[Acute bronchiolitis due to Mycoplasma pneumoniae and successfully treated with steroids].

A high fever, coughing, stridor, and dyspnea developed in a 52-year-old woman on October 19, 1995. She went to a local clinic and was treated with oral penicillin and intravenous cefpirome. The symptoms worsened, and she was admitted to our hospital on October 26. Coarse crackles and wheezing were heard in both lung fields. The white blood cell count was 9000/mm3 and arterial blood gas analysis revealed a PaO2 of 49.8 Torr on room air. A chest roentgenogram obtained on admission showed a few small bibasilar nodular infiltrates, and a chest CT scan showed thickened bronchial walls along with small nodules having a centrilobular distribution. Of the cells in bronchoalveolar lavage fluid, 88% were neutrophils, but tests for bacteria and mycobacteria were negative. The cold-agglutinin titer was 1:512. The Mycoplasma pneumoniae antibody titer (IIIA) was 1:640 and viral serology tests were negative. Acute bronchiolitis due to M. pneumoniae was diagnosed and treatment with intravenous minocycline was started. The symptoms (coughing, fever, and stridor) resolved and the small nodules on chest CT scan disappeared, but hypoxemia remained. At the same time, an obstructive ventilatory defect (FEV1% 62.8%) and abnormal ventilation/perfusion lung scans were noted. Development into bronchiolitis obliterans was suspected, so administration of methyl prednisolone (1 g/day for 3 days) and prednisolone was started. The response to steroids was good. Pulmonary function improved and the arterial PaO2 at the time of discharge was 86 Torr (room air). Use of steroid therapy in the early phase of bronchiolitis obliterans seemed to be effective.