Cepheid GeneXpert Mycobacterium tuberculosis/Rifampicin assay for the rapid detection of Mycobacterium tuberculosis and identification of Rifampicin resistance

Abstract

CONTEXT: Rapid diagnosis and detection of Rifampicin (RIF) resistance are essential for effective disease management of tuberculosis (TB). Cartridge-based nucleic acid amplification test also known as GeneXpert Mycobacterium tuberculosis (MTB)/RIF assay is a novel integrated diagnostic system for the diagnosis of TB and rapid detection of RIF resistance in clinical specimens. AIM: In the present study, we determine the performance of the MTB/RIF assay for the rapid diagnosis of TB and detection of RIF resistance in pulmonary specimens obtained from presumptive multidrug-resistant (MDR) TB cases. SUBJECTS AND METHODS: This is a cross-sectional observational study conducted in culture and drug-susceptibility testing laboratory between January 2014 and December 2014. A total of 1994 sputum samples were obtained from presumptive MDR-TB cases of Dharwad and Belgaum districts of Karnataka. All samples were tested on GeneXpert for MTB/RIF detection. RESULTS: A total of 1994 presumptive pulmonary TB clinical samples were received of which 840 (42.1%) were MTB complex (MTBC) positive and 1154 (57.9%) were negative. The MTB/RIF assay also detected 127 (6.4%) RIF-resistant specimen and 713 (35.6%) RIF-susceptible specimens. CONCLUSIONS: The MTB/RIF test is a simple and rapid method, and staff with adequate training can perform this test with minimal laboratory setup. It helps to avoid the injudicious use of the anti-TB drug and offers high potential for the diagnosis of TB and RIF resistance due to its capacity for direct detection of MTBC, its rapidity and its simplicity.