Impact of systematic early tuberculosis detection using Xpert MTB/RIF Ultra in children with severe pneumonia in high tuberculosis burden countries (TB-Speed pneumonia): a stepped wedge cluster randomized trial

Xpert-Ultra Assay in Stool and Urine Samples to Improve Tuberculosis Diagnosis in Children: The Médecins Sans Frontières Experience in Guinea-Bissau and South Sudan

Background

More than half of childhood tuberculosis cases remain undiagnosed yearly. The World Health Organization recommends the Xpert-Ultra assay as a first pediatric diagnosis test, but microbiological confirmation remains low. We aimed to determine the diagnostic performance of Xpert-Ultra with stool and urine samples in presumptive pediatric tuberculosis cases in 2 high-tuberculosis-burden settings.

Methods

This Médecins Sans Frontières cross-sectional multicentric study took place at Simão Mendes Hospital, Guinea-Bissau (July 2019 to April 2020) and in Malakal Hospital, South Sudan (April 2021 to June 2023). Children aged 6 months to 15 years with presumptive tuberculosis underwent clinical and laboratory assessment, with 1 respiratory and/or extrapulmonary sample (reference standard [RS]), 1 stool, and 1 urine specimen analyzed with Xpert-Ultra.

Results

A total of 563 children were enrolled in the study, 133 from Bissau and 400 from Malakal; 30 were excluded. Confirmation of tuberculosis was achieved in 75 (14.1%), while 248 (46.5%) had unconfirmed tuberculosis. Of 553 with an RS specimen, the overall diagnostic yield was 12.4% (66 of 533). A total of 493 stool and 524 urine samples were used to evaluate the performance of Xpert-Ultra with these samples. Compared with the RS, the sensitivity and specificity of Xpert-Ultra were 62.5% (95% confidence interval, 49.4%-74%) and 98.3% (96.7%-99.2%), respectively, with stool samples, and 13.9% (7.5%-24.3%) and 99.4% (98.1%-99.8%) with urine samples. Nine patients were positive with stool and/or urine samples but negative with the RS.

Conclusions

Xpert-Ultra in stool samples showed moderate to high sensitivity and high specificity compared with the RS and an added diagnostic yield when RS results were negative. Xpert-Ultra in stool samples was useful in extrapulmonary cases. Xpert-Ultra in urine samples showed low test performance.

Clinical Trials Registration

NCT06239337.

Xpert MTB/RIF Ultra Assay Using Stool: an Effective Solution for Bacilli Identification from Adult Pulmonary Tuberculosis Suspects without Expectorated Sputum

This study evaluated the diagnostic performance of stool-based Xpert MTB/RIF Ultra assay (Xpert-Ultra, Cepheid, USA) against other tests using respiratory tract specimens (RTS) and stool for diagnosing adult pulmonary tuberculosis. A prospective study on patients with presumptive pulmonary tuberculosis was conducted in Beijing Chest Hospital from June to November 2021. The smear test, MGIT960 liquid culture, and Xpert MTB/RIF (Xpert, Cepheid, USA) were performed simultaneously on RTS, and smear, culture Xpert, and Xpert-Ultra were performed simultaneously using stool. Patients were grouped based on the outcomes of RTS examination and other tests. In total, 130 eligible patients were enrolled that included 96 pulmonary tuberculosis and 34 non-TB patients. The sensitivity of smear, culture, Xpert, and Xpert-Ultra using stool was 10.96%, 23.28%, 60.27%, and 79.45%, respectively. The specificities of Xpert and Xpert-Ultra using RTS and stool were all 100% (34/34). Notably, all five confirmed cases detected by bronchoalveolar lavage fluid (BALF) examination yielded Xpert-Ultra positive outcomes with the stool specimens. Xpert-Ultra assay on stool sample harbors comparable sensitivity with Xpert on RTS. Thus, the Xpert-Ultra testing on stool specimens could be a very promising and practical strategy to improve pulmonary tuberculosis (PTB) diagnosis, especially among patients who could not expectorate sputum. IMPORTANCE This study is aimed at assessing the value of Xpert MTB/RIF Ultra (Xpert-Ultra) in PTB on stool in adult in low HIV settings and Xpert-Ultra assay on stool sample harboring comparable sensitivity with Xpert MTB/RIF on respiratory tract specimens. Although the yield in stool samples by Xpert-Ultra is lower than RTS, it may be useful in detecting disease in presumptive TB patients who cannot expectorate sputum and are not open to BALF collection. In addition, Xpert-Ultra with a "trace call" on stool in adult was highly supportive of PTB.

