BI26 Disseminated cutaneous Mycobacterium chelonae...

Published Date: 19th July 2016

Publication Authors: Hickey S, Forsyth L

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We report a rare case of disseminated cutaneous Mycobacterium chelonae and phaeohyphomycosis occurring in an immunocompromised patient, a 67-year-old man who developed a rash while on intravenous teicoplanin for Charcot joint osteomyelitis. The rash became widespread over the course of 2 months despite discontinuation of his antibiotics. On initial examination, he was noted to have multiple pustular nodules, mainly on his arms and legs. He had a complex medical history, including bronchiectasis, and was taking daily prednisolone. Skin biopsy showed acute granulomatous dermal inflammation, and Ziehl-Neelsen stain showed many bacilli. Polymerase chain reaction for atypical mycobacterium was negative. In December 2012 he was commenced on clarithromycin 500 mg twice daily for suspected atypical mycobacterium, and the lesions on his legs started to clear. In March 2013, he presented with a distinct black verrucous lesion on his right index finger, which was biopsied. Histology showed large numbers of fungal spores and plump budding hyphae of the phaeohyphomycosis group. Exophiala was subsequently isolated in culture, and posaconazole 400 mg twice daily was initiated. Coincidentally, at the same time, he relapsed with more pustular nodules, which were similar to his original rash. A swab taken from one of the lesions cultured mycobacteria, speciated as Mycobacteria chelonae. Ciprofloxacin 500 mg twice daily was added to his antibiotic regime. Mycobacterium chelonae is a rapidly growing atypical mycobacterium. It usually causes clinical disease in penetrated wounds or in patients who are immunosuppressed, on corticosteroid therapy, have renal failure or haematological malignancy. Phaeohyphomycosis are a group of dematiaceous fungi; the tissue morphology of the organism is mycelial. The melanin in their cell wall is thought to act as a virulence factor. These organisms are ubiquitous, but found mainly in soil, wood and decaying plant matter. Our patient had phaeohyphomycosis of Exophiala species. Most reported cases of infections due to Exophiala species are in immunocompromised patients. Treatment is determined by definitive species identification and sensitivity to antifungal agents. Newer antifungals, such as variconazole, posaconazole and ravuconazole, have demonstrated a broader spectrum of activity and therefore appear promising in improving the therapy to treat these infections in the future (Revankar SG, Patterson JE, Sutton DA et al. Disseminated phaeohyphomycosis: review of an emerging mycosis. Clin Infect Dis 2002; 34: 467-76).

Meah, N; Hickey, S; Chaponda, M; Forsyth, L; Hope, W. (2014).  BI26 Disseminated cutaneous Mycobacterium chelonae and phaeohyphomycosis . British Journal of Dermatology. 171 (Supplement S1), 112

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