[Systematics, differentiation, and detection of bacterial infections-- the family Mycobacteriaceae]

Comparative 16S rRNA sequencing allows to infer natural relationships among bacteria, to characterize and identify microorganisms at a molecular level and to develop DNA probes specific at any desired taxonomic level (e.g. family, genus, species). Probes targeted at ribosomal RNA are suitable for in situ hybridization of whole, intact bacterial cells as well as in polymerase-chain-reaction techniques for sensitive detection and identification of bacteria. Comparative 16S rRNA sequencing provided the basis for a systematic phylogenetic analysis of the genus Mycobacterium. Certain growth characteristics, i.e. thermotolerance and growth rate correspond to natural relationships among the mycobacteria. However, the phylogenetic relatedness within the slow-growing species did not reflect the Runyon classification of photochromogenic, scotochromogenic and nonphotochromogenic mycobacteria. The use of oligonucleotides targeted at highly or semi-conserved regions within the 16S rRNA molecule allows a universal procedure for amplification and rapid sequence determination of 16S rDNA-gene fragments from any virtually bacterial organism. This method of amplification of 16S rDNA-gene fragments was used to identify a novel, uncultured pathogen and opens new perspectives for other infectious diseases of unknown cause.