Diagnosis of paediatric tuberculosis using sputum induction in Botswana: programme description and findings

Rapid tuberculosis diagnosis from respiratory or blood samples by a low cost, portable lab-in-tube assay

Rapid portable assays are needed to improve diagnosis, treatment, and reduce transmission of tuberculosis (TB), but current tests are not suitable for patients in resource-limited settings with high TB burden. Here we report a low complexity, lab-in-tube system that is read by an integrated handheld device that detects Mycobacterium tuberculosis (Mtb) DNA in blood and respiratory samples from a variety of clinical settings. This microprocessor-controlled device uses an LCD user interface to control assay performance, automate assay analysis, and provide results in a simple readout. This point-of-care single-tube assay uses a DNA enrichment membrane and a low-cost cellulose disc containing lyophilized recombinase polymerase amplification and CRISPR-Cas12a reagents to attain single-nucleotide specificity and high sensitivity within 1 hour of sample application, without a conventional DNA isolation procedure. Assay results obtained with serum cell-free DNA isolated from a cohort of children aged 1 to 16 years detected pulmonary and extrapulmonary TB with high sensitivity versus culture and GeneXpert MTB/RIF results (81% versus 55% and 68%) and good specificity (94%), meeting the World Health Organization target product profile criteria for new nonsputum TB diagnostics. Changes in assay results for serum isolated during treatment were also highly predictive of clinical response. Results obtained with noninvasive sputum and saliva specimens from adults with bacteriologically confirmed pulmonary TB were also comparable to those reported for reference methods. This rapid and inexpensive lab-in-tube assay approach thus represents one means to address the need for point-of-care TB diagnostics useable in low-resource settings.

Unlocking the potential of miRNAs in detecting pulmonary tuberculosis: prospects and pitfalls

Tuberculosis (TB) is one of the deadliest infectious diseases globally, ranking as 13th leading cause of mortality and morbidity. According to the Global Tuberculosis Report 2022, TB claimed the lives of 1.6 million people worldwide in 2021. Among the casualties, 1 870 000 individuals with HIV co-infections contributed to 6.7% of the total fatalities, accounting TB as the second most lethal infectious disease following COVID-19. In the quest to identify biomarkers for disease progression and anti-TB therapy, microRNAs (miRNAs) have gained attention due to their precise regulatory role in gene expression in disease stages and their ability to distinguish latent and active TB, enabling the development of early TB prognostic signatures. miRNAs are stable in biological fluids and therefore will be useful for non-invasive and broad sample collection. However, their inherent lack of specificity and experimental variations may lead to false-positive outcomes. These limitations can be overcome by integrating standard protocols with machine learning, presenting a novel tool for TB diagnostics and therapeutics. This review summarizes, discusses and highlights the potential of miRNAs as a biomarker, particularly their differential expression at disease stages. The review assesses the advantages and obstacles associated with miRNA-based diagnostic biomarkers in pulmonary TB and facilitates rapid, point-of-care testing.

Comparative analysis of pediatric pulmonary and extrapulmonary tuberculosis: A single-center retrospective cohort study in Syria

Background

Tuberculosis (TB) is a global public health challenge, contributing significantly to morbidity and mortality worldwide. This research aims to investigate the epidemiology, clinical characteristics, diagnostic methods, and early mortality rate among pediatric patients with pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB) who were admitted to a hospital in Syria.

Methods

This retrospective cohort study was conducted at the University Children's Hospital in Syria, involving pediatric patients diagnosed with TB between January 2013 and January 2023. Data were collected from medical records and encompassed socio-demographic characteristics, diagnostic methods, clinical presentation, chest radiography findings, and patient outcomes. Statistical analysis was performed using SPSS version 25.

Results

A total of 129 patients were included in the study, with 26.4 % diagnosed with PTB and 73.6 % with EPTB. The most common types of EPTB were lymphatic (25.6 %) and gastrointestinal (17.1 %). Patients with PTB and EPTB did not differ significantly in terms of age, weight, or gender. Significant cough was more common in PTB cases (67.6 %), while lymphadenopathy was more prevalent in EPTB cases (48.4 %). Chest X-ray abnormalities were found in 58.1 % of patients, with PTB patients more likely to have abnormal findings (97.1 %). Microbiological confirmation was higher in PTB cases (76.5 %) compared to EPTB cases (25.3 %). The overall mortality rate was 14 %, with higher mortality observed in patients with EPTB (16.8 %), particularly in cases of TB meningitis.

Conclusion

Our study highlights the epidemiological challenges of TB among hospitalized children, with a focus on the complexities of diagnosing and managing EPTB. We emphasize the urgent need for enhanced diagnostic and management strategies, particularly in conflict zones like Syria, where TB control efforts face significant obstacles. Prompt solutions are imperative to improve outcomes, given the high occurrence of EPTB and its associated mortality rates. Clinical recommendations stress the need for comprehensive contact histories and awareness of varied clinical presentations in pediatric TB diagnosis.

