Rapid identification of mycobacteria using gas liquid chromatography

Methyl esters of fatty acids derived from 110 strains of previously identified mycobacteria representing 17 species and a group of unidentified rapid growers, were examined by gas-liquid-chromatography (GLC). Ten species had specific GLC profiles, which enabled accurate identification; but in 2 groups of species strains shared common profiles. M. bovis, and M. xenopi usually had specific profiles but one strain of each could not be distinguished from M. tuberculosis. The group comprising M. terrae, M. fortuitum, M. chelonei, M. flavescens and rapid growers were generally not well separated by GLC; however, 6 of 12 M. terrae strains, 2 of 3 M. flavescens, and all 5 M. fortuitum strains had specific profiles. Other strains of this group had only common peaks and by GLC were indistinguishable from each other. Using a table of specific and characteristic peaks, 34 of 54 (63%) recent isolates were correctly identified, and 18 (33%) were correctly allocated to groups sharing similar GLC profiles: only 2 isolates were wrongly identified. At present, GLC analysis provides easy and rapid identification of a majority of mycobacteria but cannot replace fully biochemical tests in the identification of medical mycobacteria.