A Case of Cutaneous Mycobacterium chelonae Infection Diagnosed by the Colonies Yielded on Sabouraud's Medium

Abstract

An 85-year-old man with no underlying disease or prior trauma had suffered from red nodules on the back of his hand for 2 months. Culture of a skin biopsy specimen from the nodules yielded white colonies on Sabouraud's medium but not on Ogawa's medium. DNA-DNA hybridization revealed that the colonies were Mycobacterium chelonae (M. chelonae). The patient was treated with clarithromycin and levofloxacin. The erythema and nodules improved in 4 weeks and the treatment was stopped after 16 weeks. M. chelonae is a rare, rapidly-growing mycobacterium. Although most of the patients infected with this mycobacterium have prior trauma or underlying disease, its occurrence in healthy individuals has also been reported. The diagnosis of M. chelonae infection is often difficult because of the low positive rate of culture. M. chelonae colonies are most often seen on Sabouraud's medium or blood culture medium. Thus, for diagnosis, it is important to culture the samples in various media repeatedly. Currently, there is no standardized treatment regimen for M. chelonae infection. We summarized the procedure for treating cutaneous M. chelonae infection with antibiotics.