Evaluation of Xpert MTB/RIF Ultra assay for rapid diagnosis of pulmonary and extra-pulmonary tuberculosis in an Italian center

Diagnostic accuracy of Xpert MTB/RIF Ultra for detecting pulmonary tuberculosis and rifampicin resistance: a systematic review and meta-analysis

BACKGROUND

Public health issues related to tuberculosis still exist. Because Xpert MTB/RIF Ultra is more effective than conventional TB diagnostic techniques are, it is now regarded as an emerging technology. The diagnostic accuracy of Xpert MTB/RIF Ultra for tuberculosis was assessed in this systematic study.

METHODS

We searched the PubMed, Cochrane, EMBASE, and Web of Science databases for pertinent literature published before January 18, 2024. The quality of the collected literature was assessed via Review Manager 5.3 software, which applies the quality assessment of diagnostic accuracy studies criteria. Using Metadisc 1.40 software, the sensitivity, specificity, and summary receiver operating characteristic curves were plotted and examined. Stata 12.0 was the program we utilized to assess publication bias in this investigation. The Prospero prospective register of systematic reviews included this study (reference number CRD42024569674).

RESULTS

Analysis of 187 fourfold tables from 72 studies revealed that Xpert MTB/RIF Ultra demonstrated an overall pooled sensitivity of 76% and specificity of 95% for detecting pulmonary tuberculosis. The positive likelihood ratio (PLR) was 14.91, and the negative likelihood ratio (NLR) was 0.23, with an area under the curve (AUC) of 0.9351 and a diagnostic odds ratio (DOR) of 73.39. For detecting rifampin resistance, the combined sensitivity and specificity were 94% and 97%, respectively. The pooled PLR was 24.94, the NLR was 0.07, and the DOR was 429.05. The area under the summary receiver operating characteristic (SROC) curve was 0.9868.

CONCLUSION

In conclusion, developing effective laboratory diagnostic tools for identifying Mycobacterium tuberculosis is essential for epidemiological research. This study demonstrated that Xpert MTB/RIF Ultra effectively diagnosed Mycobacterium tuberculosis infection, including pulmonary tuberculosis, as well as rifampin resistance, highlighting its potential as a valuable tool for both diagnosis and resistance detection.

Evaluation of Xpert MTB/RIF Ultra for the Diagnosis of Extrapulmonary Tuberculosis: A Retrospective Analysis in Saudi Arabia

The incidence of extrapulmonary tuberculosis (EPTB) in low- and middle-income countries, as well as, high-income countries has increased over the last two decades. The acid-fast bacillus (AFB) smear test is easy to perform and cost-effective with a quick turnaround time but the test has low sensitivity. Culture remains the gold standard for detecting TB; however, it has low sensitivity and slow bacterial growth patterns, as it may take up to 6 to 8 weeks to grow. Therefore, a rapid detection tool is crucial for the early initiation of treatment and ensuring an improved therapeutic outcome. Here, the Xpert Ultra system was developed as a nucleic acid amplification technique to accelerate the detection of MTB in paucibacillary clinical samples and endorsed by the World Health Organization. From March 2020 to August 2021, Xpert Ultra was evaluated for its sensitivity and specificity against EPTB and compared with those of the routinely used Xpert, culture, and AFB tests in 845 clinical samples in Saudi Arabia. The results indicate the overall sensitivity and specificity of Xpert Ultra to be 91% and 95%, respectively, compared with the Xpert (82% and 99%, respectively) and AFB smear (18% and 100%, respectively) tests. The results also indicated that despite the low microbial loads that were categorized as trace, very low, or low on Xpert Ultra, yet, complete detection was achieved with some sample types (i.e., 100% detection). Consequently, Xpert Ultra has great potential to replace conventional diagnostic approaches as a standard detection method for EPTB.

Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation

The aim of this study was to evaluate the performance of Xpert MTB/RIF Ultra (Ultra) compared with its predecessor, Xpert MTB/RIF (Xpert), in the diagnosis of tuberculosis (TB) in a low TB incidence country. Retrospective analysis was performed on 689 clinical samples received between 2015 and 2018, on which Xpert was performed, and on 715 samples, received between 2018 and 2020, on which Ultra was performed. Samples were pulmonary (n = 830) and extrapulmonary (n = 574) in nature, and a total of 264 were culture positive for Mycobacterium tuberculosis complex (MTBC). The diagnostic performance of both assays was analyzed using culture as the reference standard. The sensitivity of Ultra for culture positive (smear positive and smear negative) MTBC samples, was 93.2% (110/118) compared with 82.2% (120/146) for Xpert (P = 0.0078). In smear negative-culture positive samples, Ultra had a sensitivity of 74.2% (23/31) versus 36.11% (13/36) for Xpert (P = 0.0018). Specificity of both assays was comparable at 94.8% (566/597) for Ultra and 95.8% (520/543) for Xpert (P = 0.4475). The sensitivity of Ultra and Xpert assays among exclusively pulmonary samples was 95.3% (82/86) and 90.3% (84/93), respectively (P = 0.1955), and 87.5% (28/32) and 67.9% (36/53), respectively, among extrapulmonary samples (P = 0.0426). Ultra showed improved performance compared with Xpert in a low TB incidence setting, particularly in smear negative and extrapulmonary MTBC disease. The specificity of Ultra was lower than Xpert, however, this was not statistically significant. IMPORTANCE The study demonstrates the improved sensitivity of the Ultra compared with the Xpert, particularly in smear negative TB disease, for both pulmonary and extrapulmonary samples in a low TB incidence setting. Cycle threshold (Ct) value for both assays was found to positively correlate with time to TB culture positivity, suggesting that Ct and semiquantitative results could be used as indicators of sample MTBC bacillary burden, and thus, perhaps, of transmission potential. This may have implications for the designation of patient isolation precautions.

