Cutaneous Mycobacterium immunogenum infection in an immunocompetent individual

Objective Skin and soft tissue infections caused by rapidly growing nontuberculous mycobacteria have become an increasing clinical problem. Here, we confirm a rare case of cutaneous infection caused byMycobacterium immunogenum from histology and genetics.Methods A biopsy was taken for histological examination and tissue culture. Organisms that grew in L?wenstein-Jensen medium were identified by polymerase chain reaction and sequencing ofhsp65 and 16S rRNA genes.In vitro drug susceptibility testing was conducted using the microtiter plate method.Results The tissue culture was mycobacteria-positive. Analysis ofhsp65 and 16S rRNA genes confirmed that the organism isolated wasMycobacterium immunogenum. Systemic therapy for the patient was based on thein vitro drug susceptibility results. It involved 6 months of clarithromycin (0.5 g twice per day) and moxifloxacin (0.4 g once per night) combined with 6 months clarithromycin tapering (0.25 g once per day), and completely resolved the skin lesions, leaving only residual scaring.Conclusion Mycobacterium immunogenum, an environmental organism, has emerged as an infection-causing pathogen of immunocompetent individuals.