Diagnosis of pulmonary tuberculosis in children: new advances

Accuracy of Xpert and alternative sampling methods to diagnose childhood pulmonary tuberculosis, a prospective cohort study

OBJECTIVES

To estimate the sensitivity and specificity of childhood pulmonary tuberculosis (CPTB) diagnostic tests, including Xpert MTB/RIF and alternative samples such as nasopharyngeal aspirate and stool. We used latent class analysis to overcome the lack of reference standards.

METHODS

We included 1165 children suspected of having CPTB in a prospective cohort study conducted in the Ivory Coast, Madagascar, and Cameroon. We used Bayesian latent class analysis to evaluate the performance of multiple diagnostic tests for CPTB: smear microscopy, mycobacterial culture, and Xpert carried out on different types of samples (sputum after 10 years of age, gastric aspirate before 10 years of age, nasopharyngeal aspirate, and stool), tuberculin skin test, and chest X-ray.

RESULTS

Median age was 3.5 years (95% credible interval [1.3-8.2]). Smear microscopy was highly specific in all types of samples but lacked sensitivity (sputum 31%; 95% credible interval [18-46]), gastric aspirate 36% [27-45], nasopharyngeal aspirate 24% [17-32], and stool 24% [17-32]). Culture sensitivity was slightly higher in gastric (75% [65-83]) than in nasopharyngeal aspirate (64% [54-72]). Xpert sensitivity was similar in gastric (69% [59-78]) and nasopharyngeal aspirate (66% [57-74]) but lower in sputum (58% [43-74]) and stools (53% [44-62]). Xpert was highly specific in all respiratory samples (sputum 96% [96-100], gastric aspirate 100% [99-100], and nasopharyngeal aspirate 100% [99-100]).

DISCUSSION

The Xpert performed on the nasopharyngeal aspirate shows similar accuracy to the culture. It was also similar to that in gastric aspirate. It highlights an interesting CPTB diagnostic combination.

Cell-Mediated Immune Response Against Mycobacterium tuberculosis and Its Potential Therapeutic Impact

Cell-mediated immune response is critical for Mycobacterium tuberculosis (M.tb) control. Understanding of pathophysiology and role played by different cell mediators is essential for vaccine development and better management of patients with M.tb. A complex array of cytokines and chemokines are involved in the immune response against M.tb; however, their relative contribution in protection remains to be further explored. The purpose of this review is to summarize the current understanding regarding the cytokine and chemokine profiles in M.tb infection in order to assist research in the field to pursue new direction in prevention and control. We have also summarized recent findings on vaccine trials that have been developed and or are under trials that are targeting these molecules.

A comparison of chest radiographic findings in human immunodeficiency virus-positive and -negative children with pulmonary tuberculosis

AIM

To compare chest radiography (CXR) findings in human immunodeficiency virus (HIV)-positive and HIV-negative children who had microbiologically confirmed pulmonary tuberculosis (PTB).

MATERIALS AND METHODS

Retrospective analysis of CXRs from children with known HIV status and microbiologically confirmed PTB (culture or GeneXpert Xpert MTB/RIF positive), who were hospitalised or seen at a primary healthcare centre over a 5-year period. Radiological findings were compared according to HIV and nutritional status.

RESULTS

CXRs of 130 children were analysed from 35 (27%) HIV- positive and 95 (73%) HIV-negative children with confirmed PTB, median age 45.7 months (interquartile range [IQR] 18-81.3 months). CXR changes consistent with PTB were reported in 21/35 (60%) of HIV-positive and 59/95 (62%) of HIV-negative patients, (p=0.81). Normal CXR was identified in 3/35 (8.6%) of HIV-positive and 5/95 (5.3%) of HIV-negative patients (p=0.81). Airway compression was present in 3/35 (8.6%) of HIV-positive and 7/95 (7.4%) of HIV-negative patients (p>0.99). Overall, lymphadenopathy was identified in 42/130 (32.3%) of patients, 11/35 (31.4 %) were HIV-positive compared with 31/95 (32.6%) HIV-negative patients. Airspace consolidation was present in 60% of both HIV-positive (21/35) and HIV-negative patients (57/95). Pleural effusion was present in 2/35 (5.7 %) of HIV-negative and 9/95 (9.5 %) of HIV-negative patients. There were no statistically significant radiological differences by HIV group.

CONCLUSION

There were no significant differences in the CXR findings between the HIV-positive and HIV-negative children with confirmed PTB.

Diagnostic Accuracy of Clinical Diagnostic Scoring Systems for Childhood Tuberculosis: A Systematic Review and Meta-analysis

Background

Diagnosis of childhood tuberculosis (TB) poses several challenges. Therefore, point-based scoring systems and diagnostic algorithms have been developed to improve the diagnostic yields in this population. However, there are no updated systematic reviews of the existing childhood TB scoring systems and algorithms. Hence, we systematically reviewed the diagnostic accuracy of the childhood TB diagnostic scoring systems and algorithms.

Methods

We systematically searched PubMed, CINAHL, Embase, Scopus, and Google Scholar databases for relevant articles published until 30 March 2023. QUADAS-2 was used to assess their study quality. Diagnostic accuracy measures (ie, sensitivity, specificity, diagnostic odds ratio, positive and negative likelihood ratios) were pooled using a random-effects model.

Results

We included 15 eligible studies, with a total of 7327 study participants aged <15 years, with 10 evaluations of childhood TB diagnostic scoring systems and algorithms. Among these algorithms and scoring systems, only 3 were evaluated more than once. These were the Keith Edwards scoring system with 5 studies (sensitivity, 81.9%; specificity, 81.2%), Kenneth Jones criteria with 3 studies (sensitivity, 80.1%; specificity, 45.7%), and the Ministry of Health-Brazil algorithm with 3 studies (sensitivity, 79.9%; specificity, 73.2%).

Conclusions

We recommend using the Keith Edwards scoring system because of its high sensitivity and specificity. Further research is necessary to assess the effectiveness of scoring systems and algorithms in identifying TB in children with HIV and malnutrition.