Rapid Molecular Diagnosis of Extra-Pulmonary Tuberculosis by Xpert/RIF Ultra

Rapid detection of Mycobacterium tuberculosis complex and determination of drug resistance are essential for early diagnosis and treatment of tuberculosis (TB). Xpert MTB/RIF Ultra (Xpert Ultra), a molecular test that can simultaneously identify M. tuberculosis complex and resistance to rifampicin directly on clinical samples, is currently used. Xpert Ultra represents a helpful tool for rapid pulmonary TB diagnosis, especially in patients with paucibacillary infection. The aim of this review is to provide an overview of the diagnostic performance of Xpert Ultra in detection of extra-pulmonary tuberculosis.

Head-to-head comparison of the efficacy of Xpert MTB/RIF Ultra and Xpert MTB/RIF for the diagnosis of tuberculous pleurisy: A systematic review and meta-analysis

BACKGROUND

The aim of this study was to evaluate the diagnostic accuracy of Xpert MTB/RIF Ultra (Xpert Ultra) and Xpert MTB/RIF (Xpert) for the diagnosis of tuberculous pleurisy (TBP) head-to-head using meta-analysis method.

METHODS

On May 12, 2021, we searched multiple databases for reports that used Xpert Ultra and Xpert for TBP diagnosis head-to-head and screened eligible studies for inclusion. Accuracy of Xpert Ultra and Xpert were compared to that of the composite reference standard (CRS) and culture. When heterogeneity was evident, sources of heterogeneity were explored using subgroup analyses, sensitivity analysis, and meta-regression analyses.

RESULTS

Five articles met the inclusion criteria for meta-analysis. When results from different specimens or different reference standards were reported in the same article, we analyzed them as separate studies. Thus, 6 studies compared Xpert Ultra and Xpert with CRS, 5 studies compared Xpert Ultra and Xpert with culture. Pooled sensitivity and specificity of Xpert Ultra were 52% and 98% compared to CRS, and 82% and 77% compared to culture. Pooled sensitivity and specificity of Xpert were 22% and 99% compared to CRS, and 48% and 94% compared to culture. Significant heterogeneity in sensitivity was observed compared to CRS.

CONCLUSION

The sensitivity of Xpert Ultra was moderate but better than that of the Xpert; however, its specificity was lower. The role of Xpert Ultra and Xpert in the early and rapid diagnosis of TBP was limited.

Efficacy of Xpert MTB/RIF Ultra in diagnosing tuberculosis meningitis: A systematic review and meta-analysis

BACKGROUND

This study aimed to assess whether Xpert MTB/RIF Ultra (Xpert Ultra) can effectively diagnose tuberculosis meningitis (TBM) and to simultaneously compare its effectiveness with Xpert in diagnosing TBM in the same population.

METHODS

On August 12, 2020, Wanfang Database, China National Knowledge Infrastructure, Embase, Cochrane Library, and PubMed were searched for studies evaluating the diagnostic accuracy of Xpert Ultra for TBM. Then, we assessed the efficacy of Xpert Ultra against a composite reference standard and culture. If applicable, we also examined the diagnostic efficacy of Xpert in the same population. Heterogeneity was then explored by meta-regression, subgroup, and sensitivity analyses.

RESULTS

Six studies containing 601 specimens reported the diagnostic efficacy of Xpert Ultra for TBM, with a composite reference standard. No study had compared the efficacy between Xpert Ultra and culture. The pooled sensitivity of Xpert Ultra was 64% (95% confidence interval [CI]: 45-80), and the I2 value was 86% (95% CI: 76-96); its specificity for TBM was consistently 100%. In the same population, 5 studies compared the diagnostic efficacy between Xpert Ultra and Xpert for TBM. The pooled sensitivity of Xpert Ultra and Xpert was 68% (95% CI: 46-84; I2 = 87%) and 37% (95% CI: 25-50; I2 = 72%), respectively. The studies were significantly heterogeneous in terms of sensitivity but not heterogeneous in specificity.

CONCLUSIONS

Xpert Ultra was more sensitive than Xpert, but both were specific (100%). Therefore, Xpert Ultra had an excellent diagnostic efficacy for TBM, and it could be the preferred initial test for TBM.

Diagnosis of Osteoarticular Tuberculosis: Perceptions, Protocols, Practices, and Priorities in the Endemic and Non-Endemic Areas of the World-A WAIOT View

There has been a major resurgence of tuberculosis (TB) and drug-resistant tuberculosis in the last few decades. Although it has been brought under control in most Western countries, it is still a major cause of death in endemic regions like India. Osteoarticular tuberculosis (OA TB) forms a small proportion of the total cases of tuberculosis. Perceptions and practices of orthopedic surgeons are entirely different in endemic and non-endemic regions around the world, due to the vast difference in exposure. Literature from endemic areas puts stress on clinico-radiological diagnosis and empirical anti-tubercular treatment (ATT). Such practices, although non-invasive, simple to implement, and economical, carry a significant risk of missing TB mimics and developing drug resistance. However, OA TB is still perceived as a “diagnostic enigma” in non-endemic regions, leading to a delay in diagnosis. Hence, a high index of suspicion, especially in a high-risk population, is needed to improve the diagnosis. Evolving drug resistance continues to thwart efforts to control the disease globally. This review article discusses the perceptions and practices in different parts of the world, with India as an example of the endemic world, and lays down priorities for overcoming the challenges of diagnosing osteoarticular TB.