Comparison of Amplicor and GeneXpert MTB/RIF Tests for Diagnosis of Tuberculous Meningitis

There are no data about the comparative accuracy of commercially available nucleic acid amplification tests (GeneXpert MTB/RIF and Roche Amplicor) for the diagnosis of tuberculous meningitis (TBM). A total of 148 patients with suspected TBM were evaluated, and cultures served as the reference standard. The sensitivities and specificities (95% confidence interval [CI]) for the Amplicor and Xpert MTB/RIF tests were similar: 46 (31–60) versus 50 (33–67) and 99 (93–100) and 94 (84–99), respectively.     

Accuracy of Lipoarabinomannan and Xpert MTB/RIF Testing in Cerebrospinal Fluid To Diagnose Tuberculous Meningitis in an Autopsy Cohort of HIV-Infected Adults

Point-of-care tests for tuberculous meningitis (TBM) are needed. We studied the diagnostic accuracy of the lipoarabinomannan (LAM) lateral flow assay (LFA), LAM enzyme-linked immunosorbent assay (ELISA), and Xpert MTB/RIF in cerebrospinal fluid (CSF) in an autopsy cohort of Ugandan HIV-infected adults. We obtained written informed consent postmortem from the next of kin. A complete autopsy was done and CSF obtained. We performed LAM LFA (on unprepared and supernatant CSF after heating and spinning), LAM ELISA, and Xpert MTB/RIF on the CSF samples. Accuracy parameters were calculated for histopathological TBM and also for the composite standard, including Xpert MTB/RIF-positive cases. We tested CSF of 91 patients. LAM LFA had a sensitivity of 75% for definite histopathological TBM, ELISA a sensitivity of 43%, and Xpert MTB/RIF a sensitivity of 100% and specificities of 87%, 91%, and 87%, respectively. LAM LFA had a sensitivity of 50% for definite and probable histopathological TBM, ELISA a sensitivity of 38%, and Xpert MTB/RIF a sensitivity of 86% and specificities of 70%, 91%, and 87%, respectively. LAM LFA had a sensitivity of 68% for the composite standard and ELISA a sensitivity of 48% and specificities of 78% and 98%, respectively. The rapid diagnostic tests detected TBM in 22% to 78% of patients not on anti-TB treatment. Point-of-care tests have high accuracy in diagnosis of TBM in deceased HIV-infected adults. LAM LFA in CSF is a useful additional diagnostic tool.     

Diagnostic Accuracy of Xpert MTB/RIF Assay in Extrapulmonary Tuberculosis

Introduction: The WHO endorsed Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, has been evaluated for pulmonary TB in a number of studies but very few have investigated it for extrapulmonary specimens. The present study evaluates the performance of Xpert MTB/RIF assay in the diagnosis of extrapulmonary TB (EPTB). Aim and Objectives: The aim of the study is to determine sensitivity and specificity of Xpert MTB/RIF assay for diagnosis of EPTB and RIF resistance in comparison to culture on Lowenstein–Jensen (LJ) medium and proportion method (PM), respectively. Materials and Methods: A total of 738 specimens from clinically suspected cases of EPTB were subjected to Ziehl–Neelsen staining, Xpert MTB/RIF assay and culture on LJ medium. PM was done on MTB isolates. Results: The sensitivity, specificity of Xpert MTB/RIF assay for diagnosis of EPTB were 84.91% (95% confidence interval [CI] 72.41%–93.25%) and 86.72% (95% CI 83.94%–89.17%) and for RIF resistance detection were 60.00% (95% CI 32.29%–83.66%) and 94.74% (95% CI 73.97%–99.87%), respectively. Among culture-positive cases, the sensitivity of Xpert MTB/RIF assay was 94.12% in smear positive and 80.56% in smear-negative cases. Xpert MTB/RIF showed maximum sensitivity of MTB detection from lymph node specimens (100% [95% CI 54.07%–100.00%]) and other body fluids (100% [95% CI 15.81%–100.00%]). Conclusion: The present study establishes Xpert MTB/RIF assay as a promising tool in the rapid diagnosis of EPTB and detection of RIF resistance.     