Pulmonary Tuberculosis and Rifampicin Resistant Mycobacterium Tuberculosis in Children and Adolescents using Gene Xpert MTB/RIF Assay in Tigray, Northern Ethiopia

Background

Tuberculosis (TB) continues to be a global health problem. While childhood TB contributes 10% to the global TB burden, the paucibacillary nature of TB disease in children and the absence of reliable diagnostic methods have made MTB diagnosis in children to be a great challenge. This study aimed to determine the prevalence of MTB and rifampicin-resistant MTB (RR-MTB) among children using Gene Xpert MTB/RIF Assay in Tigray, Ethiopia.

Methods

A retrospective database study was conducted among children in ten governmental hospitals in the Tigray region. Gene Xpert MTB/RIF results of sputum/gastric lavage samples from children with presumptive TB from January 2016 to December 2019 were extracted using a data extraction sheet. Data were collected and analyzed using Statistical Package for the Social Sciences version 21.

Results

The prevalence of bacteriologically confirmed MTB by Gene-Xpert in children with presumptive TB was 7.3% (95% CI: 6.7%-7.9%) and the proportion of those that were Gene-Xpert MTB positive who also have rifampicin resistance was 10.9% (95% CI: 8.2-13.6%). Older children aged 11-15 years [AOR = 1.76; 95% CI = 1.33-2.33, p < 0.001] and adolescents 16-17 years [AOR = 2.18; 95% CI = 1.63-2.92, p < 0.001] were more likely to be MTB positive. Relapse cases [AOR = 1.66; 95% CI = 1.09-2.51, p = 0.017] and lost/failure cases [AOR = 8.82; 95% CI = 3.94-19.76, p < 0.001] were more likely to have MTB compared to the new cases.

Conclusion

The proportion of MTB-positive among the TB presumptive patients was 7.3%. The proportion of rifampicin-resistant TB to all positive patients was 10.9%. Female participants had more MTB than males (or younger children). The result highlights the need for due attention in children because it is very helpful in determining the future control of the disease.

Systematic review of diagnostic and prognostic host blood transcriptomic signatures of tuberculosis disease in people living with HIV

Background HIV-associated tuberculosis (TB) has high mortality; however, current triage and prognostic tools offer poor sensitivity and specificity, respectively. We conducted a systematic review of diagnostic and prognostic host-blood transcriptomic signatures of TB in people living with HIV (PLHIV). Methods We systematically searched online databases for studies published in English between 1990-2020. Eligible studies included PLHIV of any age in test or validation cohorts, and used microbiological or composite reference standards for TB diagnosis. Inclusion was not restricted by setting or participant age. Study selection, quality appraisal using the QUADAS-2 tool, and data extraction were conducted independently by two reviewers. Thereafter, narrative synthesis of included studies, and comparison of signatures performance, was performed. Results We screened 1,580 records and included 12 studies evaluating 31 host-blood transcriptomic signatures in 10 test or validation cohorts of PLHIV that differentiated individuals with TB from those with HIV alone, latent Mycobacterium tuberculosis infection, or other diseases (OD). Two (2/10; 20%) cohorts were prospective (29 TB cases; 51 OD) and 8 (80%) case-control (353 TB cases; 606 controls) design. All cohorts (10/10) were recruited in Sub-Saharan Africa and 9/10 (90%) had a high risk of bias. Ten signatures (10/31; 32%) met minimum WHO Target Product Profile (TPP) criteria for TB triage tests. Only one study (1/12; 8%) evaluated prognostic performance of a transcriptomic signature for progression to TB in PLHIV, which did not meet the minimum WHO prognostic TPP. Conclusions Generalisability of reported findings is limited by few studies enrolling PLHIV, limited geographical diversity, and predominantly case-control design, which also introduces spectrum bias. New prospective cohort studies are needed that include PLHIV and are conducted in diverse settings. Further research exploring the effect of HIV clinical, virological, and immunological factors on diagnostic performance is necessary for development and implementation of TB transcriptomic signatures in PLHIV.

Systematic review of diagnostic and prognostic host blood transcriptomic signatures of tuberculosis disease in people living with HIV

Background HIV-associated tuberculosis (TB) has high mortality; however, current triage and prognostic tools offer poor sensitivity and specificity, respectively. We conducted a systematic review of diagnostic and prognostic host-blood transcriptomic signatures of TB in people living with HIV (PLHIV). Methods We systematically searched online databases for studies published in English between 1990-2020. Eligible studies included PLHIV of any age in test or validation cohorts, and used microbiological or composite reference standards for TB diagnosis. Inclusion was not restricted by setting or participant age. Study selection, quality appraisal using the QUADAS-2 tool, and data extraction were conducted independently by two reviewers. Thereafter, narrative synthesis of included studies, and comparison of signatures performance, was performed. Results We screened 1,580 records and included 12 studies evaluating 31 host-blood transcriptomic signatures in 10 test or validation cohorts of PLHIV that differentiated individuals with TB from those with HIV alone, latent Mycobacterium tuberculosis infection, or other diseases (OD). Two (2/10; 20%) cohorts were prospective (29 TB cases; 51 OD) and 8 (80%) case-control (353 TB cases; 606 controls) design. All cohorts (10/10) were recruited in Sub-Saharan Africa and 9/10 (90%) had a high risk of bias. Ten signatures (10/31; 32%) met minimum WHO Target Product Profile (TPP) criteria for TB triage tests. Only one study (1/12; 8%) evaluated prognostic performance of a transcriptomic signature for progression to TB in PLHIV, which did not meet the minimum WHO prognostic TPP. Conclusions Generalisability of reported findings is limited by few studies enrolling PLHIV, limited geographical diversity, and predominantly case-control design, which also introduces spectrum bias. New prospective cohort studies are needed that include PLHIV and are conducted in diverse settings. Further research exploring the effect of HIV clinical, virological, and immunological factors on diagnostic performance is necessary for development and implementation of TB transcriptomic signatures in PLHIV.

