Different molecular methods for the identification of rarely isolated non-tuberculous mycobacteria and description of new hsp65 restriction fragment length polymorphism patterns.

Analysis of heat shock protein 65 (hsp65) gene restriction fragment length polymorphism (RFLP) is done frequently to identify non-tuberculous mycobacteria (NTM) on a genetic basis. Here we report the results of analysing the hsp65 patterns of some rarely isolated NTM for which patterns have not been published before (Mycobacterium bohemicum, Mycobacterium hassiacum, Mycobacterium heckeshornense, Mycobacterium monacense, and Mycobacterium triplex). Furthermore new hsp65-variants for Mycobacterium interjectum (type II), Mycobacterium mucogenicum (type V), Mycobacterium gordonae (type VIII) and Mycobacterium paraffinicum (perhaps synonymous to Mycobacterium scrofulaceum) are described. All species were characterised by hsp65-RFLP, sequencing a 441-bp fragment of the hsp65 gene and sequencing the hypervariable region of the 16S rDNA. Additional data for less frequently isolated mycobacteria are provided and the hitherto described data for the Mycobacterium gordonae complex are summarised. Although the hsp65-RFLP analysis turned out to be a useful method a number of restraints (lack of standardisation, slight variability in fragment length) limits its broader use. Reliable identification of NTM needs, however, more than one molecular method. Identification results obtained by applying different methods yielded conflicting results. Confusion may be caused by older data base entries which are not updated and not longer reflect the actual systematic and taxonomy of the genus Mycobacterium.