Xpert MTB/RIF assay for the diagnosis of extrapulmonary tuberculosis: a diagnostic evaluation study

ObjectivesThe diagnosis of extrapulmonary tuberculosis (EPTB) is often made on clinical suspicion alone, resulting in both under- and overdiagnosis and relatively poor outcomes. In this study, we evaluated the clinical utility of the Xpert MTB/RIF on routinely collected extrapulmonary specimens in Ethiopia.MethodsThis study was carried out at Jimma University Specialized Hospital, Southwest Ethiopia. Extrapulmonary specimens were collected from 572 patients clinically suspected of suffering from EPTB. All specimens were tested for TB by smear microscopy, culture, and Xpert MTB/RIF. The diagnostic accuracy of Xpert MTB/RIF was calculated and compared to a composite reference standard (CRS), comprising clinical and laboratory results.ResultsIn total, 572 extrapulmonary specimens (279 lymph node, 159 pleural, 80 peritoneal, 45 cerebrospinal, and nine pericardial fluids) were tested. The pooled sensitivity and specificity of Xpert MTB/RIF were calculated to be 75% (95% CI 70–80) and 98% (95% CI 97–100) respectively when compared to the CRS. The highest sensitivity was documented for lymph node specimens (90%; 95% CI 86–94), moderate sensitivity for cerebrospinal fluid (53%; 95% CI 28–79), while the sensitivity was lowest for pleural (30%; 95% CI 17–44) and peritoneal (32%; 95% CI 12–51) fluids. Xpert MTB/RIF in addition detected rifampicin resistance in 13 patients, in perfect agreement with results from the line probe assay.ConclusionsXpert MTB/RIF may be used as initial diagnostic tool for testing of lymph node specimens from patients suspected of having TB lymphadenitis. The added value of Xpert MTB/RIF to diagnose pleural or peritoneal TB is limited by its poor sensitivity.     

Diagnostic Accuracy of Xpert MTB/RIF for Extrapulmonary Tuberculosis Specimens: Establishing a Laboratory Testing Algorithm for South Africa

South Africa implemented Xpert MTB/RIF as the initial diagnostic test for pulmonary tuberculosis (TB). Xpert MTB/RIF''s accuracy for diagnosing extrapulmonary tuberculosis (EPTB) was investigated. EPTB specimens (n = 7,916) from hospitalized patients received over a 6-month period at a high-throughput TB referral laboratory in Johannesburg were investigated. Large-volume specimens were centrifuged, tissue biopsy specimens homogenized, and all specimens checked for growth of contaminating bacteria on blood agar. Contaminated samples received NALC-NaOH (N-acetyl-l-cysteine–sodium hydroxide) decontamination prior to liquid culture. Residual specimens (volumes > 1 ml) after inoculation of culture (n = 1,175) were tested using the Xpert MTB/RIF sputum protocol. Using culture as the reference, Xpert MTB/RIF''s overall sensitivity was 59% (95% confidence interval [95% CI], 53% to 65%) and specificity was 92% (CI, 90% to 94%), with the highest sensitivities of 91% (95% CI, 78% to 97%) for pus, 80% (95% CI, 56% to 94%) for lymph node aspirates, and 51% (95% CI, 44% to 58%) for fluids (ascitic, 59%; pleural, 47%). A difference in sensitivities was noticed between specimens classified as having a thick (87% [95% CI, 76% to 94%]) versus clear (watery) (48% [95% CI, 36% to 61%]) appearance. This was unchanged with traces of blood (52% [95% CI, 44% to 60%]) or precentrifugation (57% [95% CI, 28% to 82%]) among clear specimens. Xpert MTB/RIF generated an additional 124 specimen results that were contaminated by Mycobacterial Growth Indicator Tubes (MGIT; 10.5%) and diagnosed rifampin (RIF) resistance earlier (9.6% [25/260]). Xpert MTB/RIF''s performance on EPTB specimens provides very promising results and should be considered for incorporation into national TB guidelines. Xpert MTB/RIF is less affected by contaminating bacteria and reduces laboratory labor and diagnostic delay compared to traditional methods.     

