A review on Diagnostic practices for Mycobacterium Tuberculosis

Tuberculosis (TB) infection is one of the main health problems facing society today. It is still responsible for millions of deaths per year. It especially poses a problem in areas ravaged by the HIV pandemic, which almost seems to work hand in hand with TB. The appearance of drug resistant (MDR-TB) variants of the disease have only worsened the situation. For this reason global initiatives, coordinated by the WHO, have been set up to decrease the spread of TB. These efforts have had effect, yet there are still many problems. Patients require long and intensive treatment and the standard diagnostic methods, although accurate, are often too slow. In order to increase the speed in which TB can be detected and treated, thereby stopping its ability to spread. New methods must be found that are capable of quickly and accurately detecting a TB infection. This review sets out to compare the different diagnostic tools available, to the current gold standard; culturing. We do so by comparing the methodologies on; speed, specificity, sensitivity, costs and practicality. While doing that, the study also takes into account the ability of the assays to detect for drug susceptibility. The analysis of this study shows that there isn’t any one method available that fully meets all the requirements. However it can clearly be stated that with the advances in culturing technology, culturing remains an essential component of the diagnosis of TB. Techniques such as the mantoux test or IFN- assays just don’t provide the accurate diagnosis required. Techniques such as High Performance Liquid Chromatography (HPLC), while fast and accurate, don’t offer the ability to screen for resistance to drugs. At the same time other molecular based techniques, such as the Nucleic Acid Amplification Tests (NAATs) have made their entry into the field, these tests are fast yet not always accurate. Really only one new technique, Xpert MBT/RIF, has the ability to fully complement culturing in the diagnosis. Going on the findings of this study it should be considered to be the first line in TB detection and general resistance screening.