Nocardia is an aerobic, gram-positive filamentous bacteria and commonly affects respiratory system in human. Nocardia can cause disseminated disease involving central nervous system (CNS), and skin or rarely other organ (3). It can cause acute, subacute as well as chronic disease and high suspicion of index is required for diagnosis. Pulmonary Nocardiosis is consider to be an opportunistic infection and occurred mainly in patients with defective cellular immunity. Due to lack of specific clinical features, diagnosis of pulmonary nocardiosis turn out to be difficult. In most of the time pulmonary tuberculosis, lung abscess, bronchiectasis with secondary bacterial infection, invasive fungal infection etc. are keeping as initial diagnosis in patients with Pulmonary Nocardiosis. This study is focused on clinical and laboratory features in patients with pulmonary nocardiosis to increase awareness among community physician.
The mean age of patients in this study was 50 ± 14.3 years and disease was common in female. Contrary to this, previously literature had higher incidence of pulmonary nocardiosis in male (1, 4, 5, 6, 7). This difference may be due to smaller number of cases or lack of larger studies. Chronic obstructive lung disease (COPD) was the most common risk factor associated in around 40% of cases. COPD and chronic steroid use are the important pre-existing factor for Pulmonary Nocardiosis and more than half of patients had above comorbidities in previous studies (1, 2, 3, 8, 9). Patients with malignancy, leukemia, HIV, diabetes, on cytotoxic chemotherapy and organ transplant recipient are also have increased risk for Nocardiosis. Association of Idiopathic CD4 lymphocytopenia and Pulmonary Nocardiosis is less studied. In this study one patients had low CD4 (less than 300 cell/µL) on two occasion with negative for HIV-1 and 2. We recommend that CD4 count should be done in every case of Nocardiosis to find association with ICL and further prophylaxis.
The duration of disease was subacute or chronic in most of cases but one patient was presented with 6 days of illness, who also had pancytopenia. High suspicion should be kept even in acute presentation especially in patients with risk factors (3). The common presenting clinical features were cough, expectoration and breathlessness while fever was seen only in half of cases. These clinical features are non-specific and often directed towards tuberculosis or fungal infection. Invasive nature of disease is important diagnostic clue and one patient had extension of disease in chest wall, which was diagnosed in CECT thorax. Though there were no specific abnormalities seen in hematological profile. Anemia, lymphocytosis, neutrophilia and raised inflammatory markers were found similar to other cases series (1, 10). Persistent symptoms, raised inflammatory markers and lack of other infective etiology in patient with chronic lung disease become a high index of suspicion for Pulmonary Nocardiosis.
Common CT thorax findings in Pulmonary Nocardiosis were parenchymal nodules, consolidation, mediastinal lymphadenopathy with or without cavitation present in around 70% of patients. Above CT abnormality in immunocompromised patients with high clinical suspicion may suggest the likelihood of Pulmonary Nocardiosis (11). Confirmation of diagnosis is requiring identification and isolation of Nocardia spp. In modified acid‑fast staining using 1% sulfuric acid and/or culture in sputum or BAL sample (1). In this study all patients had positive for modified acid‑fast staining, showed filamentous branching bacilli consisted with Nocardia spp. BAL was done in four cases and out of them 2 had positive culture for Nocardia spp. Species identification was not done due to resource constrain. A clinical background should be taken care during isolation of Nocardia spp. to avoid over diagnosis and superfluous use of antibiotic.
These is no definitive treatment guideline for nocardiosis and most of the data are from retrospective studies. Combination antibiotic therapy with Trimethoprim‑sulfomethoxazole is, in a dose of 25–50 mg/kg per day of sulfamethoxazole is the most widely used in treatment (1, 3). Amikacin, ceftriaxone, imipenem and linezolid have been showed effectiveness in various combination. Pulmonary disease with moderate symptoms (50% cases) were treated with combination of ceftriaxone plus amikacin plus Trimethoprim‑sulfomethoxazole showed effective cure in this study. Patients should be treated for at least 6 months’ duration or till resolution of disease especially in immunocompromised patients (12). Mortality is high in nocardiosis and one long term study showed 41%, 64% and 100% mortality in pulmonary, disseminated and CNS disease respectively (2). Six patients were treated for 6 months, one patient treated for 12 months and one died during tretament in this study.