Isolation of specific DNA fragments of Mycobacterium avium and their possible use in diagnosis.

We cloned and sequenced two DNA fragments (DT1 and DT6) from Mycobacterium avium serotype 2 for use in the identification of members of the M. avium-M. intracellulare complex (MAC). Reference strains of MAC belonging to serovars 1 to 28 were examined by using these DNA fragments as probes. The study revealed that the DT6 probe hybridized with DNAs from M. avium strains (serovars 1 to 6, 8 to 11, and 21), while the DT1 probe hybridized with DNAs from serovars 2, 3, 7, 12 to 20, and 23 to 25. DT1- and DT6-derived oligonucleotides were selected for use as primers in a polymerase chain reaction test. Amplification of the DT1 and DT6 sequences may provide the basis for a rapid and reliable assay for the detection of mycobacteria belonging to MAC.