Feasibility of novel approaches to detect viable Mycobacterium tuberculosis within the spectrum of the tuberculosis disease

Tuberculosis (TB) is a global disease caused by Mycobacterium tuberculosis (Mtb) and is manifested as a continuum spectrum of infectious states. Both, the most common and clinically asymptomatic latent tuberculosis infection (LTBI), and the symptomatic disease, active tuberculosis (TB), are at opposite ends of the spectrum. Such binary classification is insufficient to describe the existing clinical heterogeneity, which includes incipient and subclinical TB. The absence of clinically TB-related symptoms and the extremely low bacterial burden are features shared by LTBI, incipient and subclinical TB states. In addition, diagnosis relies on cytokine release after antigenic T cell stimulation, yet several studies have shown that a high proportion of individuals with immunoreactivity never developed disease, suggesting that they were no longer infected. LTBI is estimated to affect to approximately one fourth of the human population and, according to WHO data, reactivation of LTBI is the main responsible of TB cases in developed countries. Assuming the drawbacks associated to the current diagnostic tests at this part of the disease spectrum, properly assessing individuals at real risk of developing TB is a major need. Further, it would help to efficiently design preventive treatment. This quest would be achievable if information about bacterial viability during human silent Mtb infection could be determined. Here, we have evaluated the feasibility of new approaches to detect viable bacilli across the full spectrum of TB disease. We focused on methods that specifically can measure host-independent parameters relying on the viability of Mtb either by its direct or indirect detection.

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.

The Magnitude of MTB and Rifampicin Resistance MTB Using Xpert-MTB/RIF Assay Among Tuberculosis Suspected Patients in Gedeo Zone, Southern Ethiopia

Background

Tuberculosis (TB) remains a major global health problem causing death among millions of people each year. The new barrier that challenges the control of tuberculosis is the emerging and the increasing number of drug-resistant TB that becomes a world concern. This study aimed to determine the magnitude of rifampicin-resistant Mycobacterium tuberculosis (RR-MTB) among presumptive TB patients attending Dilla University Referral Hospital, Gedeo Zone, Ethiopia.

Methods

A retrospective cross-sectional study was conducted at Dilla University Referral Hospital from January 2014 to December 2020. Sputum results were done using Xpert MTB/RIF assay and other necessary data were collected from the registration logbooks using a standardized data extraction format and analyzed using SPSS version 23 statistical software.

Results

A total of 17,745 presumptive TB patients were included, of which 62.2% were males. The overall prevalence of Mycobacterium tuberculosis (MTB) was 11.8%, of which 5.1% were confirmed to have RR-MTB. Extra-pulmonary TB was reported in 1.5% of the study participants. The highest prevalence of MTB and RR-MTB was recorded in 2017 with a prevalence of 20.1% and 8.5%, respectively. All age groups were significantly associated with a higher prevalence of MTB (p < 0.036). TB patients with a history of previous treatment and HIV positive were significantly associated with MTB (P < 0.021), while RR-MTB was only significantly associated with patients with a history of previous treatment (P < 0.018).

Conclusion

A high magnitude of MTB and RR-MTB was reported among TB patients with HIV and a history of previous treatment. Therefore, coordinated efforts should be applied to the improvement of treatment adherence of known TB cases, and appropriate control and prevention methods to reduce the emergence and increase of MTB and RR-MTB cases.

Retrospective cohort analysis of survival of children living with HIV/AIDS in Mumbai, India

OBJECTIVES

To understand the survival in a cohort of children living with HIV/AIDS (CLHAs) and to study the factors associated with survival in CLHAs in government antiretroviral therapy (ART) centres in Mumbai, India.

DESIGN

This is a retrospective cohort analysis.

SETTING

Data from electronic ART records of children from 15 ART centres in Mumbai, Maharashtra, India.

PARTICIPANTS

2224 CLHAs registered in one of these ART centres from 2004 until October 2019. CLHAs up to the age of 18 at the time of registration were considered for these analyses.

PRIMARY AND SECONDARY OUTCOMES

We accessed the following data: date of test, date of initiation of ART, date of last follow-up, age at the time of registration, gender, potential route of infection, baseline CD4 counts, ART regimen, adherence and presence of co-infection (TB). We estimated the survival probabilities, plotted the Kaplan-Meier survival graphs and estimated HRs for mortality.

RESULTS

The mortality rate in our population was 22.75 (95% CI 20.02 to 25.85) per 1000 person-years. The 1-year survival was 0.92 (95% CI 0.91 to 0.93), 0.89 (95% CI 0.88 to 0.91) at 5 years and 0.85 (95% CI 0.83 to 0.87) at 10 years after initiation of ART. Children with adherence less than 80% had lowest survival in the first year (0.54, 95% CI 0.46 to 0.61). It reduced drastically at 5 and 10 years. After adjusting for demographic and clinical parameters, mortality was associated with poor adherence (<80%) (HR 11.70, 95% CI 8.82 to 15.53; p<0.001). However, CD4 counts of greater than 200 and age more than 1 year were protective.

CONCLUSIONS

Poor adherence to ART and low CD4 counts were significantly associated with higher mortality. Adherence counselling should be an important component of CLHA monitoring in all ART centres. It is also important to identify children early in the infection and start ART medications appropriately.

Comparison of performances of loop-mediated isothermal amplification, XPERT MTB/RIF and BACTEC MGIT in the diagnosis of childhood tuberculosis

AIM

Key to the successful management of paediatric pulmonary tuberculosis (PTB) lies in the early detection and proper treatment. We evaluated the performances of modern diagnostic tests: loop-mediated isothermal amplification (LAMP-IS6110), Xpert MTB/RIF (Cepheid) and mycobacteria growth indicator tube (BACTEC MGIT 960 culture) against a modified version of international consensus diagnostic definition (i.e. composite reference standard (CRS)).

METHODS

A cross-sectional analytical study was conducted in a tertiary care hospital in North India from July 2016 to December 2017 involving 100 children <14 years with suspected PTB. Respiratory specimens (sputum, gastric lavage and/or bronchoalveolar lavage) were collected and subjected to LAMP-IS6110, Xpert MTB/RIF and BACTEC MGIT 960 culture assay.

RESULTS

Fifty-five children had confirmed and probable TB according to the CRS (prevalence = 58.5%). The sensitivity of BACTEC MGIT 960 culture, Xpert MTB/RIF and LAMP-IS6110 assay was 14%, 9.1% and 10.91%, respectively, when compared against the predefined CRS. The specificity for all these tests was 100%. When compared with BACTEC MGIT 960 culture as the gold standard, the LAMP-IS6110 assay and Xpert MTB/RIF assay had the sensitivity of 85.71% (95% CI: 42.13-99.64%) and 71.43% (95% CI: 29.04-96.33%), respectively. The specificity of both assays was 100%.

