Evaluation of the GeneXpert MTB/RIF Assay for Rapid Diagnosis of Tuberculosis and Detection of Rifampin Resistance in Pulmonary and Extrapulmonary Specimens

Abstract

Mycobacterium tuberculosis remains one of the most significant causes of death from an infectious agent. The rapid diagnosis of tuberculosis and detection of rifampin (RIF) resistance are essential for early disease management. The GeneXpert MTB/RIF assay is a novel integrated diagnostic device for the diagnosis of tuberculosis and rapid detection of RIF resistance in clinical specimens. We determined the performance of the MTB/RIF assay for rapid diagnosis of tuberculosis and detection of rifampin resistance in smear-positive and smear-negative pulmonary and extrapulmonary specimens obtained from possible tuberculosis patients. Two hundred fifty-three pulmonary and 176 extrapulmonary specimens obtained from 429 patients were included in the study. One hundred ten (89 culture positive and 21 culture negative for M. tuberculosis) of the 429 patients were considered to have tuberculosis. In pulmonary specimens, sensitivities were 100% (27/27) and 68.6% (24/35) for smear-positive and smear-negative specimens, respectively. It had a lower sensitivity with extrapulmonary specimens: 100% for smear-positive specimens (4/4) and 47.7% for smear-negative specimens (21/44). The test accurately detected the absence of tuberculosis in all 319 patients without tuberculosis studied. The MTB/RIF assay also detected 1 RIF-resistant specimen and 88 RIF-susceptible specimens, and the results were confirmed by drug susceptibility testing. We concluded that the MTB/RIF test is a simple method, and routine staff with minimal training can use the system. The test appeared to be as sensitive as culture with smear-positive specimens but less sensitive with smear-negative pulmonary and extrapulmonary specimens that include low numbers of bacilli.

Bronchial wash Gene Xpert MTB/RIF in lower lung field tuberculosis: Sensitive, superior, and rapid in comparison with conventional diagnostic techniques

“…Culture of bronchoscopy sample for MTB was not done because of time factor, cumbersome, and cost effectiveness. Similar yields were documented in studies by Pierrae et al [31] as 80%, Bernard et al [32] as 92.3%, Khalil et al [33] as 91.86%, Lee et al [34] as 81.6%, and Surendra et al [35] as 90%, and few other studies [36][37][38][39] from various authors documented sensitivity between 57% and 75%.…”

Quantification of circulating Mycobacterium tuberculosis antigen peptides allows rapid diagnosis of active disease and treatment monitoring

“…NanoDisk-MS thus dramatically outperformed Mtb culture-based diagnosis of PTB (57.5%; 23 of 40) and EPTB (61.9%; 13 of 21) cases, and exhibited 100% and 84.3% sensitivity for smear-positive and -negative cases, respectively. These sensitivities also exceed those found in a study analyzing Xpert MTB/RIF sensitivities for culture-positive PTB cases (86.2%; 50 of 58) and culture-positive (67.7%; 21 of 31) and -negative (29.4%; 5 of 17) EPTB cases in a HIV-positive population (27).…”

Comparison and evaluation of diagnostic techniques of mycobacterium tuberculosis in Iraq

“…These results agreed with the work reported by Zeka et al,20 who suggested that the X-pert MTB/RIF assay have reported test sensitivities of 57 to 76.9% in cases of smear-negative. In our study, real-time PCR has a second value of sensitivity (69%) for smear negative after the Gene X-pert.…”