Xpert结核分枝杆菌/利福平试验对结核病及耐多药结核病诊断价值的Meta分析

目的 评估Xpert结核分枝杆菌/利福平（MTB/RIF）试验对结核病的诊断价值.方法 检索PubMed、Medline、中国知网、万方数据库等,收集Xpert MTB/RIF试验对结核病诊断价值的文献,检索起止时间均为建库至2012年6月.2名研究者独立进行资料提取和文献质量评估.采用Meta-Disc 1.4软件进行Meta分析.结果 共纳入26篇文献,其中2篇文献涉及儿童病例,包含了13 270例来自临床患者的检测标本.Meta分析结果显示,Xpert MTB/RIF试验诊断结核病的汇总敏感度为87%（95%CI：86%～88%）、特异度为97%（95%CI：97%～97%）.按照结核病的类型和患者年龄进行亚组分析,Xpert MTB/RIF试验诊断肺结核的敏感度高于肺外结核病,90%（95%CI：89%～91%） vs 76%（95%CI：72%～79%）;诊断涂阴菌阳性和涂阳菌阳性结核病的敏感度分别为74%（95%CI：71%～76%）和99%（95%CI：98%～99%）;对儿童肺结核的诊断敏感度比成人肺结核低,74%（95%CI：65%～83%） vs 90%（95%CI：89%～92%）.Xpert MTB/RIF试验诊断耐多药结核病的敏感度为96%（95%CI：94%～97%）,特异度为98%（95%CI：98%～99%）.结论 Xpert MTB/RIF试验诊断结核病的价值较高,尤其是成人结核病及耐多药结核病.Xpert MTB/RIF试验在儿童结核病中的诊断价值由于纳入文献较少,尚待进一步研究.     

Xpert MTB/RIF assay for diagnosis of pleural tuberculosis

We prospectively investigated the diagnostic utility of the Xpert MTB/RIF (Mycobacterium tuberculosis/rifampin [RIF] resistance) assay in 20 cases with confirmed tuberculous pleural effusion. The sensitivity and specificity of the Xpert assay in pleural fluid were 25% and 100%, respectively. All cases positive by the Xpert assay were also positive by pleural fluid culture.     

Xpert MTB/RIF技术对结核分枝杆菌的诊断价值

目的 对Xpert MTB/RIF技术检测结核分枝杆菌（MTB）的结果进行分析并评估其价值。方法 采集2017年10月~2018年10月本院就诊疑为结核分枝杆菌感染的患者共580例,利用Xpert MTB/RIF技术对其痰液（或体液）标本进行DNA检测,同时将标本进行固体培养及涂片抗酸染色并对检测结果进行比较。结果 Xpert MTB/RIF技术检测MTB的阳性率为18.97%（110/580）,和固体培养法的阳性率18.62%（108/580）相比差异无统计学意义（P＞0.05）;和抗酸染色法的阳性率15.00%（87/580）相比则更为敏感,差异有统计学意义（P＜0.05）。 结论 Xpert MTB/RIF检测技术和固体培养法不相上下,且由于抗酸染色法,可以用于MTB的快速筛选。     

Diagnostic Performance of Xpert MTB/RIF in Tuberculous Pleural Effusion: Systematic Review and Meta-analysis

A systematic review investigating the role of Xpert MTB/RIF in the diagnosis of tuberculous pleural effusion (TPE) was conducted. The pooled sensitivities and specificities of Xpert MTB/RIF were 51.4% and 98.6%, respectively, with culture used as a reference standard and 22.7% and 99.8%, respectively, with a composite reference standard (CRS) used as the benchmark. Xpert MTB/RIF has low sensitivity but excellent specificity in the diagnosis of TPE.     

Comparison of Xpert MTB/RIF with Line Probe Assay for Detection of Rifampin-Monoresistant Mycobacterium tuberculosis

The MTBDRplus line probe assay (LPA) and Xpert MTB/RIF have been endorsed by the World Health Organization for the rapid diagnosis of drug-resistant tuberculosis. However, there is no clarity regarding the superiority of one over the other. In a double-blinded prospective study, we evaluated the efficacy of the Xpert MTB/RIF on samples that were first tested by LPA under the revised national tuberculosis control program of India. A total of 405 sputum samples from suspected drug-resistant tuberculosis patients were included. Of these, 285 smear-positive samples were subjected to LPA. Seventy-two (25.8%) samples showed multidrug resistance, 62 (22.2%) showed rifampin monoresistance, 29 (10.3%) showed isoniazid monoresistance, and 116 (41.5%) were pan-susceptible. Six (2.1%) of the samples gave invalid results. Of the 62 rifampin-monoresistant samples by LPA, 38 (61.4%) showed rifampin resistance, while 21 (33.8%) were found susceptible to rifampin by Xpert MTB/RIF using cartridge version G4. Three (4.8%) samples gave an error. Of the 116 pan-susceptible samples, only 83 were available for Xpert MTB/RIF testing; 4 (5.1%) were rifampin resistant, 74 (94.8%) were susceptible, and 5 (6.0%) showed an error. The 25 discrepant samples were further subjected to MGIT960 drug susceptibility testing. The MGIT960 results showed 100% agreement with LPA results but only 64.4% agreement with Xpert MTB/RIF results. Sequencing analysis of discrepant samples showed 91.3% concordance with LPA but only 8.7% concordance with the Xpert MTB/RIF assay. These findings indicate that by using Xpert MTB/RIF testing we might be underestimating the burden of drug-resistant tuberculosis and indicate that country-specific probes need to be designed to increase the sensitivity of the Xpert MTB/RIF.     

