Background: Nocardiosis is a rare but potentially severe infection that can affect the immunocompromised as well as the immunocompetent population. It presents as a localized or disseminated infection, most commonly introduced through the respiratory trac. A significant amount of time is often needed to establish a diagnosis of nocardiosis, which has been reported to be as long as 6 weeks. Hence, more description of the clinical and radiological characteristics is needed as clues to early diagnosis and management. This study is aimed to retrospectively review the clinical and radiographic features and outcomes of the cases of pulmonary nocardiosis over the past 10 years at a tertiary medical center.
Methods: A computerized database search was conducted to identify all culture-proven cases of nocardiosis from John H. Stroger Jr. Hospital of Cook County from 07/01/2007 to 07/01/2017. Pulmonary nocardiosis was defined by the isolation of Nocardia from a respiratory sample in addition to respiratory symptoms and/or radiographic infiltrates. The disseminated disease was defined by the isolation of Nocardia from the bloodstream or from two or more organs. Analysis of the data was done using descriptive statistics.
Results: 20 Patients (11 male, 9 female) were diagnosed with pulmonary nocardiosis in the studied period. The average age was 55±14.5 years. In these patients, 2 developed concomitant disseminated disease. 11/20 patients had underlying pulmonary diseases at the time of diagnosis, the most common ones are healed or active pulmonary mycobacterial infection (7/20), chronic obstructive pulmonary disease (4/20) and aspergilloma (2/20). 12/20 patients were immunocompromised due to various systemic diseases, such as chemotherapy (5/20) , diabetes mellitus(4/20) or HIV (2/20). Cough, dyspnea and chest pain were the most common symptoms (16/20, 9/20, 9/20 respectively). One or more pulmonary nodules or masses (13/20), bronchiectasis(8/20) and hilar or mediastinal lymphadenopathy(7/20) were the most frequent radiologic abnormality. 7/20 patient received sulfamethoxazole/trimethoprim as first-line therapy. The median time to initiating therapy was 26 days. Overall, the 60-day mortality rate was 3/20.
Conclusions: Our study suggested that the high-risk population of pulmonary nocardiosis include the immunocompromised, as well as those who have underlying lung abnormalities such as mycobacterial infection, COPD or aspergilloma. Gender predominance was not demonstrated. In our study, the most common symptoms were cough, respiratory distress, and chest pain. Pulmonary nodules or masses, bronchiectasis and lymphadenopathy were the most frequently seen radiological findings. The microbiological diagnosis was often delayed, thus, a high clinical suspicion is necessary for patients with these risk factors and manifestations to achieve early diagnosis and management.