Rapid and Accurate Diagnosis of Pediatric Tuberculosis Disease: A Diagnostic Accuracy Study for Pediatric Tuberculosis

INTRODUCTION

An estimated 1.2 million children develop tuberculosis (TB) every year with 240,000 dying because of missed diagnosis. Existing tools suffer from lack of accuracy and are often unavailable. Here, we describe the scientific and clinical methodology applied in RaPaed-TB, a diagnostic accuracy study.

METHODS

This prospective diagnostic accuracy study evaluating several candidate tests for TB was set out to recruit 1000 children <15 years with presumptive TB in 5 countries (Malawi, Mozambique, South Africa, Tanzania, India). Assessments at baseline included documentation of TB signs and symptoms, TB history, radiography, tuberculin skin test, HIV testing and spirometry. Respiratory samples for reference standard testing (culture, Xpert Ultra) included sputum (induced/spontaneous) or gastric aspirate, and nasopharyngeal aspirate (if <5 years). For novel tests, blood, urine and stool were collected. All participants were followed up at months 1 and 3, and month 6 if on TB treatment or unwell. The primary endpoint followed NIH-consensus statements on categorization of TB disease status for each participant. The study was approved by the sponsor's and all relevant local ethics committees.

DISCUSSION

As a diagnostic accuracy study for a disease with an imperfect reference standard, Rapid and Accurate Diagnosis of Pediatric Tuberculosis Disease (RaPaed-TB) was designed following a rigorous and complex methodology. This allows for the determination of diagnostic accuracy of novel assays and combination of testing strategies for optimal care for children, including high-risk groups (ie, very young, malnourished, children living with HIV). Being one of the largest of its kind, RaPaed-TB will inform the development of improved diagnostic approaches to increase case detection in pediatric TB.

Effect of systematic tuberculosis detection on mortality in young children with severe pneumonia in countries with high incidence of tuberculosis: a stepped-wedge cluster-randomised trial

BACKGROUND

Tuberculosis diagnosis might be delayed or missed in children with severe pneumonia because this diagnosis is usually only considered in cases of prolonged symptoms or antibiotic failure. Systematic tuberculosis detection at hospital admission could increase case detection and reduce mortality.

METHODS

We did a stepped-wedge cluster-randomised trial in 16 hospitals from six countries (Cambodia, Cameroon, Côte d'Ivoire, Mozambique, Uganda, and Zambia) with high incidence of tuberculosis. Children younger than 5 years with WHO-defined severe pneumonia received either the standard of care (control group) or standard of care plus Xpert MTB/RIF Ultra (Xpert Ultra; Cepheid, Sunnyvale, CA, USA) on nasopharyngeal aspirate and stool samples (intervention group). Clusters (hospitals) were progressively switched from control to intervention at 5-week intervals, using a computer-generated random sequence, stratified on incidence rate of tuberculosis at country level, and masked to teams until 5 weeks before switch. We assessed the effect of the intervention on primary (12-week all-cause mortality) and secondary (including tuberculosis diagnosis) outcomes, using generalised linear mixed models. The primary analysis was by intention to treat. We described outcomes in children with severe acute malnutrition in a post hoc analysis. This study is registered with ClinicalTrials.gov (NCT03831906) and the Pan African Clinical Trial Registry (PACTR202101615120643).

