[Chronic pulmonary nocardiosis with eosinophilia in an immunocompetent host]

A 75-year-old man who worked at a horse racing track, had an abnormal shadow on a chest radiography. He had a history of dilated cardiomyopathy and mitral regurgitation but had not had any respiratory or systemic symptoms for two years. Chest radiographs and CT scans showed slowly increasing consolidation with internal areas of low attenuation, and without cavity formation, at the left S8. The erythrocyte sedimentation rate, C-reactive protein level, WBC count, percentage of eosinophils, and IgE level were 35 mm/hr, negative, 8400, 17%, and 3628 IU/ml, respectively. Eosinophils were found in samples of sputum. His immunological status was normal. Transbronchial lung biopsy yielded necrotic tissue, along with gram-positive and irregular acid-fast branching filaments that grew in culture. The microorganism was identified as Nocardia asteroides. Occupational inhalation of soil may have caused his disease.