Clinical Features of Pulmonary Nocardiosis: Experience with 30 Cases

Abstract

Nocardia is a Gram-positive aerobic bacillus that can cause localized or disseminated infection, with major transmission via the respiratory tract. In order to further understand the consequences of this bacillus, this study sought to evaluate the predisposing factors, clinical features, radiographic findings, treatment, and outcome of patients with pulmonary nocardiosis. We reviewed 30 cases of pulmonary nocardiosis diagnosed in our hospital between 1992 and 2003. All of the cases had evidence of pneumonia on the chest radiograph, and at least I airway specimen with a positive culture for Nocardia species. The mean age of the patients was 68 years, and the male to female ratio was 23:7. Many of the patients had preexisting lung illness (43.3%), such as chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis, or lung cancer. In addition, most of the patients had conditions that might impair immunity (70.0%), including long-term steroid use, hematologic or solid organ malignancy, diabetes mellitus, and other. Dyspnea, fever, and cough were the most common symptoms. The most common pattern on the chest radiographs was consolidation (80.0%). Other patterns included mass, nodules, and mixed consolidation and nodules. The mean period needed for culture was 19 days. Nocardia asteroides accounted for most of the isolated species (56.7%). Twenty patients received treatment after the diagnosis of pulmonary nocardiosis, either during hospitalization or after discharge. Most of them received trimethoprim/sulfamethoxazole (TMP/SMX). The other 10 patients, whose diagnosis of pulmonary nocardiosis was made after discharge, did not receive treatment because of death, lost to follow-up, or disease improvement on their own. Disseminated infection occurred in 2 patients only; 1 with brain abscess and the other with bacteremia. Nine patients (30%) died during hospitalization. Most of them developed early respiratory failure and septic shock, which may have contributed to mortality. In conclusion, pulmonary nocardiosis is a rare condition, but may be fatal. The diagnosis is time-consuming and not easy. However, clinicians should take pulmonary nocardiosis into the differential diagnosis of pneumonia in patients who are immunocompromised.