Increasing numbers of patients have presented with a hypersensitivity pneumonitis-type course in association with hot tub exposure. Mycobacterium avium complex (MAC) organisms have been isolated from both patient specimens and hot tub water with matching fingerprints by restricted fragment length polymorphism and electrophoresis when performed. Review of 9 patients at Mayo Clinic, Rochester are compared with 32 patients in the published literature (reference patients).
Nine patients have been diagnosed with MAC-associated hot tub lung at Mayo Clinic, Rochester. Charts were retrospectively reviewed for information regarding demographics, clinical characteristics, environmental sampling, diagnostic studies, treatment regimen, and clinical course. These data were compared to those reported in the literature.
Mayo patients (reference patients) ranged in age from 14 to 66 years ( 9 to 69) with an average age of 44 (36). Symptoms had been present for an average of 2.9 months (3.0) with a range of 2 to 6 months ( 2 to 4 ). Common signs and symptoms included dyspnea 100% (100%), cough 100% (100%), and fever 75% (52%). Hypoxemia was noted in 88% (52%). High resolution chest CT demonstrated diffuse infiltrates in 100% (70%) and nodules in 60% (13%). MAC organisms were isolated from sputum in 88% (60%) and lung tissue in 66% (100%). Histopathologic findings included nonnecrotizing granulomas in 100% (100%), necrotizing granulomas in 12% (20%), and organizing pneumonia in 12% (20%). Lymphocytes were elevated at 57% and 62% in the two bronchoalveolar lavages that were done. Treatment involved corticosteroids in 64% ( 19%), antimycobacterial therapy in 0% (26%), combined steroids and antimycobacterial therapy in 12% (39%), and no therapy in 12% (16%). All patients returned to normal lung function.
MAC organism exposure from hot tubs may result in a hypersensitivity pneumonitis-type reaction.
Clinicians should be aware of an increasing number of MAC associated hypersensitivity pneumonitis-type cases related to hot tub exposure. Whether this represents infection, inflammation, or both is a matter of debate and ongoing investigation.
T.R. Aksamit, None.