[Specific detection of Mycobacterium tuberculosis in clinical material by PCR and Southern blot]

An amplified fragment of 245 base pairs from IS-986 sequence hybridized specifically with DNA of M. tuberculosis complex strains. The fragment was labelled with digoxigenin. After amplification by PCR and southern blot hybridization with the dig-labelled probe, the limit of detection of purified genomic M. tuberculosis DNA amounted to 1 fg. We detected sputum, pleural and synovial fluid with active tuberculosis by PCR and southern blot, and the sensitivities were 81.0%, 64.2% and 57.7%, respectively. From the result of the experiment, it is a very useful method for diagnosis of tuberculosis by combining PCR with Southern blot.