Clinical significance of nontuberculous mycobacteria isolated from respiratory specimens / 대한내과학회지

ABSTRACT

BACKGROUND: We studied the clinical significance of nontuberculous mycobacteria (NTM) recovered from respiratory specimens for six months in a tertiary referral center. METHODS: We identified all NTM isolates from sputum or bronchial washing from October, 2001 to March, 2002, using polymerase chain reaction-restriction fragment length polymorphism analysis method amplifying the rpoB gene. Patients were classified as having definite, probable, or unlikely NTM disease as defined by the American Thoracic Society and the British Thoracic Society guidelines. RESULTS: 261 isolates of NTM recovered from 162 patients. In 162 patients, M. avium complex (MAC) was the most common species comprising 29.6% (n=48), which was followed by M. fortuitum complex (n=46, 28.4%), M. abscessus (n=26, 16.0%). 29 (17.9%) patients had definite NTM disease, and 13 (8.0%) had probable NTM disease. The common organisms involved in NTM diseases were MAC (n=23, 54.8%), M. abscessus (n=12, 28.6%). In a univariate analysis, predictive factors that were related to NTM disease were BMI <18.5 kg/m2, presence of symptoms, previous history of antituberculous treatment, positive sputum smear, presence of infiltrative, nodular or cavitary lesions at chest radiography, and isolation of MAC or M. abscessus. In a multivariate analysis, isolation of MAC or M. abscessus (OR 16.3, 95% CI 4.2~62.7, p<0.001), cavity at chest radiography (OR 4.8, 95% CI 1.4~16.6, p=0.012), and positive sputum smear (OR 4.3, 95% CI 1.4~13.3, p=0.012) were found to be variables independently associated with pulmonary disease. CONCLSUION Epidemiology of NTM pulmonary disease in Korea is different from that in other countries. A high index of clinical suspicion as well as an accurate identification of the isolates would be required for the diagnosis of NTM pulmonary disease.