CONCLUSIONS

We noted that LAMP-IS6110 performed better than Xpert MTB/RIF (Cepheid) in terms of sensitivity when compared against BACTEC MGIT 960 culture as reference standard, though specificity of both the tests was comparable. The diagnostic performance of BACTEC MGIT 960 culture was better than LAMP-IS6110 and Xpert MTB/RIF in paediatric PTB, when compared against CRS.

Evaluation of a serum-based antigen test for tuberculosis in HIV-exposed infants: a diagnostic accuracy study

BACKGROUND

Non-sputum methods are urgently needed to improve tuberculosis diagnosis and treatment monitoring in children. This study evaluated the ability of a serum assay quantifying a species-specific peptide of the Mycobacterium tuberculosis CFP-10 virulence factor via nanotechnology and matrix-assisted laser desorption ionization time-of-flight mass spectrometry to diagnose tuberculosis in HIV-infected and HIV-uninfected infants.

METHODS

Serum CFP-10 peptide signal was blinded evaluated in cryopreserved sera of 519 BCG-immunized, HIV-exposed infants (284 HIV-infected, 235 HIV-uninfected) from a multi-center randomized placebo-controlled isoniazid prophylaxis trial conducted in southern Africa between 2004 and 2008, who were followed up to 192 weeks for Mtb infection and TB. Children were classified as confirmed, unconfirmed, or unlikely tuberculosis cases using 2015 NIH diagnostic criteria for pediatric TB.

RESULTS

In HIV-infected infants, CFP-10 signal had 100% sensitivity for confirmed TB (5/5, 95% CI, 47.8-100) and 83.7% sensitivity for unconfirmed TB (36/43, 95% CI 69.3-93.2), with 93.1% specificity (203/218, 95% CI 88.9-96.1). In HIV-uninfected infants, CFP-10 signal detected the single confirmed TB case and 75.0% of unconfirmed TB cases (15/20; 95% CI 50.9-91.3), with 96.2% specificity (177/184, 95% CI, 92.3-98.5). Serum CFP-10 achieved 77% diagnostic sensitivity for confirmed and unconfirmed TB (13/17, 95% CI, 50-93%) at ≤ 24 weeks pre-diagnosis, and both CFP-10-positivity and concentration declined following anti-TB therapy initiation.

CONCLUSIONS

Serum CFP-10 signal exhibited high diagnostic sensitivity and specificity for tuberculosis in HIV-infected and HIV-uninfected infants and potential utility for early TB detection and monitoring of anti-TB treatment responses.

Comparing accuracy of lipoarabinomannan urine tests for diagnosis of pulmonary tuberculosis in children from four African countries: a cross-sectional study

BACKGROUND

A sensitive and specific non-sputum-based test would be groundbreaking for the diagnosis of childhood tuberculosis. We assessed side by side the diagnostic accuracy of the urine-based lipoarabinomannan assays Fujifilm SILVAMP TB LAM (FujiLAM) and Alere Determine TB LAM Ag (AlereLAM) for detection of childhood tuberculosis.

METHODS

In this cross-sectional study, we tested urine samples from children younger than 15 years with presumed pulmonary tuberculosis. Children were consecutively recruited from four dedicated outpatient childhood tuberculosis clinics in The Gambia, Mali, Nigeria, and Tanzania. Biobanked urine samples were thawed and tested using FujiLAM and AlereLAM assays. We measured diagnostic performance against a microbiological reference standard (confirmed tuberculosis) and a composite reference standard (confirmed and unconfirmed tuberculosis). Sensitivity and specificity were estimated with bivariate random-effects meta-analyses.

FINDINGS

Between July 1, 2017, and Dec 1, 2018, we obtained and stored urine samples from 415 children. 63 (15%) children had confirmed tuberculosis, 113 (27%) had unconfirmed tuberculosis, and 239 (58%) were unlikely to have tuberculosis. 61 children were HIV-positive (prevalence 15%). Using the microbiological reference standard, the sensitivity of FujiLAM was 64·9% (95% CI 43·7-85·2; positive in 40 of 63 confirmed samples) and the sensitivity of AlereLAM was 30·7% (8·6-61·6; 19 of 63). The specificity of FujiLAM was 83·8% (95% CI 76·5-89·4; negative in 297 of 352 unconfirmed and unlikely samples) and the specificity of AlereLAM was 87·8% (79·0-93·7; 312 of 352). Against the composite reference standard, both assays had decreased sensitivity; the sensitivity of FujiLAM was 32·9% (95% CI 24·6-41·9; positive in 58 of 176 confirmed and unconfirmed samples) and the sensitivity of AlereLAM was 20·2% (12·3-29·4; 36 of 176). The specificity of FujiLAM was 83·3% (95% CI 71·8-91·7; negative in 202 of 239 unlikely samples) and the specificity of AlereLAM was 90·0% (81·6-95·6; 216 of 239).

INTERPRETATION

By comparison with AlereLAM, FujiLAM showed higher sensitivity and similar specificity. FujiLAM could potentially add value to the rapid diagnosis of tuberculosis in children.

FUNDING

German Federal Ministry of Education and Research, the Global Health Innovative Technology Fund, the UK Research and Innovation Global Challenges Research Fund, and the UK Medical Research Council.