Exploring cytokine dynamics in tuberculosis: A comparative analysis of patients and controls with insights from three-week antituberculosis intervention

Despite developing new diagnostics, drugs, and vaccines, treating tuberculosis (TB) remains challenging. Monitoring inflammatory markers can contribute to more precise diagnostics of TB, identifying its active and latent forms, or monitoring its treatment success. We assessed alterations in plasma levels of 48 cytokines in 20 patients (17 males) with active pulmonary TB compared to age-matched healthy controls (n = 18). Blood samples were collected from individuals hospitalised with TB prior to commencing antibiotic therapy, after the first week, and following the third week. The majority of patients received treatment with a combination of four first-line antituberculosis drugs: rifampicin, isoniazid, ethambutol, and pyrazinamide. Plasmatic cytokine levels from patients three times and controls were analyzed using a Bio-Plex Pro Human Cytokine Screening Panel. The results showed significantly higher levels of 31 cytokines (p<0.05) than healthy controls. Three-week therapy duration showed significantly decreased levels of nine cytokines: interferon alpha-2 (IFN-α2), interleukin (IL) 1 alpha (IL-1α), IL-1 receptor antagonist (IL-1ra), IL-6, IL-10, IL-12 p40, IL-17, leukemia inhibitory factor (LIF), and tumor necrosis factor alpha (TNF-α). Out of these, only levels of IL-1α and IL-6 remained significantly elevated compared to controls. Moreover, we have found a negative correlation of 18 cytokine levels with BMI of the patients but no correlation with age. Our results showed a clinical potential for monitoring the levels of specific inflammatory markers after a short treatment duration. The reduction in cytokine levels throughout the course of therapy could indicate treatment success but should be confirmed in studies with more individuals involved and a longer observation period.

Pediatric tuberculosis outcomes and factors associated with unfavorable treatment outcomes in Botswana, 2008-2019: a retrospective analysis

INTRODUCTION

Globally, the amount of research on the outcomes of pediatric tuberculosis (TB) is disproportionately less than that of adult TB. The diagnosis of paediatric TB is also problematic in developing countries. The aim of this study was to describe the outcomes of pediatric TB in Botswana and to identify the factors associated with unfavorable outcomes.

METHODS

This was a retrospective analysis of pediatric TB outcomes in Botswana, over a 12-year period from January 2008 to December 2019. Treatment success (treatment completion or cured) was considered a favorable outcome, while death, loss to follow-up and treatment failure were considered unfavorable outcomes. Program data from drug-sensitive TB (DS-TB) cases under the age of 15 years were included. Sampling was exhaustive. Binary logistic regression was used to determine the factors associated with unfavorable outcomes during TB treatment. A p value of < 0.05 was considered a statistically significant association between the predictor variables and unfavorable outcomes.

RESULTS

The data of 6,004 paediatric TB cases were extracted from the Botswana National TB Program (BNTP) electronic registry and analyzed. Of these data, 2,948 (49.4%) were of female patients. Of the extracted data, 1,366 (22.8%) were of HIV positive patients and 2,966 (49.4%) were of HIV negative patients. The rest of the data were of patients with unknown HIV status. Pulmonary TB accounted for 4,701 (78.3%) of the cases. Overall, 5,591 (93.1%) of the paediatric TB patient data showed treatment success, 179 (3.0%) were lost to follow-up, 203 (3.4%) records were of patients who died, and 31 (0.5%) were of patients who experienced treatment failure. The factors associated with unfavorable outcomes were positive HIV status (AOR 2.71, 95% CI: 2.09-3.52), unknown HIV status (AOR 2.07, 95% CI: 1.60-2.69) and retreatment category (AOR 1.92, 95% CI: 1.30-2.85). Compared with the 0-4 years age category, the 5-9 years (AOR 0.62, 95% CI: 0.47-0.82) and 10-14 years (AOR 0.76, 95% CI: 0.60-0.98) age categories were less likely to experience the unfavorable outcomes.

CONCLUSION

This study shows a high treatment success rate among paediatric TB cases in Botswana. The government under the National TB Program should maintain and consolidate the gains from this program. Public health interventions should particularly target children with a positive or unknown HIV status, those under 5 years, and those who have been previously treated for TB.

Oral Swab Specimens Tested With Xpert MTB/RIF Ultra Assay for Diagnosis of Pulmonary Tuberculosis in Children: A Diagnostic Accuracy Study

BACKGROUND

Microbiologic diagnosis of childhood tuberculosis may be difficult. Oral swab specimens are a potential noninvasive alternative to sputum specimens for diagnosis.