Performance of Cepheid® Xpert MTB/RIF® and TB-Biochip® MDR in two regions of Russia with a high prevalence of drug-resistant tuberculosis

The purpose of this study was to assess the performance of Cepheid® Xpert MTB/RIF® (“Xpert”) and TB-Biochip® MDR (“TB-Biochip”). Sputum specimens from adults with presumptive tuberculosis (TB) were homogenized and split for: (1) direct Xpert and microscopy, and (2) concentration for Xpert, microscopy, culture [Lowenstein–Jensen (LJ) solid media and Mycobacteria Growth Indicator Tube® (MGIT)], indirect drug susceptibility testing (DST) using the absolute concentration method and MGIT, and TB-Biochip. In total, 109 of 238 (45.8 %) specimens were culture-positive for Mycobacterium tuberculosis complex (MTBC), and, of these, 67 isolates were rifampicin resistant (RIF-R) by phenotypic DST and 64/67 (95.5 %) were isoniazid resistant (INH-R). Compared to culture of the same specimen, a single direct Xpert was more sensitive for detecting MTBC [95.3 %, 95 % confidence interval (CI), 90.0–98.3 %] than direct (59.6 %, 95 % CI, 50.2–68.5 %) or concentrated smear (85.3 %, 95 % CI, 77.7–91.1 %) or LJ culture (80.8 %, 95 % CI, 72.4–87.5 %); the specificity was 86.0 % (95 % CI, 78.9–91.3 %). Compared with MGIT DST, Xpert correctly identified 98.2 % (95 % CI, 91.5–99.9 %) of RIF-R and 95.5 % (95 % CI, 85.8–99.2 %) of RIF-susceptible (RIF-S) specimens. In a subset of 104 specimens, the sensitivity of TB-Biochip for MTBC detection compared to culture was 97.3 % (95 % CI, 91.0–99.5 %); the specificity was 78.1 % (95 % CI, 61.5–89.9 %). TB-Biochip correctly identified 100 % (95 % CI, 94.2–100 %) of RIF-R, 94.7 % (95 % CI, 76.7–99.7 %) of RIF-S, 98.2 % (95 % CI, 91.4–99.9 %) of INH-R, and 78.6 % (95 % CI, 52.1–94.2 %) of INH-S specimens compared to MGIT DST. Xpert and Biochip were similar in accuracy for detecting MTBC and RIF resistance compared to conventional culture methods.     

Xpert MTB/RIF for rapid diagnosis of tuberculous lymphadenitis from fine-needle-aspiration biopsy specimens

This study demonstrates the excellent diagnostic accuracy of the Xpert MTB/RIF test in patients with tuberculous lymphadenitis. The test sensitivity and specificity were 96.7% (95% confidence interval [CI], 86.6 to 100%) and 88.9% (95% CI, 69.6 to 100%), respectively, and it correctly identified 6/6 (100%) of the cytology smear-negative/culture-positive cases and 1 of 2 (50%) rifampin-resistant cases.     

Evaluation of Xpert MTB/RIF for Detection of Tuberculosis from Blood Samples of HIV-Infected Adults Confirms Mycobacterium tuberculosis Bacteremia as an Indicator of Poor Prognosis