Screening of potential biomarkers for distinguishing between latent and active tuberculosis in children using bioinformatics analysis

Tuberculosis (TB) is one of the leading causes of childhood morbidity and death globally. Lack of rapid, effective non-sputum diagnosis and prediction methods for TB in children are some of the challenges currently faced. In recent years, blood transcriptional profiling has provided a fresh perspective on the diagnosis and predicting the progression of tuberculosis. Meanwhile, combined with bioinformatics analysis can help to identify the differentially expressed genes (DEGs) and functional pathways involved in the different clinical stages of TB. Therefore, this study investigated potential diagnostic markers for use in distinguishing between latent tuberculosis infection (LTBI) and active TB using children's blood transcriptome data.From the Gene Expression Omnibus database, we downloaded two gene expression profile datasets (GSE39939 and GSE39940) of whole blood-derived RNA sequencing samples, reflecting transcriptional signatures between latent and active tuberculosis in children. GEO2R tool was used to screen for DEGs in LTBI and active TB in children. Database for Annotation, Visualization and Integrated Discovery tools were used to perform Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis. STRING and Cytoscape analyzed the protein-protein interaction network and the top 15 hub genes respectively. Receiver operating characteristics curve was used to estimate the diagnostic value of the hub genes.A total of 265 DEGs were identified, including 79 upregulated and 186 downregulated DEGs. Further, 15 core genes were picked and enrichment analysis revealed that they were highly correlated with neutrophil activation and degranulation, neutrophil-mediated immunity and in defense response. Among them TLR2, FPR2, MMP9, MPO, CEACAM8, ELANE, FCGR1A, SELP, ARG1, GNG10, HP, LCN2, LTF, ADCY3 had significant discriminatory power between LTBI and active TB, with area under the curves of 0.84, 0.84, 0.84, 0.80, 0.87, 0.78, 0.88, 0.84, 0.86, 0.82, 0.85, 0.85, 0.79, and 0.88 respectively.Our research provided several genes with high potential to be candidate gene markers for developing non-sputum diagnostic tools for childhood Tuberculosis.

Childhood Intra-Thoracic Tuberculosis Clinical Presentation Determines Yield of Laboratory Diagnostic Assays

Diagnosis of intra-thoracic tuberculosis (ITTB) in children is difficult due to the paucibacillary nature of the disease, the challenge in collecting appropriate specimens, and the low sensitivity of smear microscopy and culture. Culture and Xpert MTB/RIF provide higher diagnostic yield in presumptive TB in adults than in children. Current study was designed to understand poor yield of diagnostic assays in children. Children with presumptive ITTB were subjected to gastric aspirates and induced sputum twice. Samples were tested by Ziehl-Neelsen stain, Xpert MTB/RIF-assay, and MGIT-960 culture. Subjects were grouped as Confirmed, Unconfirmed, and Unlikely TB, and classified as progressive primary disease (PPD, lung parenchymal lesion), and primary pulmonary complex (PPC, hilar lymphadenopathy) on chest X-ray. Of children with culture-positive TB 51/394 (12.9%), culture-negative TB 305 (77.4%), and unlikely TB 38 (9.6%), 9 (2.3%) were smear positive, while 95 (24.1%) were Xpert-MTB/RIF positive. Xpert-MTB/RIF detected 40/51 culture confirmed cases (sensitivity 78.4% and NPV 96.3%). Culture was positive in more children presenting as PPD (p < 0.04). In culture-negative TB group, Xpert positivity was seen in 31% of those with PPD and 11.9% in those with PPC (p < 0.001). Conclusion: Xpert-MTB/RIF improved diagnosis by 2-fold and increased detection of MDR-TB. Both liquid culture and Xpert-MTB/RIF gave higher yield in children with lung parenchymal lesions. Children with hilar lymphadenopathy without active lung parenchymal lesions had poor diagnostic yield even with sensitive nucleic acid amplification tests, due to paucibacillary/localized disease, suggesting possible utility of invasively collected samples in early diagnosis and treatment.

Integration of metabolomics and transcriptomics reveals novel biomarkers in the blood for tuberculosis diagnosis in children

Pediatric tuberculosis (TB) remains a major global health problem. Improved pediatric diagnostics using readily available biosources are urgently needed. We used liquid chromatography-mass spectrometry to analyze plasma metabolite profiles of Indian children with active TB (n = 16) and age- and sex-matched, Mycobacterium tuberculosis-exposed but uninfected household contacts (n = 32). Metabolomic data were integrated with whole blood transcriptomic data for each participant at diagnosis and throughout treatment for drug-susceptible TB. A decision tree algorithm identified 3 metabolites that correctly identified TB status at distinct times during treatment. N-acetylneuraminate achieved an area under the receiver operating characteristic curve (AUC) of 0.66 at diagnosis. Quinolinate achieved an AUC of 0.77 after 1 month of treatment, and pyridoxate achieved an AUC of 0.87 after successful treatment completion. A set of 4 metabolites (gamma-glutamylalanine, gamma-glutamylglycine, glutamine, and pyridoxate) identified treatment response with an AUC of 0.86. Pathway enrichment analyses of these metabolites and corresponding transcriptional data correlated N-acetylneuraminate with immunoregulatory interactions between lymphoid and non-lymphoid cells, and correlated pyridoxate with p53-regulated metabolic genes and mitochondrial translation. Our findings shed new light on metabolic dysregulation in children with TB and pave the way for new diagnostic and treatment response markers in pediatric TB.

Frequency of MTB and rifampicin resistance MTB using Xpert-MTB/RIF assay among adult presumptive tuberculosis patients in Tigray, Northern Ethiopia: A cross sectional study

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) continues to be a global health problem. Data on rifampicin resistance MTB using Xpert- MTB/RIF assay in Ethiopia, particularly in the study area is limited. The aim of this study was to determine the frequency of MTB and rifampicin resistant-MTB among presumptive tuberculosis patients in Tigray, Northern Ethiopia.

METHODS

A multicenter retrospective study was conducted among presumptive TB patients from five governmental hospitals and one comprehensive specialized teaching hospital in Tigray regional state. Records of sputum sample results of presumptive MTB patients with Xpert-MTB/RIF assay from January 2016 to December 2019 were investigated. Data extraction tool was used to collect data from registration books and analyzed using SPSS ver.21 statistical software. Statistical significance was set at p-value ≤ 0.05.

RESULTS

Of the 30,935 presumptive adult TB patients who have provided specimens for TB diagnosis from January 2016 to December 2019, 30,300 (98%) had complete data and were included in this study. More than half, 17,471 (57.7%) were males, and the age of the patients ranged from 18-112 years, with a median age of 40.65 (interquartile 29.4-56.5 years). Majority, 28,996 (95.7%) of the participants were treatment naïve, and 23,965 (79.1%) were with unknown HIV status. The overall frequency of MTB was 2,387 (7.9% (95% CI: 7.6-8.2%); of these, 215 (9% (95% CI: 7.9-10.2%) were rifampicin resistant-MTB. Age (18-29 years), HIV positive and previous TB treatment history were significantly associated with high MTB (p < 0.001), whereas gender (being female) was associated with low MTB (p < 0.001). Likewise, rifampicin resistant-MTB was more prevalent among relapse (p < 0.001) and failure cases (p = 0.025); while age group 30-39 years was significantly associated with lower frequency of rifampicin resistant-MTB (p = 0.008).

