Two episodes of cutaneous non-tuberculous mycobacterial infection in a patient with psoriasis

Non-tuberculous mycobacteria (NTM) are a group of environmental pathogens, which cause a broad spectrum of disease. The incidence of NTM infection is increasing, especially in immunocompromized patients. The past three decades also saw a rapid increase in the incidence of NTM infection involving otherwise healthy subjects. We report a case of cutaneous NTM infection in a 79-year-old Chinese woman, who was receiving methotrexate for psoriasis. Mycobacterial culture grew Mycobacterium abscessus, and the lesions cleared with a combination of oral clarithromycin, ciprofloxacin and doxycycline. Interestingly, she then developed a second episode of cutaneous NTM infection with Mycobacterium haemophilum over the same body region, five years after stoppage of methotrexate. Both episodes were separated in time and involved different species, indicating that they were independent from each other. We further discuss the risk factors for cutaneous NTM infection, treatment, and highlight the need for diagnostic vigilance.