Abstract
Case Report
A 65-year-old male was admitted with a two-year history of progressively increasing morning cough. His medical history included atrial fibrillation and hypertension for the past three years. He had not traveled overseas. Physical examination was unremarkable. A chest radiograph showed a tumorous shadow in the right upper field. A contrast-enhanced computed tomography (CT) scan of the chest revealed a 23×23×20-mm nodule in the right upper lobe with pleural indentation and internal necrosis (Fig. 1A). F18Fluorodeoxyglucose positron emission tomography (PET) showed active uptake (standardized uptake value [SUV] max=8.40) in the right upper lobe (Fig. 1B). Bronchoscopic examination and CT-guided needle biopsy did not yield a definitive diagnosis.
Images of infection. (
The patient underwent video-assisted tumor and partial resection of the parietal pleura because the tumor-like lesion had attached strongly to the pleura, which was difficult to distinguish from invasion. Intraoperative fast pathologic examination of the resected material confirmed the diagnosis of inflammatory phlegmon from suspected infection and ruled out neoplasm. Histologically, the man had an inflammatory focus. There were gram-positive bacilli in the lesion, and Nocardia was diagnosed by Grocott stain. Analysis of the 16S rRNA gene sequence at the Research Center for Pathologic Fungi and Microbial Toxicoses, Chiba University, Japan, confirmed that this strain was N. beijingenesis (3130×1 genetic sequencers; Applied Biosystems). The patient made an uneventful recovery, and no recurrence was detected one year later.
Discussion
Nocardiosis is a rare bacterial infection with a wide variety of clinical manifestations in immunosuppressed patients. Nocardia are found worldwide in soil that is rich in organic matter, and in total, there are 85 species. Most pulmonary infections are caused by the N. asteroids group. Nocardiosis is a potentially life-threatening infection caused by several species of the genus Nocardia such as the N. asteroids group, including N. asteroids sensu stricto, N. farcinica, and N. nova. Nocardia beijingenesis was first reported as a pathogenic bacterium for human beings in Thailand and Japan in 2004 [2].
Nocardia beijingenesis is a rare pathogen but an important bacterium categorized as an opportunistic pathogen. To our best knowledge, the present case is the fourth report of human infection and the first surgical report. The first reported case was a 70-year-old Japanese male with lung nocardiosis and no history of immunosuppressive agent therapy, but clinical data were not reported in detail [2]. The second case was a 13-year-old female with systemic lupus erythematosus in Hong Kong [3]. The CT scan of the chest showed patchy ground-glass attenuation in both lungs, and massive left lower lobe consolidation and a cavitatory lesion. The third case was a 60-year-old female in Japan with a lung infection who was treated with a corticosteroid for interstitial pneumonia [4]. Her sputum showed N. beijingenesis and Aspergillus fumigatus. The CT scan of the chest revealed bilateral diffuse interstitial shadows and multiple cavitary lesions in the left upper lobe. The present case had CT and PET findings similar to those of lung cancer, and the patient underwent lung mass excision.
Traditional treatment for pulmonary nocardiosis is an antibiotic, with a sulfonamide (trimethoprim-sulfamethoxazole) being the most common choice. High-dose imipenem-cilastatin and amikacin have been used in severe or refractory cases. The second reported case of N. beijingenesis infection was treated successfully with meropenem for four weeks, followed by cotrimoxazole for one year; and the third patient was treated with imipenem-cilastatin followed by ceftriaxone and oral minocycline. Antibiotic therapy usually is continued for more than six months, especially in immunosuppressed patients. Surgical treatment can be acceptable if the pulmonary lesion is limited and the host is not in an immunosuppressed state, as in the present case.