Xpert MTB/RIF Ultra assay for tuberculosis disease and rifampicin resistance in children

Higher prevalence of pulmonary tuberculosis revealed by Xpert MTB/RIF ultra among drug users in Kinshasa, Democratic Republic of Congo

INTRODUCTION

The Democratic Republic of Congo (DRC) is one of the eight countries with the highest burden of tuberculosis (TB) in the world. The public health system is inadequate and the screening for TB in the key and vulnerable population (KVP), including drug users (DU) is not currently done. The present study aimed to determine the prevalence of pulmonary TB among DU in Kinshasa by comparing molecular tests with microscopic techniques.

METHODS

A cross-sectional study covering 22 townships (out of 24) of Kinshasa was conducted from October to December 2023. Sputum samples were collected from DUs aged ≥ 18 years, clinically suspected of TB, and attending drug consumption sites. The samples were analyzed by both the Acid-fast bacilli (AFB)-Nelseen hot staining and Xpert MTB/RIF Ultra for TB and rifampin-resistance diagnosis.

RESULTS

For 399 DUs included in the study, the age range was from 18 to 77 years old, with a median of 31 (IQR: 25-39). Among these DUs, 359 (89%; 95% CI: 86.64- 92.55%) were male. TB prevalence was 3.5% (95% CI: 1.9-5.8%) when the AFB-Nelseen hot staining was used for diagnosis. However, the prevalence was significantly higher at 13.8% (95% CI: 10.6-17.6%) with the Xpert MTB/RIF test (p = 0.000). Xpert MTB-RIF Ultra contributed with an added value of 82% (95% IC: 79.25- 86.47%) to the diagnosis of TB in DUs. The KAPPA test showed a low concordance at 25%. Alcohol, diazepam and tobacco consumption have been identified as practical risks associated with the onset of pulmonary TB (p < 0.05).

CONCLUSION

DUs are a population at risk of TB that should not be neglected among all KVPs in Kinshasa. In this specific population, the determination of TB prevalence was significantly improved with the use of Xpert MTB/RIF Ultra compared to hot AFB-Neelsen staining. Among the DU included in the present study, those who habitually consumed alcohol in its different forms, diazepam for non-medical purposes, and tobacco, were significantly more infected than the others. DUs should be considered for systemic screening for pulmonary TB alongside other key populations such as people living with HIV and Xpert should be maintained as a first-line test instead of microscopy. Further studies also including asymptomatic participants are needed to assess the burden due to pulmonary TB in DUs as well as in their living environment.

Diagnostic contribution of GeneXpert Ultra in pediatric pulmonary tuberculosis

OBJECTIVES

To evaluate the contribution of Ultra to the diagnosis of pediatric pulmonary tuberculosis (PTB).

METHODS

We analyzed prospective data from children and adolescents with presumed PTB whose specimens were tested with Ultra between January 2020 and December 2022. Diagnosis was based on clinical-radiological criteria, clinical response after a two-month treatment period, and microbiological analysis. Ultra was considered positive with a result of 'Detected' and 'Traces' in children under 10 years and in HIV-infected individuals. Fisher's exact test was used for group comparisons, and McNemar's test was used to compare Ultra results with the diagnostic presumption. The study was approved by the Ethics Committee (CAAE No. 02173518.2.0000.5264).

RESULTS

A total of 41 patients were included, of whom 63% (26/41) were diagnosed with PTB. Among these, 9/26 (34%) had positive results only through Ultra, with negative AFB and culture. The sensitivity and specificity of Ultra were 50% (13/26) and 100% (15/15), respectively. The PPV was 100% (13/13), and the NPV was 54% (15/28). Of these 28 (68%) patients with negative Ultra results, 13 (46%) were diagnosed with PTB, mostly by MoH-SS. Considering culture as the reference, the PPV and NPV were 67% and 100%, respectively.

CONCLUSIONS

Ultra significantly contributed to the diagnosis of pediatric PTB, proving to be a promising tool for paucibacillary forms of the disease. However, it should not be used alone. Integrating laboratory tests with clinical evaluation is essential to improving diagnostic accuracy and the management of pediatric TB.

Truenat MTB assays for pulmonary tuberculosis and rifampicin resistance in adults and adolescents

BACKGROUND

Accurate and rapid diagnosis is crucial for ending the tuberculosis epidemic. Truenat assays are World Health Organization (WHO)-recommended rapid molecular diagnostic tests that detect Mycobacterium tuberculosis complex and rifampicin resistance.

