Evaluation of Role of Xpert MTB/RIF in Diagnosis of Extra Pulmonary Tuberculosis in Patients attending Tertiary Care Hospital

BACKGROUND: Globally extra pulmonary tuberculosis (EPTB) accounts for 25% of all tuberculosis cases. The Gene Xpert MTB/RIF assay is a newly developed, automated diagnostic molecular test recommended by WHO for diagnosing EPTB. In the current situation determination of MDR status is also important. Thus Xpert MTB/RIF assay plays a major role in diagnosing extrapulmonary tuberculosis and MDR status. AIM OF THE STUDY: To evaluate Xpert MTB/RIF assay in diagnosing Mycobacterium tuberculosis in extra pulmonary samples. MATERIALS AND METHODS: Around 500 extra pulmonary samples from patients suspected of extrapulmonary tuberculosis were tested. We evaluated the sensitivity and specificity of Xpert MTB/RIF with gold standard liquid culture and composite gold standard. Individually each sample type were analysed against liquid culture. RESULTS: In total 500 extrapulmonary samples were analysed against culture and composite gold standard. Compared to gold standard liquid culture, the sensitivity and specificity of Gene Xpert MTB/RIF assay was 94.7% and 99.5% respectively. While using Composite Gold Standard, Xpert MTB/RIF assay showed a pooled sensitivity of 63.5% and specificity of 99.5%. Multidrug resistance tuberculosis was reported in 5.35% of extrapulmonary samples. CONCLUSION: We conclude that Xpert MTB/RIF assay can be used for diagnosing extra pulmonary tuberculosis with a good sensitivity and specificity. It also allows rapid identification of MDR TB.