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

Utility of Cerebrospinal Fluid Unstimulated Interferon-Gamma (IRISA-TB) as a Same-Day Test for Tuberculous Meningitis in a Tuberculosis-Endemic, Resource-Poor Setting

Background

Tuberculous meningitis (TBM) mortality is high and current diagnostics perform suboptimally. We evaluated the diagnostic performance of a DNA-based assay (GeneXpert Ultra) against a new same-day immunodiagnostic assay that detects unstimulated interferon-gamma (IRISA-TB).

Methods

In a stage 1 evaluation, IRISA-TB was evaluated in biobanked samples from Zambia (n = 82; tuberculosis [TB] and non-TBM), and specificity in a South African biobank (n = 291; non-TBM only). Given encouraging results, a stage 2 evaluation was performed in suspected TBM patients from Zimbabwe and Malawi (n = 668). Patients were classified as having definite, probable or possible TBM, or non-TBM based on their microbiological results, cerebrospinal fluid (CSF) chemistry, and whether they received treatment.

Results

In the stage 1 evaluation, sensitivity and specificity of IRISA-TB were 75% and 87% in the Zambian samples, and specificity was 100% in the South African samples. In the stage 2 validation, IRISA-TB sensitivity (95% confidence interval [CI]) was significantly higher than Xpert Ultra (76.2% [55.0%-89.4%] vs 25% [8.9%-53.3%]; P = .0048) when trace readouts were considered negative. Specificity (95% CI) was similar for both assays (91.4% [88.8%-93.4%] vs 86.9% [83.4%-89.8%]). When the Xpert Ultra polymerase chain reaction product was verified by sequencing, the positive predictive value of trace readouts in CSF was 27.8%. Sensitivity of IRISA-TB was higher in human immunodeficiency virus (HIV)-infected versus uninfected participants (85.8% vs 66.7%).

Conclusions

As a same-day rule-in test, IRISA-TB had significantly better sensitivity than Xpert Ultra in a TB/HIV-endemic setting. An immunodiagnostic approach to TBM is promising, and further studies are warranted.

ISCCM Position Statement on the Approach to and Management of Critically Ill Patients with Tuberculosis

Tuberculosis (TB) is an important cause of morbidity and mortality globally. About 3-4% of hospitalized TB patients require admission to the intensive care unit (ICU); the mortality in these patients is around 50-60%. There is limited literature on the evaluation and management of patients with TB who required ICU admission. The Indian Society of Critical Care Medicine (ISCCM) constituted a working group to develop a position paper that provides recommendations on the various aspects of TB in the ICU setting based on available evidence. Seven domains were identified including the categorization of TB in the critically ill, diagnostic workup, drug therapy, TB in the immunocompromised host, organ support, infection control, and post-TB sequelae. Forty-one questions pertaining to these domains were identified and evidence-based position statements were generated, where available, keeping in focus the critical care aspects. Where evidence was not available, the recommendations were based on consensus. This position paper guides the approach to and management of critically ill patients with TB.

How to cite this article

Chacko B, Chaudhry D, Peter JV, Khilnani G, Saxena P, Sehgal IS, et al. isccm Position Statement on the Approach to and Management of Critically Ill Patients with Tuberculosis. Indian J Crit Care Med 2024;28(S2):S67-S91.

The value of nanopore sequencing as a diagnostic tool in tuberculous meningitis: A protocol of systematic review and meta-analysis

BACKGROUND

Rapid diagnosis of tuberculous meningitis (TBM) remains very difficult. Nanopore sequencing is gaining ground in the field of rapid tuberculosis (TB) diagnostics. The purpose of this study was to complete a protocol to guide the conduct of a systematic review and meta-analysis evaluating the accuracy of nanopore sequencing for the rapid diagnosis of TBM.

METHODS

In accordance with the Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) guidelines, we completed this protocol, which was also registered on the PROSPERO platform. We will search the EMBASE, PubMed, the Cochrane Library, Wanfang database, and China National Knowledge Infrastructure databases for literature that evaluated the accuracy of nanopore sequencing for rapid diagnosis of TBM and screen them according to the inclusion and exclusion criteria, and qualified literature will be extracted with relevant data for further analysis. Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) will be used for evaluating the methodological quality of included studies. Stata (V 15.0; Stata Corp., College Station, TX, the USA) with midas module will be used to perform relevant meta-analysis. Heterogeneity between studies will be assessed by I2 statistics. When significant heterogeneity exists between studies, we will conduct meta-regression analyses, subgroup analyses and sensitivity analyses to further explore the sources of heterogeneity.

CONCLUSION

We completed this study protocol, and this systematic review and meta-analysis will be the first systematic evaluation of the role of nanopore sequencing in the rapid diagnosis of TBM, which will allow clinicians to have a better understanding of the test.

TRIAL REGISTRATION

Systematic review registration PROSPERO Registration number: CRD42024549837.

What is New in the Diagnosis of Childhood Tuberculosis?

