SO-CALLED PROBLEM OF UNCLASSIFIED MYCOBACTERIA - A REVIEW

Abstract

The studies which have been reviewed seem to prove that mycobacteria constitute a single group of organisms but with gradations of progressive change. Their final and most clear-cut stage, involving loss of many of their biologic properties but which happens to be toxic for the susceptible animals, is represented by the pathogenic strains. Such a change is reversible and therefore, a saprophytic strain may, under certain conditions, turn into a virulent one, and vice versa. We have brought this about in vitro, so there is little reason to doubt that it also may take place in vivo. This concept of the phylogenetic unity of all mycobacteria has been defended by a great many investigators since the beginning of the century and has been fully demonstrated by recent research. Therefore, it is not surprising that the so-called "atypical" or "unclassified" mycobacteria are found to originate from pathogenic organisms, whether spontaneously or under the influence of antimicrobial drugs. The contrary opinion is based on theoretic considerations which are quite reasonable but which, for lack of convincing proof, cannot be accepted at the moment.