Disinfection and monitoring of Mycobacterium avium complex in the environment: A novel approach to the management of hot tub lung.

A 45-year-old man visited our hospital with a chronic cough and breathing difficulties. Chest computed tomography revealed diffuse granular shadows. Mycobacterium avium (M. avium) was cultured from bronchoalveolar lavage fluid (BALF). Surgical lung biopsy revealed non-necrotizing granulomas, and M. avium-specific PCR was positive in the tissue. M. avium was also cultured in a sample from the inlet of the patient's bathtub. Mycobacterium avium tandem repeat variable-number tandem-repeat loci (MATR-VNTR) analysis confirmed that the M. avium cultured from BALF and the bathtub inlet had identical allele profiles. The patient's symptoms and oxygenation improved while the patient was in hospital, presumably because of lack of ongoing exposure to M. avium. He was diagnosed with hot tub lung. We advised the patient to avoid bathing to avoid re-exposure. However, the patient was unwilling to follow this advice. Therefore, his bathtub and pipework were disinfected by heating them to over 70 °C. We confirmed that the disinfection has been successful by repeated culture of environmental samples. Three months after resuming bathtub use, the patient's symptoms resolved, and the pulmonary shadows seen on the initial radiography did not recur. For the treatment of hot tub lung, disinfection of M. avium complex in the environment should be considered and the environment should be monitored to confirm eradication.