OBJECTIVES

Primary objective To assess the diagnostic accuracy of Truenat assays (MTB, MTB Plus, and MTB-RIF Dx) for detecting pulmonary tuberculosis and rifampicin resistance in adults and adolescents with presumptive pulmonary tuberculosis. Secondary objectives To compare the diagnostic accuracy of Truenat assays and Xpert MTB/RIF Ultra for detecting pulmonary tuberculosis and rifampicin resistance and to investigate potential sources of heterogeneity (e.g. HIV status and smear status).

SEARCH METHODS

We searched MEDLINE, Embase, Science Citation Index and Biosis previews, Global Index Medicus, SCOPUS, WHO ICTRP, and ClinicalTrials.gov for published articles and trials in progress on 16and 17 October 2023. We searched ProQuest Dissertations & Theses A&I for dissertations. We contacted tuberculosis experts for ongoing and unpublished studies. A WHO public call for data was made between 30 November 2023 and 15 February 2024.

SELECTION CRITERIA

We included cross-sectional and cohort studies that evaluated Truenat assays in sputum samples from adolescents and adults (aged 10 years and older). The microbiological reference standard for identifying pulmonary tuberculosis is culture. The reference standard for rifampicin resistance is a culture-based drug susceptibility test. Two review authors independently screened titles and abstracts, and assessed the full texts of potentially eligible articles. A third review author resolved any disagreements.

DATA COLLECTION AND ANALYSIS

We tailored and applied the QUADAS-2 and QUADAS-C tools to assess the risk of bias and applicability. Two review authors independently extracted data for each included study, and a third review author resolved any disagreements. We performed meta-analyses to estimate summary sensitivities and specificities using a bivariate model. We assessed the certainty of evidence using the GRADEpro GDT tool.

MAIN RESULTS

Of nine eligible articles, one contributed two distinct participant cohorts, which we considered as separate studies. Thus, we included 10 studies; three assessed Xpert Ultra. Most studies were set in low- and middle-income countries with a high tuberculosis burden. Six studies (4081 participants, 1379 with tuberculosis) assessed Truenat MTB, and four studies (3073 participants, 750 with tuberculosis) assessed Truenat MTB Plus. Two studies (966 participants, 111 with rifampicin resistance) assessed Truenat MTB-RIF Dx. Overall, the risk of bias in the included studies was low. Three of the 10 studies were judged to have high applicability concern in the patient selection domain. Detection of pulmonary tuberculosis The summary sensitivity of Truenat MTB was 87.6% (95% confidence interval (CI) 81.6 to 91.8; high-certainty evidence), and the summary specificity was 86.1% (95% CI 70.1 to 94.3; moderate-certainty evidence). For Truenat MTB Plus, the summary sensitivity was 90.6% (95% CI 83.7 to 94.8; high-certainty evidence), and the summary specificity was 95.7% (95% CI 94.7 to 96.5; high-certainty evidence). Based on the three comparative studies, the summary sensitivity of Truenat MTB was lower (81.0%, 95% CI 72.8 to 87.2) than that of Xpert Ultra (93.7%, 95% CI 90.4 to 95.9), while the summary specificity of Truenat MTB (97.0%, 95% CI 91.9 to 98.9) was marginally higher than Xpert Ultra (95.3%, 95% CI 90.9 to 97.7). Detection of rifampicin resistance The sensitivities from the two studies were 53% and 85% (moderate-certainty evidence) and specificities were both 97% (high-certainty evidence).

AUTHORS' CONCLUSIONS

Truenat MTB Plus had higher sensitivity and specificity than Truenat MTB. The high false-positive rate for Truenat MTB is a concern. The sensitivity of Xpert Ultra was significantly higher than that of Truenat MTB, while specificity was slightly lower. Evidence on the accuracy of Truenat MTB-RIF Dx was limited.

