[Utility of gas chromatography for the identification of mycobacterial species]

The human immunodeficiency virus (HIV) epidemic has altered the epidemiological profile of tuberculosis in both industrialized and developing countries. Serious diseases caused by mycobacteria other than Mycobacterium tuberculosis, mostly belonging to the M. avium-intracellulare complex (MAC), have become very common in association with severe immunosuppression. The increase in mycobacterial disease complexity has stimulated the development of more rapid and efficient methods for diagnosis. In the present study, we investigated and assessed the suitability of a gas-liquid chromatography technique for diagnosis of clinically important mycobacteria in Argentina. An identification scheme was developed from the results obtained in a previous study where we characterized the cellular fatty acids and the mycolic acid cleavage products from most frequent species in Argentina. Of 183 isolates tested, 69% were correctly identified to species level and 5% were incorrectly classified. If we only take into account the isolates that could be identified, 93% were correctly identified. Although all of the isolates of M. tuberculosis were correctly identified, four isolates of MAC incorrectly matched by M. tuberculosis. Gas chromatography provides a rapid technique of highly predictive value for mycobacteria identification; it could be used in reference laboratories as a rapid presumptive identification until the biochemical tests are completed.