The fact that almost half of the 1 million cases of childhood tuberculosis (TB) globally remain undiagnosed jeopardizes the TB elimination goal. Fortunately, there are new advances in this field which have the potential to bridge this diagnostic gap. Advances in imaging include computer assisted interpretation of chest X-rays (CXRs), point of care ultrasound (POCUS) and faster and superior computed tomography/ magnetic resonance imaging (CT/ MRI) protocols. The urine lipoarabinomannan test has proved to be a good point of care test for diagnosing TB in Human immunodeficiency virus (HIV) infected children. Stool and nasopharyngeal aspirates are emerging as acceptable alternatives for gastric lavage and induced sputum for diagnosing intrathoracic tuberculosis. Xpert MTB/RIF Ultra has improved sensitivity compared to Xpert MTB/RIF for diagnosing both pulmonary/ extrapulmonary TB. Xpert XDR is another commercially available accurate point of care test for detecting resistance to drugs other than rifampicin in smear positive samples. Other molecular methods including new line probe assays, pyrosequencing, whole genome sequencing, and targeted next generation sequencing are extremely promising but not available commercially at present. The C-Tb skin test is an acceptable alternative to the tuberculin skin test and interferon gamma release assays for diagnosis of latent infection. There is an urgent need to incorporate some of these advances in the existing diagnostic algorithms of childhood TB.

Diagnostic validity of MRI for central nervous system tuberculosis: protocol for a systematic review and meta-analysis

INTRODUCTION

Central nervous system tuberculosis (CNSTB) is a severe condition, sometimes associated with a poor prognosis. Early diagnosis of CNSTB remains challenging, considering that conventional methods lack sensitivity or might lead to certain side effects. Herein, we presented a protocol for a systematic review and meta-analysis to assess the diagnostic efficacy of MRI for CNSTB.

METHODS AND ANALYSIS

SinoMed, Wanfang database, China National Knowledge Infrastructure, Embase, the Cochrane Library and PubMed will be searched to identify studies reporting on the use of MRI in the diagnosis of CNSTB from database inception to December 2023. The following keywords will be applied: 'Intracranial tuberculosis', 'Cerebral tuberculosis', 'Central nervous system tuberculosis', 'Spinal tuberculous arachnoiditis' and 'Magnetic Resonance Imaging'. Studies that evaluate the diagnostic accuracy of MRI for the diagnosis of CNSTB and report clear reference criteria will be included. Studies from which full true positive, false positive, false negative and true negative values cannot be extracted, those published in languages other than English or Chinese, abstracts not reporting the full text, and case reports will be excluded. Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) will be used to evaluate the methodological quality of each included study. Stata V.15.0 and RevMan V.5.3 will be used to perform a meta-analysis and generate forest plots and summary receiver operating characteristic curves. In case of significant heterogeneity between studies, possible sources of heterogeneity will be explored through subgroup and meta-regression analyses.

ETHICS AND DISSEMINATION

This research is based on public databases and does not require ethical approval. Results will be submitted for publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023415690.

Diagnosis and Management of Tuberculous Meningitis in Children- an Update

UPDATE ON THE DIAGNOSIS AND MANAGEMENT OF TUBERCULOUS MENINGITIS IN CHILDREN: Ronald van Toorn, Regan Solomons Seminars in Pediatric Neurology Volume 21, Issue 1, March 2014, Pages 12-18 Tuberculous meningitis (TBM), the most devastating manifestation of tuberculosis, is often missed or overlooked because of nonspecific symptoms and difficulties in diagnosis. It continues to be an important cause of neurologic handicap in resource-poor countries. Owing to the suboptimal performance of diagnostic tests of TBM, diagnosis relies on thorough history, clinical examination, and relevant investigations. The development of affordable, accurate diagnostic tests for TBM in resource-poor settings remains a priority. Short intensified treatment is safe and effective in both human immunodeficiency virus (HIV)-infected and HIV-uninfected children. Treatment of tuberculous hydrocephalus depends on the level of the cerebrospinal fluid obstruction. Corticosteroids reduce risk of neurodisability and death in HIV-uninfected children. Thalidomide should be considered in children compromised by tuberculosis abscesses and tuberculous-related optochiasmic arachnoiditis. In resource-poor countries, home-based TBM treatment after initial in-hospital stabilization is feasible in carefully selected patients. Early diagnosis and treatment of TBM is the single most important factor determining outcome.

A systematic review and meta-analysis of the diagnostic accuracy of metagenomic next-generation sequencing for diagnosing tuberculous meningitis

Objective

The utility of metagenomic next-generation sequencing (mNGS) in the diagnosis of tuberculous meningitis (TBM) remains uncertain. We performed a meta-analysis to comprehensively evaluate its diagnostic accuracy for the early diagnosis of TBM.

Methods

English (PubMed, Medline, Web of Science, Cochrane Library, and Embase) and Chinese (CNKI, Wanfang, and CBM) databases were searched for relevant studies assessing the diagnostic accuracy of mNGS for TBM. Review Manager was used to evaluate the quality of the included studies, and Stata was used to perform the statistical analysis.

