Familial hypersensitivity pneumonitis induced by Bacillus subtilis.

Six members of one family developed symptoms consistent with hypersensitivity pneumonitis after exposure to wood dust generated during the remodeling of a bathroom in their house. A detailed microbiologic investigation of the house and surrounding areas resulted in the isolation of 2-Bacillus species. The vegetative cell and spore extracts of these organisms were used for extensive in vivo and in vitro laboratory tests. All symtomatic members of the family demonstrated positive bronchoprovocation responses to vegetative cell extracts of B. subtilis. Two patients with clinical disease exhibited immediate positive skin tests to similar extracts. Positive lymphoproliferative responses to the vegetative cell extract of B. subtilis were observed in 4 of 5 symptomatic patients and in 1 additional patient tested with the spore form of B. subtilis. It is postulated that the abrupt appearance of this family epidemic depended on the special circumstance of continued exposure to high concentrations of B. subtilis organisms within the household. B. subtilis should be added to the list of antigens causing hypersensitivity penumonitis. Prompt recognition and elimination of this new causal agent could prevent irreversible lung damage in susceptible patients.