Xpert MTB/RIF and GenoType MTBDRplus assays for the rapid diagnosis of bone and joint tuberculosis.
Bone and joint tuberculosis (BJTB) constitutes about 10-20% of the extrapulmonary tuberculosis (EPTB) cases in China. The GenoType MTBDRplus assay (MTBDR) has been endorsed by the World Health Organization (WHO) for the diagnosis of pulmonary TB (PTB), while the Xpert MTB/RIF assay (Xpert) has also been endorsed by the WHO for the diagnosis of both PTB and EPTB. The diagnostic utility of these two techniques for BJTB was investigated prospectively.
Sixty pus specimens were obtained from orthopedic patients. Smear, culture, Xpert, and MTBDR assays were performed for each specimen, and MGIT 960-based drug susceptibility testing (DST) was conducted for all of the isolates recovered. The diagnostic efficiency of Xpert and MTBDR was evaluated on the basis of bacteriological examination and the composite reference standard (CRS).
Fifty of the 60 patients were considered to have BJTB according to the CRS. The sensitivities of smear, culture, Xpert, and MTBDR were 26% (13/50), 48% (24/50), 82% (41/50), and 72% (36/50) respectively, while the specificities of all of the tests were 100% (10/10). Xpert was 100% concordant with MGIT 960-based DST for the detection of rifampicin resistance. MTBDR had a sensitivity of 83.3% and a specificity of 100% for the detection of rifampicin resistance and a sensitivity of 85.7% and specificity of 100% for the detection of isoniazid resistance.
With their high sensitivities, short turnaround times, and ability to diagnose TB and detect drug resistance simultaneously, both Xpert and MTBDR are feasible as diagnostic tools for BJTB in clinical practice.
Gu Y
，Wang G
，Dong W
，Li Y
，Ma Y
，Shang Y
，Qin S
，Huang H
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Diagnostic value of Xpert MTB/RIF Ultra for osteoarticular tuberculosis.
The diagnosis of osteoarticular tuberculosis (TB) remains challenging and results in under- or over-diagnosis. The aim of the present study was to evaluate performance of the novel next-generation Xpert MTB/RIF Ultra (Xpert Ultra) in comparison to culture and Xpert MTB/RIF (Xpert) for osteoarticular TB diagnosis in high burden settings.
Osteoarticular TB suspected cases were enrolled consecutively during June 2017 to June 2018 at Beijing Chest Hospital and their pus specimens were subjected to smear, culture, Xpert and Xpert Ultra. Drug susceptibility testing (DST) was conducted for all of the recovered isolates. The performances of Xpert Ultra and Xpert were evaluated using composite reference standard (CRS) as gold standard, which included clinical, laboratory, histopathological, radiological and ≥6 months' follow-up data.
In total, 186 patients were recruited, and 132 of them were diagnosed with osteoarticular TB according to CRS. The direct head-to-head performance comparison for M. tuberculosis detection showed that Xpert Ultra (90.91%, 120/132) produced a higher sensitivity than Xpert (78.79%, 104/132, P = 0.006) and culture (39.39%, 52/132, P < 0.001). When Xpert Ultra outcomes were integrated, the percentage of confirmed osteoarticular TB case increased from 84.09% (111/132) to 93.94% (124/132). The specificities of Xpert and Xpert Ultra were 100% (34/34) and 97.06% (33/34), respectively. Both Xpert Ultra and Xpert accurately identified all of the 9 rifampicin (RIF)-resistant and 38 RIF-sensitive cases defined by phenotypic DST. Therefore, Xpert Ultra was 100% concordant with phenotypic DST for the detection of RIF resistance.
Xpert Ultra detected significantly more osteoarticular TB cases than Xpert or culture, making it a useful tool for rapid diagnosis of osteoarticular TB.
Sun Q
，Wang S
，Dong W
，Jiang G
，Huo F
，Ma Y
，Huang H
，Wang G
... -
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Diagnostic accuracy of the Xpert MTB/RIF assay for bone and joint tuberculosis using tissue specimens.
To evaluate the diagnostic accuracy of the Xpert MTB/RIF assay for bone and joint tuberculosis (BJTB) using tissue specimens, and to compare the diagnostic accuracy of different types of tissue specimens.
This study involved 242 patients admitted with suspected BJTB between May 2018 and March 2020. The Xpert MTB/RIF assay was performed on surgically excised tissue. Diagnostic accuracy of the Xpert MTB/RIF assay was evaluated by culture, histopathology and a composite reference standard (CRS).
One hundred and seventy-five patients were excluded (91 based on the exclusion criteria, and 84 as pus specimens were used instead of tissue specimens). Of the 67 patients enrolled, 14 were confirmed as BJTB, 20 as probable BJTB, 11 as possible BJTB, and 22 as non-BJTB. Using culture as the reference standard, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the curve (AUC) of the Xpert MTB/RIF assay were 92.9% (88.2-97.6%), 62.3% (56.1-68.5%), 39.4% (33.2-45.6%), 97.1% (92.3-100.0%), 2.464 (1.077-3.851), 0.114 (0.025-0.203) and 0.776 (0.654-0.897), respectively. When histopathology was used as the reference standard, the Xpert MTB/RIF assay had sensitivity, specificity, PPV, NPV, PLR, NLR and AUC of 79.3% (73.5-85.1%), 73.7% (67.8-79.6%), 69.7% (63.8-75.6%), 82.4% (76.5-88.3%), 3.015 (1.184-4.846), 0.281 (0.141-0.421) and 0.765 (0.646-0.884), respectively. Sensitivity, specificity, PPV, NPV, PLR, NLR and AUC obtained when using CRS as the reference were 73.3% (67.9-78.7%), 100.0% (100.0-100.0%), 100.0% (100.0-100.0%), 64.7% (58.5-70.9%), +∞, 0.267 (0.129-0.405) and 0.867 (0.781-0.952), respectively. Tissue samples were classified, and the positive rate of the Xpert MTB/RIF assay for BJTB using granulation tissue specimens was found to be significantly higher than that for caseous necrotic tissue, sequestrum and other necrotic connective tissues (P < 0.05).
The Xpert MTB/RIF assay showed high sensitivity and specificity for the diagnosis of BJTB from tissue specimens.
Zhou Z
，Zheng Y
，Wang L
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ResearchGate
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