Mycobacterium xenopi pneumonia in the southeastern United States.

Mycobacterium xenopi (M. xenopi) is a slow-growing, nontuberculous mycobacterium (NTM). This organism is found in fresh water and has been isolated in water samples collected from water systems in homes and hospitals. Before the acquired immunodeficiency syndrome epidemic, M. xenopi infection was infrequent and occurred in clusters; however, M. xenopi is now a recognized cause of pulmonary infection in immunocompetent patients with preexisting lung disease. The classic chest x-ray appearance is cavitary apical pulmonary disease, which mimics tuberculosis. M. xenopi is currently one of the most common NTM pathogens in parts of England and Canada and has been reported in parts of the northeastern United States. Whether the isolation of M. xenopi from our patient in Tennessee represents a new geographic distribution of this organism or technologic advancements that now allow for reliable identification is debatable. This case serves as a reminder to clinicians that the incidence of NTM infection is rising in the United States and that unusual NTM are capable of causing disease even in patients who are not immunocompromised.