Familial cluster of cutaneous Mycobacterium avium infection resulting fromuse of a circulating, constantly heated bath water system

We describe familial cases of cutaneous infection caused by Mycobacterium a vium. A 45-year-old father, his 14-year-old son and 11-year-old daughter, a mong five persons in a family, presented with a 2-month history of inflamma tory subcutaneous nodules and ulcerations. Histology of skin biopsy specime ns showed granulomatous inflammation, and mycobacterial colonies isolated f rom the skin of each patient were identified as M. avium by DNA hybridizati on analysis. The patients were all treated successfully with combined drug therapy consisting of rifampicin, isoniazid and clarithromycin. Their lesio ns were purely cutaneous M. avium infection, without any visceral involveme nt, Neither systemic disease nor immunological impairment was detected in t he family. However, they all used a circulating, constantly heated bath wat er system. The bath water was continuously heated to about 40 degrees C wit hout changing the water for a few months, and ill. avium was isolated from the filter of the bath tub heating unit. It is considered that this unusual familial cluster of cutaneous M. avium infection in healthy persons may ha ve resulted from the use of contaminated bath water.