FINDINGS

From March 21, 2019, to March 30, 2021, we enrolled 1401 children in the control group and 1169 children in the intervention group. In the intervention group, 1140 (97·5%) children had nasopharyngeal aspirates and 942 (80·6%) had their stool collected; 24 (2·1%) had positive Xpert Ultra. At 12 weeks, 110 (7·9%) children in the control group and 91 (7·8%) children in the intervention group had died (adjusted odds ratio [OR] 0·986, 95% CI 0·597-1·630, p=0·957), and 74 (5·3%) children in the control group and 88 (7·5%) children in the intervention group had tuberculosis diagnosed (adjusted OR 1·238, 95% CI 0·696-2·202, p=0·467). In children with severe acute malnutrition, 57 (23·8%) of 240 children in the control group and 53 (17·8%) of 297 children in the intervention group died, and 36 (15·0%) of 240 children in the control group and 56 (18·9%) of 297 children in the intervention group were diagnosed with tuberculosis. The main adverse events associated with nasopharyngeal aspirates were samples with blood in 312 (27·3%) of 1147 children with nasopharyngeal aspirates attempted, dyspnoea or SpO₂ less than 95% in 134 (11·4%) of children, and transient respiratory distress or SpO₂ less than 90% in 59 (5·2%) children. There was no serious adverse event related to nasopharyngeal aspirates reported during the trial.

INTERPRETATION

Systematic molecular tuberculosis detection at hospital admission did not reduce mortality in children with severe pneumonia. High treatment and microbiological confirmation rates support more systematic use of Xpert Ultra in this group, notably in children with severe acute malnutrition.

FUNDING

Unitaid and L'Initiative.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Alert sign and symptoms for the early diagnosis of pulmonary tuberculosis: analysis of patients followed by a tertiary pediatric hospital

Background

Intercepting earlier suspected TB (Tuberculosis) cases clinically is necessary to reduce TB incidence, so we described signs and symptoms of retrospective cases of pulmonary TB and tried to evaluate which could be early warning signs.

Methods

We conducted a retrospective descriptive study of pulmonary TB cases in children in years 2005–2017; in years 2018–2020 we conducted a cohort prospective study enrolling patients < 18 years accessed to Emergency Department (ED) with signs/symptoms suggestive of pulmonary TB.

Results

In the retrospective analysis, 226 patients with pulmonary TB were studied. The most frequently described items were contact history (53.5%) and having parents from countries at risk (60.2%). Cough was referred in 49.5% of patients at onset, fever in 46%; these symptoms were persistent (lasting ≥ 10 days) in about 20%. Lymphadenopathy is described in 15.9%. The prospective study enrolled 85 patients of whom 14 (16.5%) were confirmed to be TB patients and 71 (83.5%) were non-TB cases. Lymphadenopathy and contact history were the most correlated variables. Fever and cough lasting ≥ 10 days were less frequently described in TB cases compared to non-TB patients (p < 0.05).

Conclusions

In low TB endemic countries, pulmonary TB at onset is characterized by different symptoms, i.e. persistent fever and cough are less described, while more relevant are contact history and lymphadenopathy. It was not possible to create a score because signs/symptoms usually suggestive of pulmonary TB (considered in the questionnaire) were not significant risk factors in our reality, a low TB country.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-022-01288-5.

Diagnostic Advances in Childhood Tuberculosis—Improving Specimen Collection and Yield of Microbiological Diagnosis for Intrathoracic Tuberculosis

There is no microbiological gold standard for childhood tuberculosis (TB) diagnosis. The paucibacillary nature of the disease, challenges in sample collection in young children, and the limitations of currently available microbiological tests restrict microbiological confirmation of intrathoracic TB to the minority of children. Recent WHO guidelines recommend the use of novel rapid molecular assays as initial diagnostic tests for TB and endorse alternative sample collection methods for children. However, the uptake of these tools in high-endemic settings remains low. In this review, we appraise historic and new microbiological tests and sample collection techniques that can be used for the diagnosis of intrathoracic TB in children. We explore challenges and possible ways to improve diagnostic yield despite limitations, and identify research gaps to address in order to improve the microbiological diagnosis of intrathoracic TB in children.