Consolidated Microscale Interferon-γ Release Assay with Tip Optofluidic Immunoassay for Dynamic Parallel Diagnosis of Tuberculosis Infection

Interferon-γ release assay (IGRA) is one of the most important diagnostic tools for tuberculosis (TB) infection. Despite its high accuracy, conventional IGRA has several drawbacks, including complicated procedures, large blood volume requirements, lengthy incubation times, and difficulties in parallel testing. Efforts have been made to develop miniaturized and highly sensitive biosensors for interferon-γ or to evaluate the specific immune response through microfluidic platforms. However, the need for sophisticated consumables and equipment, as well as the partial experimental design, has limited the application of these advanced techniques in TB diagnosis and disease control. Here, we report the development of a tip optofluidic immunoassay (TOI)-based consolidated microscale IGRA (CM-IGRA) for the dynamic and parallel evaluation of TB infection, refining both the blood incubation and interferon-γ quantification processes. The TOI system comprises 12 microfluidic immuno-reactors and a portable chemiluminescent imaging station, capable of quantifying interferon-γ with high sensitivity (8.00 pg/mL in plasma) and a wide detection range (∼104). The results generated with CM-IGRA achieved 98.39% agreement with the standard IGRA while reducing blood sample consumption to 50 μL per assay (20-fold reduction) and significantly shortening the incubation time from 20 to 10 h. This diagnostic method simplifies operations and improves efficiency for the parallel assays required in IGRA, providing a promising solution for TB screening in patients for whom current methods are inconvenient, such as children and older adults.

An Injectable Hydrogel Bioimplant Loaded with Engineered Exosomes and Triple Anti-Tuberculosis Drugs with Potential for Treating Bone and Joint Tuberculosis

Purpose

Treatment for bone and joint tuberculosis (BJTB) is challenging due to its refractory and recurrent nature. This study aimed to develop a bioimplantable scaffold with osteoinductive and antituberculosis characteristics to treat BJTB.

Methods

This scaffold is built on oxidized hyaluronic acid and carboxymethyl chitosan hydrogel mixed with hydroxyapatite as a bone tissue engineered material. In order to make the scaffold have the biological activity of promoting tissue repair, the engineered exosomes (Exoeng) were added innovatively. In addition, drug-loaded liposomes equipped with an aldehyde group on the surface are cross-linked with the amine group of the hydrogel skeleton to participate in the Schiff base reaction.

Results

The designed scaffold has characteristics of self-healing and injectability exhibit excellent anti-tuberculosis and promoting bone repair activities. Exoeng strongly stimulates cellular angiogenesis and osteogenic differentiation. The liposomes coated in hydrogel can release three kinds of anti-tuberculosis drugs smoothly and slowly, achieving a long term anti-tuberculosis.

Conclusion

The composite bio-scaffold shows good tissue repair and long-term anti-tuberculosis abilities, which expected to provide a viable treatment plan for bone-related BJTB.

Feasibility and staff acceptability of implementing Xpert HIV-1 viral load point-of-care testing: a pilot study in San Francisco

BACKGROUND

Point-of-care HIV viral load testing may enhance patient care and improve HIV health services. We aimed to evaluate the feasibility and acceptability of implementing such testing in a high-volume community sexual health clinic in the United States.

METHODS

We conducted a cross-sectional, mixed-methods study. Remnant venipuncture specimens from clients undergoing HIV and other sexual health screenings were analyzed using the Xpert® HIV-1 Viral Load assay. Results were compared to COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Test. Clinical staff observations, study meeting notes, and two semi-structured in-depth interviews with clinical staff were used to understand perspectives on incorporating this testing into clinical practice.

RESULTS

We analyzed 113 samples from 111 clients. The Xpert assay showed excellent agreement with COBAS, with no clinically significant difference in viral load measurements. Clinical staff found Xpert testing acceptable, based on its ability to provide rapid, accurate test results and potential for bridging patient care gaps. Respondents noted that this testing would be particularly beneficial for individuals in whom barriers to care engagement may complicate follow-up. Challenges in implementation included machine errors as well as concerns related to staff workload, testing logistics, and the need for comprehensive equipment training.

CONCLUSIONS

This study represents the first effort in the United States to describe the feasibility of HIV viral load point-of-care testing in routine care. While the Xpert demonstrated comparable results to standard-of-care testing and staff found it acceptable, further work is needed to develop the workflow and implementation strategies that would enable real-time use and improved patient care.

CLINICAL TRIAL

Not applicable.

Stool processing methods for Xpert Ultra testing in childhood tuberculosis: A prospective, multi-country accuracy study

Background

Centrifuge-free processing methods support stool Xpert Ultra testing for childhood tuberculosis (TB), but there are limited data on their accuracy, acceptability and usability.

