Increasing Recovery of Nontuberculous Mycobacteria from Respiratory Specimens over a 10-Year Period in a Tertiary Referral Hospital in South Korea

Tuberc Respir Dis (Seoul). 2013 Nov;75(5):199-204. doi: 10.4046/trd.2013.75.5.199. Epub 2013 Nov 29.


Background: The number of patients with pulmonary disease caused by nontuberculous mycobacteria (NTM) has been increasing worldwide. The aim of this study was to evaluate long-term trends in the NTM recovery rate from respiratory specimens over a 10-year period in a tertiary referral hospital in South Korea.

Methods: We retrospectively reviewed the records of mycobacterial cultures of respiratory specimens at Samsung Medical Center from January 2001 to December 2011.

Results: During the study period, 32,841 respiratory specimens from 10,563 patients were found to be culture-positive for mycobacteria. These included 12,619 (38%) Mycobacterium tuberculosis and 20,222 (62%) NTM isolates. The proportion of NTM among all positive mycobacterial cultures increased from 43% (548/1,283) in 2001 to 70% (3,341/4,800) in 2011 (p<0.001, test for trend). The recovery rate of NTM isolates from acid-fast bacilli smear-positive specimens increased from 9% (38/417) in 2001 to 64% (1,284/1,997) in 2011 (p<0.001, test for trend). The proportion of positive liquid cultures was higher for NTM than for M. tuberculosis (p<0.001). The most frequently isolated NTM were Mycobacterium avium-intracellulare complex (53%) and Mycobacterium abscessus-massiliense complex (25%).

Conclusion: The recovery rate of NTM from respiratory specimens in South Korea has increased steadily.

Keywords: Epidemiology; Korea; Mycobacterium tuberculosis; Nontuberculous Mycobacteria.