One of a rapid growing mycobacteria (RGM), Mycobacterium abscessus (MAB), is the most causative agents of RGM pulmonary disease. MAB can change their morphology that smooth (S) type to more virulent type of rough (R). Bacterial invasion into host cells is an important first step to initiate their infection. The phagocytic and invasion mechanisms of Mycobacterium tuberculosis through the host-parasite interaction have been researched. Although MAB causes a wide range of clinical diseases, little is known about their invasion ability or why the R type is more virulent than the S type. To compare invasion ability of R with S types, their infection abilities to dermal fibroblast, HaCaT cells, A549 cells and bone marrow derived macrophages were analyzed. After 2 h of infection, intracellular survival numbers of the R type were significantly higher in all infected cells than S types. The fluorescence-activated cell sorting (FACS) and confocal microscopy assay also revealed that red fluorescent amount and intracellular bacterial numbers in all of the cells infected with MAB R type expressing the red fluorescent protein (RFP) were significantly higher than the S type. Our data suggest that the virulence of MAB is proportionally related to the invasion ability into mammalian cells and macrophages.
Fibroblasts ; Flow Cytometry ; Host-Parasite Interactions ; Infection ; Lung Diseases ; Macrophages ; Microscopy, Confocal ; Mycobacterium tuberculosis ; Mycobacterium* ; Virulence

BACKGROUND: The burden of nontuberculous mycobacterial (NTM) pulmonary disease (PD) is increasing globally. To understand the treatment outcomes and prognosis of NTM-PD, a unified registry is needed. In this project, we aim to construct a multicenter prospective observational cohort with NTM-PD in South Korea (NTM-KOREA).METHODS: The primary objective of this study is to analyze treatment outcomes according to the species. In addition, recurrence rate, adverse events, the impact of each drug on treatment outcomes as well as the impact of characteristics of mycobacteriology will be analyzed. The inclusion criteria for the study are as follows: fulfilling the criteria for NTM-PD having one of the following etiologic organisms: Mycobacterium avium complex, M. abscessus subspecies abscessus, M. abscessus subspecies massiliense, or M. kansasii; receiving the first treatment for NTM-PD after enrollment; age >20 years; and consenting to participate in the study. Seven institutions will participate in patient enrollment and about 500 patients are expected to be enrolled. Participants will be recruited from 1 March 2020 until 19 March 2024 and will be observed through 19 March 2029. During the follow-up period, participants' clinical course will be tracked and their clinical data as well as NTM isolates will be collected.CONCLUSION: NTM-KOREA will be the first nationwide observational cohort for NTM-PD in South Korea. It will provide the information to optimize treatment modalities and will contribute to deeper understanding of the treatment outcomes and long-term prognosis of patients with NTM-PD in South Korea.

BACKGROUND: The burden of nontuberculous mycobacterial (NTM) pulmonary disease (PD) is increasing globally. To understand the treatment outcomes and prognosis of NTM-PD, a unified registry is needed. In this project, we aim to construct a multicenter prospective observational cohort with NTM-PD in South Korea (NTM-KOREA). METHODS: The primary objective of this study is to analyze treatment outcomes according to the species. In addition, recurrence rate, adverse events, the impact of each drug on treatment outcomes as well as the impact of characteristics of mycobacteriology will be analyzed. The inclusion criteria for the study are as follows: fulfilling the criteria for NTM-PD having one of the following etiologic organisms: Mycobacterium avium complex, M. abscessus subspecies abscessus, M. abscessus subspecies massiliense, or M. kansasii; receiving the first treatment for NTM-PD after enrollment; age >20 years; and consenting to participate in the study. Seven institutions will participate in patient enrollment and about 500 patients are expected to be enrolled. Participants will be recruited from 1 March 2020 until 19 March 2024 and will be observed through 19 March 2029. During the follow-up period, participants' clinical course will be tracked and their clinical data as well as NTM isolates will be collected. CONCLUSION NTM-KOREA will be the first nationwide observational cohort for NTM-PD in South Korea. It will provide the information to optimize treatment modalities and will contribute to deeper understanding of the treatment outcomes and long-term prognosis of patients with NTM-PD in South Korea.