Methods

We conducted a prospective evaluation of stool Xpert Ultra in India, South Africa, and Uganda with three methods: Stool Processing Kit (SPK), Simple One-Step (SOS), and Optimized Sucrose Flotation (OSF). Children <15 years old with presumptive TB had respiratory specimen testing with Xpert Ultra and culture. Stool was tested using Xpert Ultra after processing with each method. We compared the accuracy of each method to a microbiological reference standard (MRS) and a composite reference standard (CRS). We surveyed the laboratory staff to assess acceptability and usability of the methods.

Results

We included 607 children, of whom the median age was 3.5 years (IQR 1.3-7), 48% were female, and 15.5% were HIV positive. Against the MRS, the sensitivities of SPK, SOS and OSF were 36.9% (95% CI 28.6-45.8), 38.6% (95% CI 17.2-51), and 31.3% (95% CI 20.2-44.1), respectively. The specificities of SPK, SOS and OSF were 98.2% (95% CI 96.4-99.3), 97.3% (95% CI 93.7-99.1) and 97.1% (95% CI 93.3-99), respectively. Laboratory staff reported that the methods were acceptable and usable, but SOS was most feasible to implement in a peripheral facility. Sensitivity increased among children who were culture-positive (55-77.3%) and was low (13-16.7%) against the CRS.

Conclusions

Stool processing methods for Xpert Ultra were acceptable, usable, and performed similarly, with highest sensitivity among children with culture-positive TB.

Safety and yield of sputum induction for diagnosis of pulmonary tuberculosis in children in a tertiary hospital in Ghana

Background

Induced sputum (IS) is a sampling technique for obtaining lower airway samples for microbial investigations, including GeneXpert and culture for microbiological confirmation of Mycobacterium tuberculosis.

Objectives

To investigate the safety and yield of IS in children admitted to a tertiary hospital in Ghana with presumed pulmonary tuberculosis (PTB).

Methods

A prospective cross-sectional study was carried out in children aged 3 months - 14 years at Komfo Anokye Teaching Hospital in Kumasi, Ghana, over the 6-month period January - June 2022. All children with breathing difficulty and other signs of respiratory distress were given respiratory support, and IS samples were obtained when respiratory distress had resolved. One or two IS samples were collected from each child within 48 hours of admission by a trained nurse after at least 4 hours of fasting. Children were monitored during and for 30 minutes after the procedure, with recording of respiratory rate, oxygen saturation, temperature and pulse rate. They were also monitored for any adverse events such as vomiting, wheezing and nosebleeds.

Results

A total of 144 children were sampled, with approximately two-thirds sampled a second time. Nearly half of the participants were aged <2 years (49.3%; n=71/144), and the median (interquartile range (IQR)) age was 2.5 (0.9 - 6.8) years. Ninety-eight children (68.1%) tested positive for PTB by Xpert Ultra, with 19/98 (19.4%) being rifampicin resistant; 47/102 (46.1%) were positive by Ziehl-Neelsen staining, and 57/102 (55.9%) were positive by Auramine O staining. Three children (2.1%) had an episode of epistaxis following the procedure. No other adverse events were observed. Measurements before and 30 minutes to 1 hour after the procedure (median (IQR)) were similar: temperature 36.5°C (36.5 - 37.5°C) v. 36.5°C (36.2 - 37.1°C), oxygen saturation 98% (92 - 99%) v. 98% (93 - 99%), pulse rate 120 (106 - 139) v. 125 (112 - 142) bpm, and respiratory rate 38 (30 - 48) v. 33 (30 - 45) cycles per minute.

Conclusion

We found sputum induction to be a safe and well-tolerated procedure in the paediatric population, with minimal clinical risk and a high microbiological yield for PTB.

Study synopsis

What the study adds. This study is the first to provide information on the performance and safety of induced sputum (IS) in Ghanaian children. It shows that IS can be performed safely in this population, despite safety concerns that resulted in its late introduction in the country. In addition, it shows that IS procedures can provide quality sputum samples to improve bacteriological confirmation of pulmonary tuberculosis (PTB) in children with presumed tuberculosis. Lastly, it adds to the existing body of literature showing that with requisite training, sputum induction can be performed in low-income settings.Implications of the findings. The study shows that the IS procedure can be used in Ghana to help shift from traditional ways of obtaining sputum samples in children, such as gastric lavage and routine methods of obtaining sputum in older children without induction, to improve bacteriological confirmation when PTB is suspected. The findings indicate that roll-out to other health facilities in Ghana is possible.

