Prevalence and Species Spectrum of Pulmonary Nontuberculous Mycobacteria Isolates at a Tertiary Care Center

Abstract

Background: Pulmonary infection with nontuberculous mycobacteria (NTM) is increasing in South Korea. Since treatment strategy differs by NTM species, ac-curate identification is necessary. In this study, using Mycobacterium pulmonary isolates recently recovered from a general hospital in Seoul, the prevalence of NTM isolates was investigated. Methods: A total of 483 Mycobacterium pulmonary strains isolated between May and November 2018 from an 814-bed general hospital in South Korea were analyzed. Bacterial species were identified based on nucleotide sequences of the 16S-23S rDNA internal transcribed spacer and the rpoB gene. Results: From a total of 1,209 pulmonary specimens from patients suspected to be infected with mycobacteria, 324 deduplicate strains were isolated, compris-ing 90 Mycobacterium tuberculosis and 229 NTM strains. Among the NTM isolates, 61.5% (n=144) were Mycobacterium avium complex (MAC), including 92 M. avium and 52 Mycobacterium intracellulare , while 8.1% (n=19) represented Mycobacterium abscessus , including 10 M. abscessus subsp. abscessus and 9 M. abscessus subsp. massiliense . In addition, 12 (5.1%) Mycobacterium lentiflavum , 12 (5.1%) Mycobacterium gordonae , 6 (2.6%) Mycobacterium kansasii , and 5 (2.1%) Mycobacterium fortuitum were identified. In addition, Mycobacterium mucogenicum (n=2), Mycobacterium septicum (n=1), Mycobacterium colombiens (n=1), Mycobacterium asiaticum (n=1), and Mycobacterium celatum (n=1) were identified. Conclusion: Among the recently recovered Mycobacterium pulmonary strains, more than half were identified as NTM, and MAC was the most prevalent NTM, followed by M. . (Ann