Tuberculosis (TB) remains a leading cause of death among HIV-infected adults, in part because of delayed diagnosis and therefore delayed initiation of treatment. Recently, the Gene-Xpert platform, a rapid, PCR-based diagnostic platform, has been validated for the diagnosis of TB with sputum. We have evaluated the Xpert MTB/RIF assay for the diagnosis of Mycobacterium tuberculosis bacteremia and investigated its impact on clinical outcomes. Consecutive HIV-infected adults with fever and cough presenting to Queen Elizabeth Central Hospital, Blantyre, Malawi, were recruited and followed up for 2 months. At presentation, three sputum samples were examined by smear, culture, and Xpert MTB/RIF assay for the presence of M. tuberculosis and blood was drawn for PCR with Xpert, for mycobacterial culture (Myco/F Lytic), and for aerobic culture. One hundred four patients were recruited, and 44 (43%) were sputum culture positive for M. tuberculosis. Ten were Xpert blood positive, for a sensitivity of 21% and a specificity of 100%. The 2-week mortality rate was significantly higher among patients who were Xpert blood positive than among those who were negative (40% versus 3%; multivariate odds ratio [OR] for death if positive, 44; 95% confidence interval [CI], 3 to 662). This effect persisted on assessment of the mortality rate at 2 months (40% versus 11%; OR, 5.6; 95% CI, 1.3 to 24.6). When screening uncomplicated patients presenting with a productive cough for pulmonary TB, Xpert blood offers no diagnostic advantage over sputum testing. Despite this, Xpert blood positivity is highly predictive of early death and this test rapidly identifies a group of patients in urgent need of initiation of treatment.     

Evaluation of the Xpert MTB/RIF test accuracy for diagnosis of tuberculosis in areas with a moderate tuberculosis burden

The Xpert MTB/RIF assay (Xpert) is a molecular assay used for direct detection of Mycobacterium tuberculosis (MTB) in clinical specimens. In this study, we aimed to assess the accuracy of the Xpert assay for the diagnosis of tuberculosis (TB) in TB suspected patients from the northern region of Iran. The obtained results were compared with the culture method. The sputum specimens were examined using the Xpert assay, smear microscopy, and solid culture media as a reference diagnostic tool. Among 293 presumptive TB cases, 92 (31.4%) were positive according to the culture method. The Xpert method detected 88 (95.7%) cases that were positive according to the culture method, compared with 78 (84.8%) positive cases according to smear microscopy. The overall sensitivity and specificity of the Xpert method for TB diagnosis were 95.7% and 99%, respectively. Also, the sensitivity and specificity for smear microscopy were 84.8% and 97.5%, respectively. The Xpert assay showed high overall sensitivity and specificity; thus, it can be effectively used for the early and accurate diagnosis of MTB in TB endemic areas. In addition, the agreement between semi‐quantitative results of Xpert and smear microscopy assays could be helpful in evaluating transmission potential in TB patients.     

Discordance between Xpert MTB/RIF Assay and Bactec MGIT 960 Culture System for Detection of Rifampin-Resistant Mycobacterium tuberculosis Isolates in a Country with a Low Tuberculosis (TB) Incidence

Among 452 samples that were positive by the Xpert MTB/RIF (Xpert) assay and MGIT 960 system (MGIT), 440 and 10 Mycobacterium tuberculosis samples were detected as rifampin susceptible and rifampin resistant, respectively. Two isolates that were rifampin susceptible by the MGIT system were rifampin resistant by the Xpert assay. rpoB sequencing identified a silent (CTG521TTG) mutation in one isolate and a missense (GAC516TAC) mutation in another. The detection of rifampin resistance is imperfect with both the Xpert assay and MGIT system. Any discordant rifampin resistance results should be confirmed by sequencing of the rpoB gene.     

GeneXpertMTB/RIF Assay对肺部结核的临床诊断及治疗价值

目的:探究GeneXpertMTB/RIF Assay对临床诊断及治疗肺部结核的应用价值。方法:收集2019年1月至2019年12月在甘孜藏族自治州人民医院住院的肺结核患者的痰液标本148份,同时选取50份非结核肺部感染患者的痰液标本作为对照。分别采用涂片抗酸杆菌检查、MGIT960检测MTB及药敏法和GeneXpertMTB/RIF检测法对痰液标本中的结核分枝杆菌及其耐药性进行测定,并以MGIT960药敏法为标准分析GeneXpertMTB/RIF检测法检测RIF耐药性的敏感性及特异性。结果:GeneXpertMTB/RIF、MGIT960培养法及直接涂片法检测痰液标本中MTB的敏感度分别为60.14%、58.11%、24.32%;特异度分别为100.00%、92.00%和94.00%。GeneXpertMTB/RIF检测法的灵敏度明显高于其他两项检测方法。GeneXpertMTB/RIF检测法与BACTEC MGIT960培养法无统计学差异(X²=0.126,P=0.722),与痰涂片检测结果差异也无统计学意(X²⁼38.899,P=0.000);GeneXpertMTB/RIF检测法检测利福平耐药性的敏感度为100.00%,特异度为95.31%。结论:GeneXpertMTB/RIF检测法的检测速度快、灵敏度高、特异性强,有助于实验室结核分枝杆菌及其耐药性的快速鉴定和筛查,对于临床上对结核病患者的早期诊断和治疗有着非常重要的临床应用意义。     

