Clinical significance of nontuberculous mycobacteria isolated from respiratory specimens in Korea

Polymorphisms of interferon-gamma and interferon-gamma receptor 1 genes and non-tuberculous mycobacterial lung diseases

Interferon-gamma (IFN-gamma) is crucial for host defense against mycobacterial infections. Recent studies have indicated that IFN-gamma and IFN-gamma receptor 1 (IFN-gammaR1) gene polymorphisms are associated with susceptibility to pulmonary tuberculosis. The aim of this study was to test the hypothesis that IFN-gamma and IFN-gammaR1 gene polymorphisms influence susceptibility to lung disease caused by non-tuberculous mycobacteria (NTM). Seventy-six patients with the nodular bronchiectatic form of NTM lung disease (37 patients with Mycobacterium avium complex infection and 39 patients with Mycobacterium abscessus infection) and 80 controls were included. Polymorphisms of the IFN-gamma gene at position +874 were determined by the amplification refractory mutation system (ARMS) polymerase chain reaction assay and IFN-gammaR1 gene at positions -611, -270, -56 and +95 was genotyped by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry using genomic DNA. IFN-gammaR1 -270 and +95 polymorphisms were not present in any of the patients or controls. The patients with NTM lung disease showed no significant difference from controls in genotype and allele frequencies of the IFN-gamma +874 and IFN-gammaR1 -611 and -56 polymorphisms. The IFN-gamma +874 and IFN-gammaR1 -611 and -56 polymorphisms do not appear to be responsible for host susceptibility to NTM lung disease, at least in the Korean population.

Solitary pulmonary nodule due to Mycobacterium intracellulare: the first case in Korea

Here, we describe a case of a solitary pulmonary nodule due to Mycobacterium intracellulare infection. To the best of our knowledge, this is the first case reported in Korea. A 45-year- old female, exhibiting no respiratory symptoms, was admitted to our hospital due to the appearance of a solitary pulmonary nodule on a chest radiograph. Computed tomography revealed a 2.5 cm nodule with an irregular shape and some marginal spiculation in the right upper lobe. Positron emission tomography with fluorodeoxyglucose imaging revealed positive tumor uptake (maximum standardized uptake value=8.8). Bronchoscopy yielded no specific histological findings and no bacteriological findings. Percutaneous transthoracic lung biopsy revealed epithelioid granuloma but no acid-fast bacilli were detected. The patient received isoniazid, rifampin, ethambutol, and pyrazinamide for the treatment of "tuberculoma". Five weeks after the patient was admitted, numerous mycobacterial colonies were detected on a bronchial washing fluid culture. These colonies were subsequently identified as Mycobacterium intracellulare. A final diagnosis of M. intracellulare pulmonary disease was made, and the patient's treatment regimen was changed to a combination therapy consisting of clarithromycin, rifampin, and ethambutol.

Acute pneumonia and empyema caused by Mycobacterium intracellulare

Nontuberculous mycobacterial infection is rarely accompanied by pleural involvement. We report a very rare case of M. intracellulare pulmonary disease with pleural empyema. A 56-year-old man was admitted to our hospital because of fever, purulent sputum and pleuritic chest pain. A chest radiograph and CT revealed pneumonic consolidation in the left lower lobe and loculated hydropneumothorax. The sputum smear was positive for acid fast bacilli. The aspirated pleural fluid was grossly purulent and the smear of the pleural effusion was also positive for acid fast bacilli. M. intracellulare was identified by culture and PCR from sputum and pleural fluid specimens. The patient improved with percutaneous tube drainage of the purulent effusion and antibiotic treatment including clarithromycin, rifampicin, ethambutol and streptomycin.

Mycobacterium abscessus pulmonary infection presenting as a solitary pulmonary nodule

Nontuberculous mycobacterial pulmonary infection is a rare cause of a solitary pulmonary nodule. All previously reported cases were caused by Mycobacterium avium complex, and a solitary pulmonary nodule caused by other NTM species has been very rarely reported. We describe the first case of Mycobacterium abscessus infection presenting as a solitary pulmonary nodule in a 51-year-old asymptomatic adult patient.

Diagnosis and treatment of nontuberculous mycobacterial pulmonary diseases: a Korean perspective

The incidence of pulmonary disease caused by nontuberculous mycobacteria (NTM) appears to be increasing worldwide. In Korea, M. avium complex and M. abscessus account for most of the pathogens encountered, whilst M. kansasii is a relatively uncommon cause of NTM pulmonary diseases. NTM pulmonary disease is highly complex in terms of its clinical presentation and management. Because its clinical features are indistinguishable from those of pulmonary tuberculosis and NTMs are ubiquitous in the environment, the isolation and identification of causative organisms are mandatory for diagnosis, and some specific diagnostic criteria have been proposed. The treatment of NTM pulmonary disease depends on the infecting species, but decisions concerning the institution of treatment are never easy. Treatment requires the use of multiple drugs for 18 to 24 months. Thus, treatment is expensive, often has significant side effects, and is frequently not curative. Therefore, clinicians should be confident that there is sufficient pathology to warrant prolonged, multidrug treatment regimens. In all of the situations, outcomes can be best optimized only when clinicians, radiologists, and laboratories work cooperatively.