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GeneXpert MTB/RIF Assay (PCR Mycobacterium Tuberculosis): A Revolution in Management of Tuberculosis

Muhammad Siyar, Imtiaz Uddin, Usman Ali


Background: Workup of pulmonary tuberculosis depends upon sputum microscopy. Sputum microscopy is less sensitive, human resource dependent and time consuming. Sometimes, it lead us to a delay in the diagnosis and may result in the spread of the disease. This seriously disturbs TB control program. There is a need for a more sensitive method. Similarly, early detection of rifampicin resistance is also of utmost importance to prevent MDR strains from spread. These both problems can be solved through DNA testing of mycobacterium. Aims and objectives: To study the diagnostic value of GeneXpert MTB/RIF Assay (GX) systems considering sensitivity, specificity and rifampicin resistance. Place of Study: Mardan Medical Complex (MMC), KPK, Pak, 2017. Study design: Cross sectional. Methods: Known patients of sputum positive and negative pulmonary tuberculosis were analyzed by GX system for detection and rifampicin resistance in KPK. Study was conducted in MMC Mardan for year 2017. Pattern of resistance from 2012 to 2017 was also analyzed. Sputum negative and positive patients were analyzed through GX Assay. Results: GX showed sensitivity >99%, specficity100%, positive predictive (PPV) 100% and negative predictive (NPV) value of >99% considering sputum smear as standard. Rifampicin resistance is detected from 5.5 to 1.8% during last 6 years in district Mardan. It was 5.5, 3.6, 5.2, 5.5, 3.6 and 1.8% in 2012, 13, 14, 15, 16 and 2017 respectively. Conclusion: GeneXpert test is much more useful for early detection of rifampicin resistance. It has been introduced at specific convenient, decision making stages of treatment in TB control program in many high load counties including Pakistan, India, Bangladesh, Russia, Nepal, China, Korea, Ethopia, Congo and Brazil to detect MDR much earlier. It is not useful to replace sputum microscopy in TB control program due to comparable efficacy but high cost, though it is useful for selected difficult smear negative, pleural, peritoneal, CSF and lymph node tuberculosis.


Keywords: GeneXpert MTB/RIF assay, MDR, MMC

Cite this Article

Muhammad Siyar, Imtiaz Uddin, Usman Ali. GeneXpert MTB/RIF Assay (PCR Mycobacterium Tuberculosis): A Revolution in Management of Tuberculosis. Research & Reviews: A Journal of Immunology. 2018; 8(2): 8–12p.

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