CONCLUSION

Frequency of MTB among tuberculosis presumptive patients was low; however, the problem of rifampicin resistant-MTB among the tuberculosis confirmed patients was high. The high frequency of MTB and RR-MTB among previously treated and HIV positive patients highlights the need for more efforts in TB treatment and monitoring program in the study area.

Evaluation of stool GeneXpert MTB/RIF for the diagnosis of pulmonary tuberculosis among presumptive patients in Tanzania

Background

Diagnosis of pulmonary tuberculosis remains grim, especially in resource-limited settings. Low quality of sputum, particularly among seriously ill, HIV/AIDS, and pediatric patients might result in missing the diagnosis. This study evaluated the performance of GeneXpert MTB/RIF for the detection of pulmonary tuberculosis on stool specimens as an alternative to respiratory specimens.

Methods

A cross-sectional study design was used to evaluate the performance of GeneXpert MTB/RIF to detect TB in stool specimens from presumptive TB patients. Sputum culture on Lowenstein-Jensen media was used as the gold standard. Recruitment of patients into the study was conducted in 12 selected health facilities in Tanzania. Two sputa and a stool specimen were collected from each study participant. Both sputa and stool samples were tested at their respective study sites of collection using GeneXpert, and their respective portions shipped to the Central Tuberculosis Reference Laboratory for testing by stool GeneXpert and sputum culture in the LJ media. Statistical analysis was performed using STATA software version 14.1.

Results

A total of 590 presumptive tuberculosis patients were enrolled in this study. Their median age was 35 years (IQR = 21–47 years). More than half (57.5%, n = 339) of the study participants, were males. Children aged below 15 years constituted 17.6% (n = 104) of the study participants. A total of 75 tuberculosis cases were detected by sputum culture. The sensitivity and specificity of Stool GeneXpert conducted at CTRL was 84% (95% CI: 81.0–87.0%), and 93.4% (CI: 98.5–99.9%) respectively. The overall sensitivity and specificity of stool GeneXpert at the peripheral laboratories was 63.0% (95% CI: 47.8–76.1) and 76.7% (95% CI: 72.1–81.4), respectively.

Conclusion

Findings from this study suggest that stool is a potential alternative to respiratory specimen for use in routine diagnosis of tuberculosis, especially when obtaining a respiratory specimen is challenging.

Pediatric Tuberculosis: The Impact of "Omics" on Diagnostics Development

Tuberculosis (TB) is a major public health concern for all ages. However, the disease presents a larger challenge in pediatric populations, partially owing to the lack of reliable diagnostic standards for the early identification of infection. Currently, there are no biomarkers that have been clinically validated for use in pediatric TB diagnosis. Identification and validation of biomarkers could provide critical information on prognosis of disease, and response to treatment. In this review, we discuss how the “omics” approach has influenced biomarker discovery and the advancement of a next generation rapid point-of-care diagnostic for TB, with special emphasis on pediatric disease. Limitations of current published studies and the barriers to their implementation into the field will be thoroughly reviewed within this article in hopes of highlighting future avenues and needs for combating the problem of pediatric tuberculosis.

Paediatric tuberculosis diagnosis using Mycobacterium tuberculosis real-time polymerase chain reaction assay: protocol for systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) diagnosis in children is a major challenge with up to 94% of children with TB treated empirically in TB high-burden countries. Paediatric tuberculosis (PTB) remains a major cause of morbidity and mortality globally, particularly in developing countries. Most deaths/morbidity from TB in paediatrics could be prevented with early diagnosis and appropriate treatment. The main objective of this systematic review is to examine the evidence whether real-time polymerase chain reaction assay could be the most accurate clinical laboratory diagnostic methodology for the Mycobacterium tuberculosis (MTB) detection in paediatrics.

METHODS

We will search MEDLINE/PubMed, EMBASE, BIOSIS, LILACS, Cochrane Infectious Diseases Group Specialised Register (CIDG SR), Global Health, and CINAHL for published studies that recruited children less than 16 years of age being investigated for Mycobacterium tuberculosis (MTB) infection using real-time polymerase chain reaction assay accompanied by mycobacteriological culture investigation as the reference standard. There will be no restriction regarding the language, date of publication, and publication status. We will include randomised controlled trials and observational studies (cohort, cross-sectional) in the review. Selection of studies, data extraction and management, assessment of risk of bias, and quality of evidence will be performed by two independent reviewers (EB and BC). A third researcher will be consulted in case of discrepancies. Depending on the availability and quality of the data, a meta-analysis will be performed. Otherwise, findings will be qualitatively reported.

DISCUSSION

To our knowledge, this is the first systematic review and meta-analysis assessing the detection of MTB from all clinical sample types using real-time polymerase chain reaction assay in paediatric population. This review will make available evidence on the accuracy, approach, and interpretation of results of this assay in the context of MTB diagnosis which will meet an urgent need, considering the challenges of MTB diagnosis in paediatrics.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018104052.

Computed tomography-based predictive nomogram for differentiating primary progressive pulmonary tuberculosis from community-acquired pneumonia in children

Background

To investigate the value of predictive nomogram in optimizing computed tomography (CT)-based differential diagnosis of primary progressive pulmonary tuberculosis (TB) from community-acquired pneumonia (CAP) in children.

Methods

This retrospective study included 53 patients with clinically confirmed pulmonary TB and 62 patients with CAP. Patients were grouped at random according to a 3:1 ratio (primary cohort n = 86, validation cohort n = 29). A total of 970 radiomic features were extracted from CT images and key features were screened out to build radiomic signatures using the least absolute shrinkage and selection operator algorithm. A predictive nomogram was developed based on the signatures and clinical factors, and its performance was assessed by the receiver operating characteristic curve, calibration curve, and decision curve analysis.

