Application of molecular biology techniques to the diagnosis of nontuberculous mycobacterial infections

A total of 19,723 clinical samples were cultivated for the detection of mycobacteria from January 1995 to March 2001. The 203 strains of nontuberculous mycobacteria isolated were identified with the use of molecular techniques in combination with traditional biochemical tests. The molecular methods applied were PCR-restriction fragment length polymorphism analysis (PRA) alone or in combination with 16S rRNA and 16S-23S spacer sequencing. The patient records of those with specimens positive for mycobacteria were analysed to evaluate the clinical significance of the culture results. Twenty-five of the 124 patients analysed (20%) were regarded as having clinical mycobacteriosis. The main species associated with mycobacteriosis were: Mycobacterium avium (13 cases), M. intracellulare (2 cases), M. kansasii (5 cases), M. chelonae (2 cases), M. malmoense (1 case), M. scrofulaceum (1 case) and M. marinum (1 case). The use of PRA alone or in combination with gene sequencing provided valuable help in discerning mycobacteria at both the intra- and interspecies level, thus contributing to a faster and more efficient diagnosis and epidemiological follow-up.