[Saccharomyces-induced hypersensitivity pneumonitis in a dairy farmer: a case report].

A 58-year-old man, a dairy farmer, was admitted to Engaru Kosei Hospital because of cough, fever and dyspnea following repeated exposure to moldy silage in a silo. Chest radiography showed ground-glass opacity and tiny nodules in both lung fields. Arterial blood gas analysis showed severe hypoxia (PaO2, 30.8 torr). The patient was referred to Asahikawa Medical College Hospital for a diagnostic evaluation. At the time of admission, his symptoms were slightly resolved and the lung density on the chest radiograph was decreased. Pulmonary function tests revealed restrictive ventilatory impairment with a reduction in diffusing capacity. Bronchoscopic examination revealed mild lymphocytosis in the bronchoalveolar lavage fluid (BALF). Neither bacteria nor fungi were cultured from the BALF. Transbronchial lung biopsy specimens showed alveolitis with lymphocyte infiltration. The symptoms and signs disappeared spontaneously without any specific treatment, such as corticosteroids or antibiotics. A provocation test consisting of silage handling elicited recurrence of his symptoms, a decrease in diffusing capacity, and hypoxia. A definitive diagnosis of hypersensitivity pneumonitis (HP) was made from these findings. Samplings from the silage revealed a gross growth of the yeast Saccharomyces cerevisiae. A serum-precipitating antibody gave a positive reaction for an extract of S. cerevisiae. These results suggested that repetitive exposure to S. cerevisiae had led to sensitization through the patient's occupational environment, resulting in the development of HP.