Repetitive DNA sequences as probes for Mycobacterium tuberculosis.

Three cloned segments of Mycobacterium tuberculosis DNA which are promising as clinical probes were identified. An MboI digest of DNA from a clinical isolate of M. tuberculosis was cloned into bacteriophage M13. To identify recombinants specific for the M. tuberculosis complex, plaque lifts were hybridized with M. bovis and M. kansasii DNA. Recombinants which selectively hybridized with M. bovis DNA were characterized by probing slot blots and restriction digests of DNA from various mycobacteria. Three recombinants that did not hybridize to a significant extent with DNA from nontuberculous mycobacteria were identified. These three probes are of special interest because they are each repeated multiple (10 to 16) times in the M. tuberculosis chromosome. These probes were also shown to be useful for fingerprinting strains for epidemiological studies.