Results

Initially, 5 and 6 key features were selected to establish a radiomic signature from the pulmonary consolidation region (RS1) and a signature from lymph node region (RS2), respectively. A predictive nomogram was built combining RS1, RS2, and a clinical factor (duration of fever). Its classification performance (AUC = 0.971, 95% confidence interval [CI]: 0.912–1) was better than the senior radiologist’s clinical judgment (AUC = 0.791, 95% CI: 0.636-0.946), the clinical factor (AUC = 0.832, 95% CI: 0.677–0.987), and the combination of RS1 and RS2 (AUC = 0.957, 95% CI: 0.889–1). The calibration curves indicated a good consistency of the nomogram. Decision curve analysis demonstrated that the nomogram was useful in clinical settings.

Conclusions

A CT-based predictive nomogram was proposed and could be conveniently used to differentiate pulmonary TB from CAP in children.

Electronic supplementary material

The online version of this article (10.1186/s12880-019-0355-z) contains supplementary material, which is available to authorized users.

IP-10 for the diagnosis of tuberculosis in children: Protocol for a systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) is a highly contagious and chronic disease. The microbiological examination to confirm children TB disease are limited due to paucibacillary Mycobacterium, specimens and detecting facilities. Considering these limitations in diagnosing children TB, new and reliable methods that detect children TB should be developed. Recently, Interferon gamma-induced protein 10 (IP-10) has been identified as a sensitive parameter in detecting children TB. The present study aims to synthesis and analysis the diagnostic value of IP-10 for children TB.

METHODS

We will search PubMed, Embase, the Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure, and Chinese Biological Medical Databases. We will search relevant citations up to May 2019. The quality of individual study will be assessed using the Quality Assessment of Diagnostic Accuracy Studies tool-2 (QUADAS-2). Stata 14.0 software will be used to calculate the pooled sensitivity, pooled specificity, pooled positive likelihood ratio (PLR), pooled negative likelihood ratio (NLR), pooled diagnostic odds ratio (DOR), pre-test probability, post-test probability and the hierarchical summary receiver operating characteristic (HSROC) curve.

RESULTS

The results of this study will be published in a peer-reviewed journal.

DISCUSSION

The evidence will indicate that IP-10 test is an alternative immunological test in detecting children TB. This is a protocol of systematic review and meta-analysis, so the ethical approval and patient consent are not required.

PROTOCOL REGISTRATION NUMBER

CRD42019129743.

Xpert MTB/RIF diagnosis of childhood tuberculosis from sputum and stool samples in a high TB-HIV-prevalent setting

The Xpert MTB/RIF assay is a major advance for diagnosis of tuberculosis (TB) in high-burden countries but is limited in children by their difficulty to produce sputum. We investigated TB in sputum and stool from children with the aim of improving paediatric TB diagnosis. A prospective cohort of children with presumptive TB, provided two sputum or induced sputum at enrolment in a regional referral hospital in Uganda. Stool was collected from those started on TB treatment. All specimen were tested for Xpert MTB/RIF, mycobacteria growth indicator tube (MGIT), Lowenstein Jensen cultures and microscopy (except stool). We compared TB detection between age categories and assessed the performance of Xpert MTB/RIF in sputum and stool. Of the 392 children enrolled, 357 (91.1%) produced at least one sputum sample. Sputum culture yield was 13/357 (3.6%): 3/109 (2.6%), 3/89 (3.2%), 3/101 (2.6%) and 4/44 (8.2%) among children of < 2, 2-5, ≥ 5-10 and > 10 years, respectively (p = 0.599). Xpert MTB/RIF yield was 14/350 (4.0%): 3/104 (2.9%), 4/92 (4.3%), 3/88 (2.9%) and 4/50 (.0%), respectively (p = 0.283). Sensitivity and specificity of Xpert MTB/RIF in sputum against sputum culture were 90.9% (95% CI 58.7-99.8) and 99.1% (99.1-99.8). In stool, it was 55.6% (21.2-86.3) and 98.2% (98.2-100) against Xpert MTB/RIF and culture in sputum. Only a minority of children had microbiologically confirmed TB with a higher proportion in children above 10 years. Although sensitivity of Xpert MTB/RIF in stool was low, with good optimization, it might be a good alternative to sputum in children.

Evaluation of Xpert MTB/RIF assay in children with presumed pulmonary tuberculosis in Papua New Guinea

BACKGROUND

The Gene Xpert MTB/ RIF assay (Xpert) is used for rapid, simultaneous detection of Mycobacterium tuberculosis (MTB) and rifampicin resistance. This study examined the accuracy of Xpert in children with suspected pulmonary tuberculosis (PTB).

METHODS

Children admitted to Port Moresby General Hospital with suspected PTB were prospectively enrolled between September 2014 and March 2015. They were classified into probable, possible and TB-unlikely groups. Sputum or gastric aspirates were tested by Xpert and smear microscopy; mycobacterial culture was undertaken on a subset. Children were diagnosed with TB on the basis of standard criteria which were used as the primary reference standard. Xpert, smear for acid-fast bacilli (AFB) and the Edwards TB score were compared with the primary reference standard.

RESULTS

A total of 93 children ≤14 years with suspected PTB were enrolled; 67 (72%) were classified as probable, 21 (22%) possible and 5 (5.4%) TB-unlikely. Eighty were treated for TB based on the primary reference standard. Xpert was positive in 26/93 (28%) MTB cases overall, including 22/67 (33%) with probable TB and 4/21 (19%) with possible TB. Three (13%) samples identified rifampicin resistance. Xpert confirmed more cases of TB than AFB smear (26 vs 13, p = 0.019). The sensitivity of Xpert, AFB smear and an Edwards TB score of ≥7 was 31% (25/80), 16% (13/80) and 90% (72/80), respectively, and the specificity was 92% (12/13), 100% (13/13) and 31% (4/13), respectively, when compared with the primary reference standard.

CONCLUSION

Xpert sensitivity is sub-optimal and cannot be relied upon for diagnosing TB, although a positive result is confirmatory. A detailed history and examination, standardised clinical criteria, radiographs and available tests remain the most appropriate way of diagnosing TB in children in resource-limited countries. Xpert helps confirm PTB better than AFB smear, and identifies rifampicin resistance. Practical guidelines should be used to identify children who will benefit from an Xpert assay.

