and 4th). Direct microscopic examination of scraping on the potassium hydroxide preparation revealed septate hyphae and repeated cultures on Sabouraud's dextrose agar (SDA) without cycloheximide slants showed the same fast-growing colonies, which were initially velvety white then turned to dark gray to brown. However, there was no growth of colony on SDA with cycloheximide slants. Brown-colored septated hyphae, perithecia and ascospores were shown in the slide culture. The DNA sequence of internal transcribed spacer region of the clinical sample was a 100% match to that of C. globosum strain ATCC 6205 (GenBank accession number EF524036.1). We confirmed C. globosum by KOH mount, colony, and light microscopic morphology and DNA sequence analysis. The patient was treated with 250 mg oral terbinafine daily and topical amorolfine 5% nail lacquer for 3 months.

Onychomycosis is usually caused by dermatophytes, but some nondermatophytic molds and yeasts are also associated with invasion of nails. Scopulariopsis brevicaulis is a nondermatophytic mold found in soil as a saprophyte. We report two cases of onychomycosis caused by S. brevicaulis in a 48-year-old male and a 79-year-old female. The two patients presented with a typical distal and lateral subungual onychomycosis. Direct microscopic examination of the potassium hydroxide preparation revealed fungal elements. From toenail lesions of the patients, brown colonies with powdery surface, which are a characteristic of S. brevicaulis, were cultured on two Sabouraud's dextrose agar plates. Three cultures taken from nail plates within a 2-week interval yielded similar findings. Numerous branched conidiophores with chains of rough walled, lemon-shaped conidia were observed in slide culture by light microscopy and scanning electron microscopy. The nucleotide sequences of the internal transcribed spacer for the two clinical isolates were identical to that of S. brevicaulis strain WM 04.498. To date, a total of 13 cases of S. brevicaulis onychomycosis including the two present cases have been reported in Korea. Mean age of the patients was 46.1 years, with a higher prevalence in males (69.2%). Toenail involvement was observed in all cases including a case involving both fingernail and toenail. The most frequent clinical presentation was distal and lateral subungual onychomycosis in 12 cases, while one case was proximal subungual onychomycosis.