Results

Of 495 relevant articles retrieved, eight studies involving 693 participants (348 with and 345 without TBM) met the inclusion criteria and were included in the meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and area under the summary receiver-operating characteristic curve of mNGS for diagnosing TBM were 62% (95% confidence interval [CI]: 0.46-0.76), 99% (95% CI: 0.94-1.00), 139.08 (95% CI: 8.54-2266), 0.38 (95% CI: 0.25-0.58), 364.89 (95% CI: 18.39-7239), and 0.97 (95% CI: 0.95-0.98), respectively.

Conclusions

mNGS showed good specificity but moderate sensitivity; therefore, a more sensitive test should be developed to assist in the diagnosis of TBM.

Diagnosis of extrapulmonary tuberculosis by GeneXpert MTB/RIF Ultra assay

INTRODUCTION

Diagnosis of extrapulmonary tuberculosis (EPTB) is an arduous task owing to different anatomical locations, unusual clinical presentations, and sparse bacillary load in clinical specimens. Although GeneXpert® MTB/RIF is a windfall in TB diagnostics including EPTB, it yields low sensitivities but high specificities in many EPTB specimens. To further improve the sensitivity of GeneXpert®, GeneXpert® Ultra, a fully nested real-time PCR targeting IS6110, IS1081 and rpoB (Rv0664) has been endorsed by the WHO (2017), wherein melt curve analysis is utilized to detect rifampicin-resistance (RIF-R).

AREA COVERED

We described the assay chemistry/work design of Xpert Ultra and evaluated its performance in several EPTB types, that is, TB lymphadenitis, TB pleuritis, TB meningitis, and so on, against the microbiological reference standard or composite reference standard. Notably, Xpert Ultra exhibited better sensitivities than Xpert, but mostly at the compensation of specificity values. Moreover, Xpert Ultra exhibited low false-negative and false-positive RIF-R results, compared with Xpert. We also detailed other molecular tests, that is, Truenat MTBTM/TruPlus, commercial real-time PCR, line probe assay, and so on, for EPTB diagnosis.

EXPERT OPINION

A combination of clinical features, imaging, histopathological findings, and Xpert Ultra are adequate for definite EPTB diagnosis so as to initiate an early anti-tubercular therapy.

Specificities of Meningitis and Meningo-Encephalitis After Kidney Transplantation: A French Retrospective Cohort Study

Kidney transplant recipients develop atypical infections in their epidemiology, presentation and outcome. Among these, meningitis and meningoencephalitis require urgent and adapted anti-infectious therapy, but published data is scarce in KTRs. The aim of this study was to describe their epidemiology, presentation and outcome, in order to improve their diagnostic and management. We performed a retrospective, multicentric cohort study in 15 French hospitals that included all 199 cases of M/ME in KTRs between 2007 and 2018 (0.9 case per 1,000 KTRs annually). Epidemiology was different from that in the general population: 20% were due to Cryptococcus neoformans, 13.5% to varicella-zoster virus, 5.5% to Mycobacterium tuberculosis, and 4.5% to Enterobacteria (half of which produced extended spectrum beta-lactamases), and 5% were Post Transplant Lymphoproliferative Disorders. Microorganisms causing M/ME in the general population were infrequent (2%, for Streptococcus pneumoniae) or absent (Neisseria meningitidis). M/ME caused by Enterobacteria, Staphylococci or filamentous fungi were associated with high and early mortality (50%-70% at 1 year). Graft survival was not associated with the etiology of M/ME, nor was impacted by immunosuppression reduction. Based on these results, we suggest international studies to adapt guidelines in order to improve the diagnosis and the probabilistic treatment of M/ME in SOTRs.

Diagnostic accuracy of nanopore sequencing using respiratory specimens in the diagnosis of pulmonary tuberculosis

OBJECTIVES

The aim of this study was to assess the role of nanopore sequencing using respiratory specimens in the early diagnosis of pulmonary tuberculosis (PTB) and simultaneously compare it head-to-head with Mycobacterium tuberculosis (MTB) culture, and Xpert MTB/rifampin (RIF).

METHODS

The clinical data of 164 patients with suspected PTB were retrospectively reviewed to determine the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of the acid-fast bacilli (AFB) smear, MTB culture, Xpert MTB/RIF, and nanopore sequencing and assess their diagnostic accuracy compared with culture combined with clinical diagnosis.

RESULTS

The overall sensitivity, specificity, PPV, NPV, and AUC of the AFB smear were 27.6%, 87.5%, 84.2%, 33.3%, and 0.58, respectively; for MTB culture, these values were 57.8%, 100.0%, 100.0%, 49.5%, and 0.79, respectively; for Xpert MTB/RIF, these values were 62.9%, 97.9%, 98.7%, 52.2%, and 0.80, respectively; and for nanopore sequencing, these values were 94.8%, 97.9%, 99.1%, 88.7%, and 0.96, respectively.

CONCLUSION

The diagnostic accuracy of nanopore sequencing was excellent in terms of PTB diagnosis and was considerably better than that of the Xpert MTB/RIF and MTB culture. Nanopore sequencing could be an effective alternative to Xpert MTB/RIF for the initial detection of PTB to improve the accuracy of PTB diagnosis.