Hypersensitivity pneumonitis secondary to Klebsiella oxytoca. A new cause of humidifier lung.

A 30-year-old woman developed recurrent episodes of fever, dyspnea, and nonproductive cough after repeated exposure to a home humidifier. The diagnosis of hypersensitivity pneumonitis was confirmed by detection of serum-binding antibodies at significant titer to Klebsiella oxytoca colonizing the humidifier water but not to other potential antigens. This represents a newly recognized cause of hypersensitivity pneumonitis related to exposure to K oxytoca contaminating a commercially available ultrasonic cold air home humidifier. The potential role for these frequently used home humidifier devices in unexplained pulmonary illness is emphasized.