METHODS

This was a prospective diagnostic accuracy study of oral swab specimens (buccal and tongue) for pulmonary tuberculosis diagnosis in children (aged ≤ 15 years) in 2 South African hospital sites. Children with cough of any duration as well as a positive tuberculin skin test result, tuberculosis contact, loss of weight, or chest radiograph suggestive of pulmonary tuberculosis were enrolled. Two induced sputum specimens were tested with Xpert MTB/RIF (or Xpert MTB/RIF Ultra) assay and liquid culture. Oral swab specimens were obtained before sputum specimens, frozen, and later tested with Xpert MTB/RIF Ultra. Children were classified as microbiologically confirmed tuberculosis, unconfirmed tuberculosis (receipt of tuberculosis treatment), or unlikely tuberculosis according to National Institutes of Health consensus definitions based on sputum microbiologic results.

RESULTS

Among 291 participants (median age [interquartile range], 32 [14-73] months), 57 (20%) had human immunodeficiency virus (HIV), and 87 (30%) were malnourished; 90 (31%) had confirmed pulmonary tuberculosis (rifampicin resistant in 6 [7%] ), 157 (54%), unconfirmed pulmonary tuberculosis, and 44 (15%), unlikely tuberculosis. A single oral swab specimen was obtained from 126 (43%) of the participants (tongue in 96 and buccal in 30) and 2 swab specimens from 165 (57%) (tongue in 110 and buccal in 55). Sensitivity was low (22% [95% confidence interval, 15%-32%]) for all swab specimens combined (with confirmed pulmonary tuberculosis as reference), but specificity was high (100% [91%-100%]). The highest sensitivity was 33% (95% confidence interval, 15%-58%) among participants with HIV. The overall yield was 6.9% with 1 oral swab specimen and 7.2% with 2.

CONCLUSIONS

Use of the Xpert MTB/RIF Ultra assay with oral swab specimens provides poor yield for microbiologic pulmonary tuberculosis confirmation in children.

The utility of a modified WHO TB screening tool among children at a Botswana child welfare clinic

Background

In high TB/HIV settings, the increased risk for TB amongst children exposed to HIV has been established through biomedical tests. Screening HIV exposed children for TB can improve early childhood TB detection and treatment.

Objective

This study assessed the utility of a modified World Health Organization (WHO) tool by including HIV variables, to determine TB exposure amongst HIV exposed children presenting to a “Well Child” Clinic (CWC).

Methods

Clinical data were obtained from medical records and/or from the caregivers of children presenting to CWC. Data was analyzed to explore factors associated with positive screening for TB, including being exposed to HIV and current HIV status.

Results

Five percent (55/1100) screened reported a close TB contact and 21% (n=231) had positive TB symptom screen. History of close TB contact was a risk factor for positive screening for TB symptoms (OR 1.89 CI 1.05–3.4) while being HIV negative was protective (OR 0.3, Cl 0.19–0.62). HIV exposure was associated with increased risk of TB exposure (OR 2.9 CI 1.61–5.19).

Conclusion

Integrating HIV variables in the existing WHO screening tool for childhood TB can be useful in early detection and treatment of TB in HIV exposed children in resource limited settings.

Lipoarabinomannan antigenic epitope differences in tuberculosis disease subtypes

An accurate urine test for diverse populations with active tuberculosis could be transformative for preventing TB deaths. Urinary liporabinomannan (LAM) testing has been previously restricted to HIV co-infected TB patients. In this study we evaluate urinary LAM in HIV negative, pediatric and adult, pulmonary and extrapulmonary tuberculosis patients. We measured 430 microbiologically confirmed pretreatment tuberculosis patients and controls from Peru, Guinea Bissau, Venezuela, Uganda and the United States using three monoclonal antibodies, MoAb1, CS35, and A194, which recognize distinct LAM epitopes, a one-sided immunoassay, and blinded cohorts. We evaluated sources of assay variability and comorbidities (HIV and diabetes). All antibodies successfully discriminated TB positive from TB negative patients. ROAUC from the average of three antibodies’ responses was 0.90; 95% CI 0.87–0.93, 90% sensitivity, 73.5% specificity (80 pg/mL). MoAb1, recognizing the 5-methylthio-d-xylofuranose(MTX)-mannose(Man) cap epitope, performed the best, was less influenced by glycosuria and identified culture positive pediatric (N = 19) and extrapulmonary (N = 24) patients with high accuracy (ROAUC 0.87, 95% CI 0.77–0.98, 0.90 sensitivity 0.80 specificity at 80 pg/mL; ROAUC = 0.96, 95% CI 0.92–0.99, 96% sensitivity, 80% specificity at 82 pg/mL, respectively). The MoAb1 antibody, recognizing the MTX-Man cap epitope, is a novel analyte for active TB detection in pediatric and extrapulmonary disease.

