Restriction endonuclease analysis of members of the Mycobacterium avium-M. intracellulare-M. scrofulaceum serocomplex.

Organisms belonging to the Mycobacterium avium-M. intracellulare-M. scrofulaceum (MAIS) serocomplex were subjected to restriction endonuclease analysis (REA) with the enzymes BstEII, PvuII, and BclI. Substantial genetic heterogeneity was observed between members of an authenticated collection of the 31 serotypes. Serotypes 2 and 3 were indistinguishable, however, as were serotypes 5 and 10. No direct correlation could be made between restriction pattern and species identification. REA of serotype 2 and serotype 8 isolates from various geographic locations and animal origins showed that, within limits, the restriction pattern could be used as an index of serotype. Some isolates that were unable to be classified serologically exhibited restriction patterns identical to those of strains that were able to be classified by seroagglutination. The difficulty of interpreting much of the epidemiological data concerning MAIS organisms may be partially explained by the extent of heterogeneity observed by REA. These findings support the contention that the MAIS complex has a substantially greater degree of heterogeneity than has been revealed by traditional methods.