Gas chromatographic characterization of porcine and human strains belonging to the Mycobacterium avium-intracellulare complex.

Trifluoroacetylated whole-cell methanolysates of 23 strains designated as belonging to the Mycobacterium avium-intracellulare complex by biochemical, growth chromogenicity and chicken pathogenicity tests, were analysed by gas chromatography. Twenty of the strains were isolated from pigs and the remainder from human beings. Serological typing showed that 13 of the porcine strains, but none of the human strains, belonged to M. avium. The remaining strains, except one which showed autoagglutination, did not react with antisera to M. avium (serotypes 1-3), thus suggesting that they belonged to M. intracellulare. Five different, highly reproducible chromatographic patterns, the main peaks of which were considered as representing bacterial carbohydrates and fatty acids, could be distinguished by visual examination and by cluster analysis. The chromatographic results could not be correlated with those obtained from serotyping of the strains studied. Mycobacteria recovered from different organs of one and the same pig gave virtually identical chromatograms. The strains isolated from three human beings had a chromatographic pattern which was identical with one of those produced by the porcine strains. The present investigation indicates that the gas chromatographic analytic technique used differentiates bacteria within the M. avium-intracellulare complex, without assigning the organisms to species.