An automated smear microscopy system to diagnose tuberculosis in a high-burden setting

ObjectivesTB-EASM (Howsome, Shanghai, China), an automated system combining smear preparation, staining and microscopy in a single platform, was evaluated for tuberculosis (TB) diagnosis in a high disease-burden setting.MethodsSputum samples from individuals with pulmonary TB were processed in parallel using conventional manual smear microscopy (MS), TB-EASM, liquid culture and GeneXpert. Method sensitivity and specificity were compared with Mycobacterium tuberculosis detection by mycobacteria growth indicator tube (MGIT) and/or GeneXpert MTB/RIF.ResultsOf 524 samples, 496 met evaluation criteria for study inclusion. The proportion of M. tuberculosis detected by TB-EASM was 28.2% (150/496), significantly higher than for MS (111/496, 21.2%, p 0.01) and comparable to the rate for MGIT (163/496, 32.9%, p > 0.05). For 190 M. tuberculosis-positive cases identified using MGIT and/or GeneXpert MTB/RIF, the reference standard detection methods, TB-EASM detected 140 positive cases, for an overall sensitivity rate of 73.7% (140/190, 95% CI 67.4–79.9), which was significantly higher than for MS (105/190, 55.3%, 95% CI 48.2–62.3, p < 0.01). Specificities were 96.7% (296/306, 95% CI 94.7–98.7) for TB-EASM and 98.0% (300/306, 95% CI 96.5–99.6) for MS.ConclusionTB-EASM outperformed conventional MS for M. tuberculosis detection in sputum specimens.     

Evaluation of Xpert MTB/RIF for Detection of Mycobacterium tuberculosis in Cerebrospinal Fluid

Studies investigating Xpert MTB/RIF diagnostic performance on cerebrospinal fluid (CSF) samples are lacking in resource-rich settings. Xpert MTB/RIF results for 740 CSF samples from 698 patients across England were retrospectively compared with the results of culture of the same and contemporary samples. The overall sensitivity was calculated at 55%.     

Improved Case Detection Using Xpert Mycobacterium tuberculosis/Rifampicin Assay in Skeletal Tuberculosis

Background: In India, musculoskeletal tuberculosis (TB) accounts for 10%–25% of extrapulmonary TB. Data on drug-resistant skeletal TB are lacking. At present, the diagnosis is based mainly on radiological techniques. Laboratory confirmation of skeletal TB is delayed as 6–8 weeks are required for culture results. Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay is a fully automated test which simultaneously detects MTB and RIF resistance within 3 h. Hence, this study was done to compare the yield of case detection using Xpert assay in comparison with culture in specimens received from clinically suspected skeletal TB cases. Methods: Retrospective analysis of microscopy, culture and Xpert assay results was carried out on specimens received in laboratory from skeletal TB cases from January 2016 to December 2017. Results: Of the 201 patients analysed, majority of the specimens were obtained from the spine (55.72%). MTB was detected in 48.68% of tissue and 24% of pus specimens. Xpert assay was detected MTB in 67 (33.33%) specimens of which 53 (47.32%) were from the spine. Culture was detected MTB in 66 (32.83%) specimens. Xpert assay was detected two specimens more than culture. One specimen was positive by only culture. RIF-resistant MTB was detected in 10 (14.92%) specimens by Xpert assay. Conclusion: The spine is the most common site involved. Tissue specimen is better for early diagnosis. High RIF resistance in skeletal TB is an alarming situation. Ability of Xpert MTB/RIF assay for rapid and simultaneous detection of MTB and RIF resistance in comparison with culture makes it a useful diagnostic tool in skeletal TB.     

Integrating the Xpert MTB/RIF Assay into a Diagnostic Workflow for Rapid Detection of Mycobacterium tuberculosis in a Low-Prevalence Area

The Xpert MTB/RIF assay is a rapid and fully automated real-time PCR assay. The performance of the Xpert MTB/RIF assay as a primary screening test for urgent clinical specimens was evaluated during a 2-year period. The results showed that replacing smear microscopy with the Xpert MTB/RIF assay facilitates laboratory handling and improves the sensitivity and specificity of Mycobacterium tuberculosis detection.