Gene Xpert MTB/RIF assay in bronchoscopy guided bronchial wash specimens in sputum negative pulmonary tuberculosis: Sensitive, rapid and most useful test for drug sensitive and drug resistant tuberculosis

Abstract

Prospective study conducted in department of Pulmonary Medicine, MIMSR Medical College, and Latur India during Jan 2013- Jun 2015, enrolled 250 sputum negative pulmonary Tuberculosis cases on clinical and radiological basis. All study cases undergone bronchoscopy and three aliquots of bronchial wash specimens were collected, first for Zeihl Neelson staining for MTB, second for Gene expert MTB/RIF assay and third for MGIT 960 liquid culture for MTB respectively. Bronchial wash for MTB detected 62/250 (24.8%), in Gene Xpert MTB/RIF assay MTB genome was positive in 228/250 (91.2%) and Rifampicin resistance was positive in 12/250 (4.8%), and MGIT culture was positive in 244/250 (97.6%). We have stared Antituberculosis chemotherapy to all the 250 cases as our National TB control guidelines for drug sensitive and drug resistant TB cases. Clinical and Radiological response was observed in nearly all the drug sensitive TB cases except few MDR (multi drug resistance) cases where response to chemotherapy was delayed up to 14 months of therapy. Gene Xpert is rapid, sensitive and specific not only for acid fast bacilli (AFB) detection but also for rifampicin (RIF) resistance which is a surrogate marker for MDR TB, should be used routinely as it will save time. It is alternative to conventional tests as it is reliable, cost effective and can be performed on all bronchoscopic samples. Gene Expert should be used in all sputum negative pulmonary tuberculosis cases where conventional diagnostic tests are less sensitive and more time consuming.