Integrating Genomic Data with the Development of CRISPR-Based Point-of-Care-Testing for Bacterial Infections

Purpose of Review

Bacterial infections and antibiotic resistance contribute to global mortality. Despite many infections being preventable and treatable, the lack of reliable and accessible diagnostic tools exacerbates these issues. CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-based diagnostics has emerged as a promising solution. However, the development of CRISPR diagnostics has often occurred in isolation, with limited integration of genomic data to guide target selection. In this review, we explore the synergy between bacterial genomics and CRISPR-based point-of-care tests (POCT), highlighting how genomic insights can inform target selection and enhance diagnostic accuracy.

Recent Findings

We review recent advances in CRISPR-based technologies, focusing on the critical role of target sequence selection in improving the sensitivity of CRISPR-based diagnostics. Additionally, we examine the implementation of these technologies in resource-limited settings across Asia and Africa, presenting successful case studies that demonstrate their potential.

Summary

The integration of bacterial genomics with CRISPR technology offers significant promise for the development of effective point-of-care diagnostics.

Evaluation of targeted sequencing for pathogen identification in bone and joint infections: a cohort study from China

PURPOSE

Bone and joint tuberculosis (BJTB) is a distinct variant of tuberculosis in which clinical diagnosis often leads to relative misdiagnosis and missed diagnoses. This study aimed to evaluate the diagnostic accuracy of the targeted nanopore sequencing (TNPseq) assay for BJTB patients in China.

METHOD

The study enrolled a cohort of 163 patients with suspected BJTB. Diagnostic testing was performed using the TNPseq assay on samples including punctured tissue, pus, and blood. The diagnostic accuracy of the TNPseq assay was then compared with that of the T-SPOT and Xpert MTB/RIF assays.

RESULT

TNPseq exhibited superior performance in terms of accuracy, demonstrating a sensitivity of 76.3% (95% CI: 71.0-81.6%) and a specificity of 98.8% (95% CI: 93.5-100%) in clinical diagnosis. When evaluated against a composite reference standard, TNPseq demonstrated a sensitivity of 74.4% (95% CI: 69.3-79.5%) and a specificity of 98.8% (95% CI: 93.7-100%). These results exceed the performance of both the T-SPOT and Xpert MTB/RIF tests. Notably, TNPseq demonstrated high specificity and accuracy in puncture specimens, with a sensitivity of 75.0% (95% CI: 70.2-79.8%) and a specificity of 98.3% (95% CI: 92.7-100%), as well as in pus samples, with a sensitivity of 83.3% (95% CI: 78.6-88.1%) and a specificity of 100% (95% CI: 100-100%). Additionally, TNPseq facilitated the detection of mixed infection scenarios, identifying 20 cases of bacterial-fungal co-infection, 17 cases of bacterial-viral co-infection, and two cases of simultaneous bacterial-fungal-viral co-infection.

CONCLUSION

TNPseq demonstrated great potential in the diagnosis of BJTB due to its high sensitivity and specificity. The ability of TNPseq to diagnose pathogens and detect drug resistance genes can also guide subsequent treatment. Expanding the application scenarios and scope of TNPseq will enable it to benefit more clinical treatments.

Multidrug-resistant tuberculosis in children: A practical update on epidemiology, diagnosis, treatment and prevention

Pediatric multidrug-resistant tuberculosis (MDR-TB) remains a significant global problem, and there are numerous barriers preventing children with MDR-TB from being identified, confirmed with microbiologic tests, and treated with a safe, practical, and effective regimen. However, several recent advances in diagnostics and treatment regimens have the promise to improve outcomes for children with MDR-TB. We introduce this review with two cases that exemplify both the challenges in management of MDR-TB in children, but also the potential to achieve a positive outcome. More than 30,000 cases of MDR-TB per year are believed to occur in children but less than 5% are confirmed microbiologically, contributing to poorer outcomes and excess mortality. Rapid molecular-based testing that provides information on rifampin susceptibility is increasingly globally available and recommended for all children suspected of TB disease--but remains limited by challenges obtaining appropriate samples and the paucibacillary nature of most pediatric TB. More complex assays allowing better characterization of drug-resistant isolates are emerging. For children diagnosed with MDR-TB, treatment regimens have traditionally been long and utilize multiple drugs associated with significant side effects, particularly injectable agents. Several new or repurposed drugs including bedaquiline, delamanid, clofazimine and linezolid now allow most treatment regimens to be shorter and all-oral. Yet data to support short, all-oral, novel regimens for young children containing pretomanid remain insufficient at present, and there is a compelling need to conduct pediatric trials of promising therapeutics and MDR-TB treatment regimens.

