Yield of Xpert MTB/RIF Assay in Extra Pulmonary Specimens of Patients at Tertiary Care Hospital

Abstract

Abstract:Background: Tuberculosis (TB) is the world’s leading cause of infectious disease that leads to death and now ranked above AIDS. It is caused by bacteria, Mycobacterium tuberculosis. According to WHO in 2017, 10.4 million people became victim of this infection and 1.8 million of them were died due to this deadly infection. Although TB most commonly infect lungs (pulmonary TB), yet it can spread to sites other than lungs during latent phase of the disease and called as extra-pulmonary Tuberculosis (EPTB). Newer diagnostic techniques like nucleic acid amplification are exceptional for their sensitivity and specificity for detection of MTB in EPTB. One of these latest techniques is GeneXpert MTB/RIF assay.Method:  The specimens of the patients, who are clinically suspected as having TB other than lungs e.g Pleural effusions, lymph node biopsies, pericardial fluids, ascetic fluids, Cerebrospinal Fluids, urine, joints fluid, bone marrow aspirates, gastric aspirates, stool and skin scrapings were included in the present study. Specimens of pulmonary tuberculosis like Sputum, Broncho-alveolar lavage and blood were excluded from the study. All samples were processed according to standard operating procedures and Gene Xpert was done.Results: Total 339 samples of extra-pulmonary TB were collected and processed. Out of these 339 samples, MTB detected in 35 EP samples. Most of these samples were collected from pulmonology and pediatrics departments. Most common sample that was received was gastric aspirates. Conclusion: Yield of MTB RIF assay was low in our study, though GeneXpert MTB/RIF assay is a very sensitive nucleic acid amplification tests but clinically this test is over-prescribed.