Nocardia transvalensis pulmonary infection in an immunocompetent patient with radiographic findings consistent with nontuberculous mycobacterial infections

A chest roentgenogram of a 75-year-old immunocompetent woman showed disseminated micronodular densities in bilateral lung fields. Subsequent high-resolution computed tomography (CT) confirmed centrilobular micronodular densities associated with bronchial wall thickening and bronchiectatic changes. CT imaging also revealed volume loss with bronchiectatic changes in both the right middle lobe and the left lingular segment. Cytology specimens were then obtained through bronchial brushing and washes. Smears from right B2 and B4 revealed filamentous gram-positive, branched bacteria embedded among many neutrophils. Nocardia transvalensis was cultured from the bronchial wash, and no mycobacteria were identified. To our knowledge, this is the first report of a Nocardia transvalensis pulmonary infection in an immunocompetent patient, and also the first detailed description of a Nocardia transvalensis pulmonary infection in Japan. Moreover, the radiographic and CT findings in this patient were quite similar to those seen in patients with nontuberculous mycobacterial pulmonary infections, a pattern not previously reported in patients with Nocardia pulmonary infections.