[Species identification of Mycobacterium tuberculosis with insertion elements].

The Insertion Sequence(IS) element IS6110 and IS1081 of M. tuberculosis complex were used as template to prepare probes for typing strains by means of restriction fragment length polymorphisms (RFLP). Chromosomal DNA of M. tuberculosis H37Ra, H37Rv, M. bovis digested with EcoR I, Pst I, Sal I, BamH I, Pvu II was subjected to Southern Blot analysis With labeled 317bp from IS6110 and 248 bp from IS1081. The results indicated that for M. tuberculosis complex, IS1081 cannot be used to type strains, IS6110 can be used to distinguish strains into broad groups and is an excellent epidemiological tool for studying outbreaks. An investigation of forty-six M. tuberculosis isolates by IS6110 RFLP revealed that M. tuberculosis strains not only are of highly polymorphic, but also are presentin multiple copies ranging from 7 to 18 copies.