Identification of Mycobacterium xenopi by gas chromatography

For the purposes of the following study we cultured 32 strains of Mycobacterium xenopi isolated from clinical specimens and several strains of other slowly growing mycobacteria. The cultures were grown in liquid medium and then analysed--after saponification, methylation, extraction with organic solvent and washing of the organic phase--using a highly sensitive manual gas-liquid chromatographic assay for the determination of secondary alcohol 2-OH-docosanol. The percentage of this compound was compared with that previously measured in strains of Mycobacterium xenopi grown on solid medium. The presence of this specific alcohol was always apparent, even though its quantity was lower than that obtained by growing mycobacteria on solid medium. The absence of interference peaks around the compound was checked by analyzing strains of other slowly growing mycobacteria in the same conditions.