ABSTRACT
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.