Gas chromatographic detection of Mycobacterium tuberculosis complex in pure cultures from respiratory specimens

It is important to identify mycobacteria to the species level in order to establish their clinical significance and to take the appropriate therapeutical decision. Biochemical tests on primary cultures take time (3-6 weeks) until the report of results; that's why more rapid techniques are needed. We have used gas chromatography with flame-ionisation detection (GC-FID) as an alternative identification method for 53 mycobacterial strains isolated from respiratory specimens. We have extracted fatty acids from whole mycobacterial cells, then derivatized them into methylesters, detectable by GC-FID. All the strains were identified as M. tuberculosis complex (MTC), using the Microbial Identification System (MIS) software. The specificity of the identification by GC-FID of MTC is 100%. In conclusion, pulmonary mycobacteriosis are dominated by MTC; GC-FID is a rapid and accurate method for the identification of MTC.