[Advances in diagnostic methods for mycobacteria].

Abstract

Two systems, biphasic MB-Check and radiometric BACTEC, based on liquid media proved to be significantly better than the egg-based solid media for the isolation of mycobacteria from clinical specimens. The difference in the rates of isolation of mycobacteria between two groups of media was more remarkable with smear-negative specimens. The time to the detection of the Mycobacterium tuberculosis complex with MB-Check was shorter than that with the 3% Ogawa egg method but longer than that with BACTEC. A total of 135 sputum specimens were examined by the polymerase chain reaction (PCR) using oligonucleotides based on the repetitive sequence (IS986) of M. tuberculosis as a primer. The PCR gave an overall positivity rate of 84.2%, as compared with 71.9% by smear and 96.9% by culture in the liquid medium, MB-Check. Although the sensitivity of the PCR appeared to be similar to that of culture with the MB-Check system, the PCR should be very useful for rapid detection of M. tuberculosis infections. DNA probe technology facilitates a rapid and specific identification of microorganisms. The diagnostic specificity and sensitivity of the nonradioactive Accuprobe M. tuberculosis complex and Accuprobe M. avium complex culture confirmation tests were nearly 100%. The results of the colorimetric microdilution plate hybridization test (DDH-Mycobacteria) for identification of mycobacteria were consistent with those of biochemical identification. About 90% of clinical isolates could be identified by the DDH kit. Both of these methods may contribute to the rapid diagnosis of mycobacterial infections. Epidemiological studies with techniques which allow differentiation of strains within M. tuberculosis groups are important for limiting the dissemination of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)