Parallel use of low-complexity automated nucleic acid amplification tests on respiratory samples and stool with or without lateral flow lipoarabinomannan assays to detect pulmonary tuberculosis disease in children

OBJECTIVES

This is a protocol for a Cochrane Review (diagnostic). The objectives are as follows: To compare the diagnostic accuracy of the parallel use of low-complexity automated nucleic acid amplification tests on respiratory and stool specimens in children and lateral flow urine lipoarabinomannan amongst children with HIV versus each assay alone for detecting pulmonary tuberculosis. Secondary objectives To compare the diagnostic accuracy of low-complexity automated nucleic acid amplification tests on respiratory and stool specimens in combination versus each sample type alone. To investigate the following sources of heterogeneity: clinical setting, signs and symptoms of pulmonary tuberculosis disease, screening positivity by chest X-ray abnormalities, age group, specimen type; and also amongst children with HIV: CD4 cell-count or percent category, advanced HIV disease, and serious illness.

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.

Advancements in Tuberculosis Diagnostics: A Comprehensive Review of the Critical Role and Future Prospects of Xpert MTB/RIF Ultra Technology

Tuberculosis remains a persistent global health challenge, demanding swift and accurate diagnostic methods for effective treatment. The emergence of the Xpert MTB/RIF Ultra system marks a significant milestone in combating tuberculosis, streamlining the identification of Mycobacterium tuberculosis, and advancing our pursuit of eradicating the disease. Delving into the therapeutic landscape of tuberculosis and rifampicin resistance, this scientific narrative review offers a comprehensive exploration. It begins by delving into the historical backdrop and the hurdles encountered with traditional tuberculosis diagnostics. From there, it traces the journey of the Xpert MTB/RIF technology, underscoring its molecular underpinnings. In this narrative review, the performance of the Xpert MTB/RIF Ultra system undergoes thorough scrutiny, encompassing investigations into sensitivity, specificity, and comparisons with alternative diagnostic methods. The spotlight shines on its clinical applications across diverse scenarios, from diagnosing pulmonary and extrapulmonary tuberculosis to its pivotal role in identifying rifampicin resistance. The study also evaluates its clinical efficacy in enhancing patient outcomes and supporting global tuberculosis control initiatives. However, the review does not shy away from discussing the challenges and limitations associated with the Xpert MTB/RIF Ultra system. It meticulously addresses concerns regarding cost, infrastructure requirements, and potential diagnostic inaccuracies. Offering a panoramic view, the review assesses the system's impact in resource-constrained settings and its potential to bolster tuberculosis elimination endeavors worldwide. Peering into the future, it explores ongoing research avenues and potential enhancements in Xpert MTB/RIF Ultra technology, envisioning a landscape of improved performance, broader applications, and emerging diagnostic innovations in the realm of tuberculosis diagnostics.

Does multiple gastric aspirate collection increase sensitivity of M. tuberculosis detection in children with pulmonary tuberculosis?

This study aims to investigate the sensitivity of microscopy, culture and polymerase chain reaction on three gastric aspirates (GAs) in the microbiological confirmation of active pulmonary tuberculosis (TB) and to identify possible changes in sensitivity derived from the collection of a different number of aspirates. Children with clinical and radiological diagnoses of active pulmonary TB who underwent three GAs between March 2007 and June 2019 were retrospectively evaluated. Clinical, radiological, and microbiological data were collected. The sensitivity of microbiological tests on GAs was calculated. Moreover, differences in sensitivity according to age and radiological pattern were investigated. Overall, 156 children with active pulmonary TB were enrolled with a median age of 51.5 (IQR: 25.2-113.2) months. Microbiological investigations on the first GA showed a sensitivity of 34% (95%CI 26.7, 42), the cumulative sensitivity of first and second GAs was 40.4% (95%CI 32.7, 48.5) and of the three GAs was 47.4% (95%CI 39.8, 55.2). The collection of three GAs leads to an overall increase in sensitivity of the first GA by 13.4% (95%CI 2.8, 24.1%; p=0.014). Moreover, the increase in sensitivity was significantly higher in children ≤ 4 years of age and in those with uncomplicated TB (p=0.008).Conclusions: Performing a higher number of GAs increases the sensitivity of microbiological confirmation of active pulmonary TB, particularly in children ≤ 4 years and with an uncomplicated radiological pattern. What is known: • The diagnosis of paediatric tuberculosis is a challenge for paediatricians • Despite their low sensitivity gastric aspirates represent the standard sample for microbiological confirmation of active pulmonary tuberculosis in children • Most international guidelines recommend performing three sequential gastric aspirates on three consecutive days What is new: • A significant increase in global sensitivity by 13.4% was found by the collection of three gastric aspirates compared to the first one • Performing a higher number of gastric aspirates increases the sensitivity of microbiological confirmation, particularly in children ≤ 4 years and with an uncomplicated radiological pattern.

