Recovery Rate of Nontuberculous Mycobacteria and the Clinical Course of Nontuberculous Mycobacterial Pulmonary Disease at a Secondary Hospital

Background: To examine the recovery rate of nontuberculous mycobacteria (N TM) from respiratory specimens and the clinical course of NTM pulmonary disease at a 700-bed secon dary hospital.Methods: This study analyzed the results of 843 acid-fast bacilli (AFB) culture-positive respiratory specimens from 650 subjects collected between May 2003 and April 2008. In addi tion, the clinical course of NTM pulmonary disease, diagnosed using criteria established by the American Thoracic Society, was examined.Results: There were 67 (7.9%) NTM isolates recovered from 52 (8.0%) sub jects. Among the 535 AFB smear-positive specimens, 34 (6.3%) NTM isolates were recovered. There were 33 (10.7%) NTM isolates were recovered from 308 AFB smear-negative specimens. Of 52 subjects with isolated NTM, M. intracellulare was the most common species at 73.1% (n=33), followed by M. kansassi (n=7), M. abscessus (n=2), M. fortuitum (n=2), and M. avium (n=1). Sixteen (30.8%) patients had NTM pulmonary disease and t he most common causative organism was M. intracellulare (n=14, 87.5%). Of these, 6 cases attained negative conversion in culture, 4 cases failed to attain negative conversion because of poor cooperation or expiration from complicated underlying lung disease, and 5 cases were transferred to a higher-grade hospital.Conclusion: The recovery rate of NTM from respiratory specimens was relati vely low and the most common species was M. intracellulare. Patients with NTM pulmonary disease showed variable clinical outcomes.Key Words: Atypical mycobacteria, Lung diseases, Patient outcomes