[Commemorative lecture of receiving Imamura Memorial Prize. I. Studies on bacteriological diagnostic methods for mycobacteria].

Two systems, radiometric BACTEC and biphasic MB-Check, 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. The polymerase chain reaction (PCR) using oligonucleotides based on the repetitive sequence (IS986) of M. tuberculosis as a primer and the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (MTD), which combines an M. tuberculosis rRNA amplification method with the hybridization protection assay format, were evaluated for detection of M. tuberculosis in clinical samples. Although the sensitivities of the PCR and MTD appeared to be similar to that of culture with the MB-Check system, the two methods based on nucleic acid amplification should be very useful for rapid detection of M. tuberculosis infections without the long time required for culture of M. tuberculosis. Epidemiological studies with techniques which allow differentiation of strains within M. tuberculosis groups are important for limiting the dissemination of the disease. We analyzed six groups of small outbreaks of M. tuberculosis infections by restriction fragment length polymorphism (RFLP) analysis. Five showed identical fingerprints within each group, but one which as also suspected to have a common source of infection showed different banding patterns, emphasizing that RFLP analysis using IS986 as a probe is useful in epidemiological studies of tuberculosis.(ABSTRACT TRUNCATED AT 250 WORDS)