Clinical and Radiographic Characteristics of Pulmonary Nocardiosis: Clues to Earlier Diagnosis

Background and objectives: Pulmonary nocardiosis (PN) is a rare but life-threatening disease that is caused by Nocardia spp. The aim of this study was to characterize the common risk factors, clinical features, imaging findings, treatment and outcomes of PN, which are useful for an early diagnosis and patient management. Methods: From January 2009 to June 2013, a retrospective study was performed on all PN cases that were diagnosed at our hospital. Results: The study included 17 patients who were diagnosed with PN. Of these patients, 4 developed concomitant disseminated disease. A male predominance was observed among the patients with PN (76.47%). The most common risk factors were corticosteroid therapy (64.71%), diabetes mellitus (29.41) and chronic lung disease (23.53%). Cough and fever were the most common symptoms (94% and 71%, respectively). One or more nodules or masses (82.35%) and consolidations (58.82%) were the most frequent radiologic abnormalities, and cavitation mostly occurred within two weeks. The median time to diagnosis was 25 days. Overall, the mortality rate was 18.75% for PN, and death was most frequent among patients who received immunosuppressive drugs. For the patients with central nervous system involvement, the mortality rate was 50%. Conclusion: PN remains a rare opportunistic infection that mainly affects immunocompromised patients. A high clinical index of suspicion is necessary for an early diagnosis and timely treatment in immunocompromised patients who present with new nodules or masses evolving into cavitation in a short amount of time.