The diagnostic yield of nasopharyngeal aspirate for pediatric pulmonary tuberculosis: a systematic review and meta-analysis

Background

Tuberculosis (TB) is a leading cause of death in children, but many cases are never diagnosed. Microbiological diagnosis of pulmonary TB is challenging in young children who cannot spontaneously expectorate sputum. Nasopharyngeal aspirates (NPA) may be more easily collected than gastric aspirate and induced sputum and can be obtained on demand, unlike stool. However, further information on its diagnostic yield is needed.

Methods

We systematically reviewed and meta-analyzed the diagnostic yield of one NPA for testing by either culture or nucleic acid amplification testing (NAAT) to detect Mycobacterium tuberculosis from children. We searched three bibliographic databases and two trial registers up to 24th November 2022. Studies that reported the proportion of children diagnosed by NPA compared to a microbiological reference standard (MRS) were eligible. Culture and/or WHO-endorsed NAAT on at least one respiratory specimen served as the MRS. We also estimated the incremental yield of two NPA samples compared to one and summarized operational aspects of NPA collection and processing. Univariate random-effect meta-analyses were performed to calculate pooled diagnostic yield estimates.

Results

From 1483 citations, 54 were selected for full-text review, and nine were included. Based on six studies including 256 children with microbiologically confirmed TB, the diagnostic yield of NAAT on one NPA ranged from 31 to 60% (summary estimate 44%, 95% CI 36-51%). From seven studies including 242 children with confirmed TB, the diagnostic yield of culture was 17-88% (summary estimate 58%, 95% CI 42-73%). Testing a second NPA increased the yield by 8-19% for NAAT and 4-35% for culture. NPA collection procedures varied between studies, although most children had NPA successfully obtained (96-100%), with a low rate of indeterminate results (< 5%). Data on NPA acceptability and specifically for children under 5 years were limited.

Conclusions

NPA is a suitable and feasible specimen for diagnosing pediatric TB. The high rates of successful collection across different levels of healthcare improve access to microbiological testing, supporting its inclusion in diagnostic algorithms for TB, especially if sampling is repeated. Future research into the acceptability of NPA and how to standardize collection to optimize diagnostic yield is needed.

Recent advances in microbiological and molecular biological detection techniques of tuberculous meningitis

Tuberculous meningitis (TBM) is the most common type of central nervous system tuberculosis (TB) and has the highest mortality and disability rate. Early diagnosis is key to improving the prognosis and survival rate of patients. However, laboratory diagnosis of TBM is often difficult due to its paucibacillary nature and sub optimal sensitivity of conventional microbiology and molecular tools which often fails to detect the pathogen. The gold standard for TBM diagnosis is the presence of MTB in the CSF. The recognised methods for the identification of MTB are acid-fast bacilli (AFB) detected under CSF smear microscopy, MTB cultured in CSF, and MTB detected by polymerase chain reaction (PCR). Currently, many studies consider that all diagnostic techniques for TBM are not perfect, and no single technique is considered simple, fast, cheap, and efficient. A definite diagnosis of TBM is still difficult in current clinical practice. In this review, we summarise the current state of microbiological and molecular biological diagnostics for TBM, the latest advances in research, and discuss the advantages of these techniques, as well as the issues and challenges faced in terms of diagnostic effectiveness, laboratory infrastructure, testing costs, and clinical expertise, for clinicians to select appropriate testing methods.