Alternative sputum collection methods for diagnosis of childhood intrathoracic tuberculosis: a systematic literature review

BACKGROUND

Diagnosis of intrathoracic tuberculosis (ITB) is limited in children partly by their difficulty to produce sputum specimen.

OBJECTIVE

To systematically review the detection yields of mycobacterial culture and Xpert MTB/RIF from induced sputum (IS), nasopharyngeal aspirate (NPA) and gastric aspirate (GA) in children with presumptive ITB.

DESIGN

Pubmed, Embase and Biosis databases and grey literature were searched. Randomised controlled trials, cohort, cross-sectional or case control studies using IS, GA and NPA for diagnosis of ITB published between January 1990 and January 2018 were included. Data were extracted on study design, case definition of presumptive ITB, sample collection methods, outcome measures and results.

RESULTS

30 studies were selected, including 11 554 children. Detection yields for culture ranged between 1% and 30% for IS, 1% and 45% for GA and 4% and 24% for NPA. For Xpert MTB/RIF, it was between 2% and 17% for IS, 5% and 51% for GA and 3% and 8% for NPA. There was a tendency of better yields with IS when the pretest probability of ITB was low to moderate and with GA when it was high. Sampling a second specimen contributed for 6%-33% of the cumulative yield and combination of different methods significantly increase the detection yields.

CONCLUSIONS

Despite the important study heterogeneity, any of the specimen collection methods offers good potential to confirm childhood ITB. However, their operational challenges were poorly evaluated. In the absence of a sensitive non-sputum based test, only a minority of children with ITB can be confirmed.

Safety of Induced Sputum Collection in Children Hospitalized With Severe or Very Severe Pneumonia

Background.

Induced sputum (IS) may provide diagnostic information about the etiology of pneumonia. The safety of this procedure across a heterogeneous population with severe pneumonia in low- and middle-income countries has not been described.

Methods.

IS specimens were obtained as part a 7-country study of the etiology of severe and very severe pneumonia in hospitalized children <5 years of age. Rigorous clinical monitoring was done before, during, and after the procedure to record oxygen requirement, oxygen saturation, respiratory rate, consciousness level, and other evidence of clinical deterioration. Criteria for IS contraindications were predefined and serious adverse events (SAEs) were reported to ethics committees and a central safety monitor.

Results.

A total of 4653 IS procedures were done among 3802 children. Thirteen SAEs were reported in relation to collection of IS, or 0.34% of children with at least 1 IS specimen collected (95% confidence interval, 0.15%–0.53%). A drop in oxygen saturation that required supplemental oxygen was the most common SAE. One child died after feeding was reinitiated 2 hours after undergoing sputum induction; this death was categorized as “possibly related” to the procedure.

Conclusions.

The overall frequency of SAEs was very low, and the nature of most SAEs was manageable, demonstrating a low-risk safety profile for IS collection even among severely ill children in low-income-country settings. Healthcare providers should monitor oxygen saturation and requirements during and after IS collection, and assess patients prior to reinitiating feeding after the IS procedure, to ensure patient safety.

Evaluation of a Urine-Based Rapid Molecular Diagnostic Test with Potential to Be Used at Point-of-Care for Pulmonary Tuberculosis: Cape Town Cohort

Tuberculosis (TB) diagnosis among sputum-scarce patients is time consuming. Thus, a nonsputum diagnostic alternative is urgently needed. The Mycobacterium tuberculosis-specific transrenal (Tr) DNA from urine is a potential target for TB diagnostics. In this study, a new urine-based Tr-DNA molecular assay was evaluated for diagnosis of pulmonary tuberculosis among 428 adults suspected of having pulmonary TB (164 HIV positive, 263 HIV negative) from Cape Town, South Africa. Tr-DNA was isolated from 4 mL of EDTA urine, and a rapid, double-stranded, primer-based PCR method was performed targeting the Mycobacterium tuberculosis-specific direct repeat region. Each Tr-DNA eluate was tested in triplicate using an automated molecular analyzer with controls included in each test. With liquid culture used as the gold standard, the Tr-DNA assay showed sensitivity of 42.9% (n = 75/175; 95% CI, 35.4%-50.5%) and specificity of 88.6% (n = 210/237; 95% CI, 83.9%-92.4%). Among HIV-infected patients with TB, sensitivity and specificity were 45.2% and 89.0%, respectively. The combination of smear microscopy and Tr-DNA increased the sensitivity to 83.8% (smear microscopy alone, 75.1%), with 96.6% specificity. This study indicates that Tr-DNA has a moderate specificity with low sensitivity for diagnosis of pulmonary TB. Despite low sensitivity, this diagnostic test may have potential in combination with smear microscopy to support TB diagnosis in HIV-endemic regions, where sputum-scarce patients are common.