Pulmonary nocardiosis: risk factors and outcomes

Pulmonary nocardiosis (PN) is an infrequent but severe infection caused by Nocardia spp., which can behave either as opportunistic or primary pathogens. The present study identifies the risk factors for PN, clinical symptoms and radiographic features and the factors that affect its prognosis.

An observational study of all the patients diagnosed with PN over a 13-year period at the authors' institution.

Thirty-one adult patients were identified with PN, 11 of whom had disseminated nocardiosis. The predisposing conditions were COPD (23%), transplantation (29%), HIV infection (19%), alcoholism (6.5%) and treatment with steroids (64.5%). Respiratory tract sampling using non-invasive techniques had a diagnostic yield of 77%, while specimens from invasive methods had a yield of 47%. Mean time to diagnosis was 42 days. Dissemination to the central nervous system was related to alcoholism. The mortality rates were 41% for PN and 64% for disseminated nocardiosis; when Nocardia disseminated to the central nervous system, the mortality was 100%.

Specific risk factors were found in 94% of patients, with the most common being corticosteroid treatment and immunosuppressive therapy. The time to reach diagnosis and to prescribe specific treatment was considerable and mandatory assessment for nocardia in high-risk patients is required. The mortality rate of PN is high and early diagnosis and treatment are needed. Medications other than co-trimoxazole may be required.