Development and preliminary assessment of a CRISPR-Cas12a-based multiplex detection of Mycobacterium tuberculosis complex

Since the onset of the COVID-19 pandemic in 2020, global efforts towards tuberculosis (TB) control have encountered unprecedented challenges. There is an urgent demand for efficient and cost-effective diagnostic technologies for TB. Recent advancements in CRISPR-Cas technologies have improved our capacity to detect pathogens. The present study established a CRISPR-Cas12a-based multiplex detection (designated as MCMD) that simultaneously targets two conserved insertion sequences (IS6110 and IS1081) to detect Mycobacterium tuberculosis complex (MTBC). The MCMD integrated a graphene oxide-assisted multiplex recombinase polymerase amplification (RPA) assay with a Cas12a-based trans-cleavage assay identified with fluorescent or lateral flow biosensor (LFB). The process can be performed at a constant temperature of around 37°C and completed within 1 h. The limit of detection (LoD) was 4 copies μL-1, and no cross-reaction was observed with non-MTBC bacteria strains. This MCMD showed 74.8% sensitivity and 100% specificity in clinical samples from 107 patients with pulmonary TB and 40 non-TB patients compared to Xpert MTB/RIF assay (63.6%, 100%). In this study, we have developed a straightforward, rapid, highly sensitive, specific, and cost-effective assay for the multiplex detection of MTBC. Our assay showed superior diagnostic performance when compared to the widely used Xpert assay. The novel approach employed in this study makes a substantial contribution to the detection of strains with low or no copies of IS6110 and facilitates point-of-care (POC) testing for MTBC in resource-limited countries.

Trends and challenges of multi-drug resistance in childhood tuberculosis

Drug-resistant tuberculosis (DR-TB) in children is a growing global health concern, This review provides an overview of the current epidemiology of childhood TB and DR-TB, including prevalence, incidence, and mortality. We discuss the challenges in diagnosing TB and DR-TB in children and the limitations of current diagnostic tools. We summarize the challenges associated with treating multi-drug resistance TB in childhood, including limitations of current treatment options, drug adverse effects, prolonged regimens, and managing and monitoring during treatment. We highlight the urgent need for improved diagnosis and treatment of DR-TB in children. The treatment of children with multidrug-resistant tuberculosis will be expanded to include the evaluation of new drugs or new combinations of drugs. Basic research is needed to support the technological development of biomarkers to assess the phase of therapy, as well as the urgent need for improved diagnostic and treatment options.

Multidrug-Resistant TB (MDR-TB) and Extensively Drug-Resistant TB (XDR-TB) Among Children: Where We Stand Now

Drug-resistant tuberculosis (DR-TB) has continued to be a global health cataclysm. It is an arduous condition to tackle but is curable with the proper choice of drug and adherence to the drug therapy. WHO has introduced newer drugs with all-oral shorter regimens, but the COVID-19 pandemic has disrupted the achievements and raised the severity. The COVID-19 controlling mechanism is based on social distancing, using face masks, personal protective equipment, medical glove, head shoe cover, face shield, goggles, hand hygiene, and many more. Around the globe, national and international health authorities impose lockdown and movement control orders to ensure social distancing and prevent transmission of COVID-19 infection. Therefore, WHO proposed a TB control program impaired during a pandemic. Children, the most vulnerable group, suffer more from the drug-resistant form and act as the storehouse of future fatal cases. It has dire effects on physical health and hampers their mental health and academic career. Treatment of drug-resistant cases has more success stories in children than adults, but enrollment for treatment has been persistently low in this age group. Despite that, drug-resistant childhood tuberculosis has been neglected, and proper surveillance has not yet been achieved. Insufficient reporting, lack of appropriate screening tools for children, less accessibility to the treatment facility, inadequate awareness, and reduced funding for TB have worsened the situation. All these have resulted in jeopardizing our dream to terminate this deadly condition. So, it is high time to focus on this issue to achieve our Sustainable Development Goals (SDGs), the goal of ending TB by 2030, as planned by WHO. This review explores childhood TB's current position and areas to improve. This review utilized electronic-based data searched through PubMed, Google Scholar, Google Search Engine, Science Direct, and Embase.

Truenat MTB assays for pulmonary tuberculosis and rifampicin resistance in adults

This is a protocol for a Cochrane Review (diagnostic). The objectives are as follows:

To determine the diagnostic accuracy of Truenat assays (MTB, MTB Plus, and MTB RIF Dx) for detecting pulmonary tuberculosis and rifampicin resistance in adults with presumptive pulmonary tuberculosis.