The WHO declared tuberculosis (TB) a global emergency. An estimated 8-9 million new cases occur each year with 2-3
million deaths. Currently, TB is diagnosed mostly by chest-X ray and staining of the mycobacteria in sputum with a
detection limit of 1x10<sup>4</sup> bacteria /ml. There is an urgent need for better diagnostic tools for TB especially for developing
countries. We have validated the electronic nose from TD Technology for the detection of <i>Mycobacterium tuberculosis</i> by headspace analysis of 284 sputum samples from TB patients. We used linear discriminant function analysis resulting in a sensitivity of 75% a specificity of 67% and an accuracy of 69%. Further research is still required to improve the results by choosing more selective sensors and sampling techniques.
We used a fast gas chromatography- mass spectrometry method (GC-MS). The automated procedure is based on the injection of sputum samples which are methylated inside the GC injector using thermally assisted hydrolysis and methylation (THM-GC-MS). Hexacosanoic acid in combination with tuberculostearic acid was found to be specific for the presence of <i>M. tuberculosis</i>. The detection limit was similar to microscopy. We found no false positives, all microscopy and culture positive samples were also found positive with the THM-GC-MS method.
The detection of ribosomal RNA from the infecting organism offers great potential since rRNA molecules outnumber chromosomal DNA by a factor 1000. It thus may possible to detect the organism without amplification of the nucleic acids (NA). We used a capture and a tagged detector probe for the direct detection of <i>M. tuberculosis </i>in sputum. So far the detection limit is 1x10<sup>6</sup> bacteria / ml. Currently we are testing a Lab-On-A-Chip Interferometer detection system.