Direct detection of Mycobacterium tuberculosis in sputum: A validation study using solid phase extraction-gas chromatography–mass spectrometry

•Detection of Mycobacterium tuberculosis directly in sputum using SPE-GC–MS.•Five lipid biomarkers for identification of Mycobacterium tuberculosis.•A new step towards a portable GC system for tuberculosis diagnosis. Tuberculosis (TB) remains a worldwide health problem, especially in developing countries. Correct identification of Mycobacterium tuberculosis (MTB) infection is extremely important for providing appropriate treatment and care to patients. Here we describe a solid phase extraction-gas chromatography-mass spectrometry method (SPE-THM-GC–MS) for the detection of five biomarkers for M. tuberculosis. The method for classification is developed and validated through the analysis of 112 sputum samples from patients suspected of having TB. Twenty of twenty-five MTB culture-positive sputum samples were correctly classified as positive by our improved SPE-THM-GC–MS method. Eighty-five of eighty-seven MTB culture-negative samples were also negative by SPE-THM-GC–MS. The overall sensitivity of the new SPE-THM-GC–MS method is 80% (20/25) and the specificity is 98% (85/87) compared with culture. The method proved to be reliable and, although complex in principle, easy to operate due to the high degree of automation.