Airwaves
WHY DO MYCOBACTERIA SHOW DIFFERENT PATHOGENICITY?
The various Mycobacterium species causing pulmonary disease show different virulence, with M avium complex causing mainly airway inflammation while M tuberculosis primarily affects the alveoli. In this issue of Thorax Middleton and colleagues describe several original observations on the interaction of three mycobacterial species with respiratory mucosa. Although the initial interaction of the individual mycobacteria is similar, differences were observed after 14 days in an organ culture model. M avium complex multiplies on the mucosal surface and the number of bacteria recovered increased, M tuberculosis decreased on the surface and multiplied in the tissue showing invasion, while M smegmatis—which is considered non-pathogenic—was eradicated. This study raises a number of issues for further research, particularly the mechanisms of mucosal invasion by mycobacteria.
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TEM section showing M tuberculosis penetrating unciliated respiratory mucosa. Large arrow = M …