Role of PCR method using IS6110 primer in detecting Mycobacterium tuberculosis among the clinically diagnosed childhood tuberculosis patients at an urban hospital in Dhaka, Bangladesh

OBJECTIVE

Better methods are needed for the accurate detection of child tuberculosis (TB). This study compared different laboratory tests and evaluated IS6110 PCR for the detection of Mycobacterium tuberculosis (MTB) among clinically diagnosed child TB patients.

METHODS

A total of 102 paediatric patients (<15 years old) with clinically diagnosed TB were enrolled in this study. The patients were admitted to the icddr,b hospital in Dhaka between 2003 and 2005. Sputum/gastric lavage samples were collected for smear microscopy, culture (solid/Lowenstein-Jensen medium and liquid/MGIT), and IS6110 PCR testing. The sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of smear microscopy and PCR were compared to the two culture methods.

RESULTS

Three patients were positive on smear microscopy (2.9%). MTB was detected by conventional culture in 15.7% (16/102), liquid culture in 14% (14/100), and IS6110 PCR in 61.8% (63/102). PCR detected an additional 45 patients who were undetected with the three other tests. Compared to conventional and liquid culture, respectively, smear microscopy showed sensitivity of 18.8% and 21.4%, specificity of 100% individually, PPV of 100% individually, and NPV of 86.9% and 88.7%, whereas PCR had sensitivity of 87.5% and 92.9%, specificity of 43% individually, PPV of 22.2% and 21%, and NPV of 94.9% and 97.4%.

CONCLUSIONS

PCR can be useful compared to smear microscopy and culture methods and is applicable as a rapid screening test for child TB. A larger scale study is required to determine its diagnostic efficacy in improving the detection of child TB in the presence and absence of severe malnutrition.

Serologic Responses in Childhood Pulmonary Tuberculosis

BACKGROUND

Identification of the Mycobacterium tuberculosis immunoproteome and antigens associated with serologic responses in adults has renewed interest in developing a serologic test for childhood tuberculosis (TB). We investigated IgG antibody responses against M. tuberculosis antigens in children with well-characterized TB.

METHODS

We studied archived sera obtained from hospitalized children with suspected pulmonary TB, and classified as having confirmed TB (culture-confirmed), unlikely TB (clinical improvement without TB treatment), or unconfirmed TB (all others). A multiplexed bead-based assay for IgG antibodies against 119 M. tuberculosis antigens was developed, validated and used to test sera. The area under the curves (AUCs) of the empiric receiver-operator characteristic curves were generated as measures of predictive ability. A cross-validated generalized linear model was used to select the most predictive combinations of antigens.

RESULTS

For the confirmed TB versus unlikely TB comparison, the maximal single antigen AUC was 0.63, corresponding to sensitivity 0.60 and specificity 0.60. Older (age: 60+ months old) children's responses were better predictive of TB status than younger (age: 12-59 months old) children's, with a maximal single antigen AUC of -0.76. For the confirmed TB versus unlikely TB groups, the most predictive combinations of antigens assigned TB risk probabilities of 0.33 and 0.33, respectively, when all ages were considered, and 0.57 (interquartile range: 0.48-0.64) and 0.35 (interquartile range: 0.32-0.40) when only older children were considered.

CONCLUSION

An antigen-based IgG test is unlikely to meet the performance characteristics required of a TB detection test applicable to all age groups.

Effectiveness of WHO's pragmatic screening algorithm for child contacts of tuberculosis cases in resource-constrained settings: a prospective cohort study in Uganda

BACKGROUND

Tuberculosis is a leading cause of global childhood mortality; however, interventions to detect undiagnosed tuberculosis in children are underused. Child contact tracing has been widely recommended but poorly implemented in resource-constrained settings. WHO has proposed a pragmatic screening approach for managing child contacts. We assessed the effectiveness of this screening approach and alternative symptom-based algorithms in identifying secondary tuberculosis in a prospectively followed cohort of Ugandan child contacts.

METHODS

We identified index patients aged at least 18 years with microbiologically confirmed pulmonary tuberculosis at Old Mulago Hospital (Kampala, Uganda) between Oct 1, 1995, and Dec 31, 2008. Households of index patients were visited by fieldworkers within 2 weeks of diagnosis. Coprevalent and incident tuberculosis were assessed in household contacts through clinical, radiographical, and microbiological examinations for 2 years. Disease rates were compared among children younger than 16 years with and without symptoms included in the WHO pragmatic guideline (presence of haemoptysis, fever, chronic cough, weight loss, night sweats, and poor appetite). Symptoms could be of any duration, except cough (>21 days) and fever (>14 days). A modified WHO decision-tree designed to detect high-risk asymptomatic child contacts was also assessed, in which all asymptomatic contacts were classified as high risk (children younger than 3 years or immunocompromised [HIV-infected]) or low risk (aged 3 years or older and immunocompetent [HIV-negative]). We also assessed a more restrictive algorithm (ie, assessing only children with presence of chronic cough and one other tuberculosis-related symptom).

FINDINGS

Of 1718 household child contacts, 126 (7%) had coprevalent tuberculosis and 24 (1%) developed incident tuberculosis, diagnosed over the 2-year study period. Of these 150 cases of tuberculosis, 95 (63%) were microbiologically confirmed with a positive sputum culture. Using the WHO approach, 364 (21%) of 1718 child contacts had at least one tuberculosis-related symptom and 85 (23%) were identified as having coprevalent tuberculosis, 67% of all coprevalent cases detected (diagnostic odds ratio 9·8, 95% CI 6·8-14·5; p<0·0001). 1354 (79%) of 1718 child contacts had no symptoms, of whom 41 (3%) had coprevalent tuberculosis. The WHO approach was effective in contacts younger than 5 years: 70 (33%) of 211 symptomatic contacts had coprevalent disease compared with 23 (6%) of 367 asymptomatic contacts (p<0·0001). This approach was also effective in contacts aged 5 years and older: 15 (10%) of 153 symptomatic contacts had coprevalent disease compared with 18 (2%) of 987 asymptomatic contacts (p<0·0001). More coprevalent disease was detected in child contacts recommended for screening when the study population was restricted by HIV-serostatus (11 [48%] of 23 symptomatic HIV-seropositive child contacts vs two [7%] of 31 asymptomatic HIV-seropositive child contacts) or to only culture-confirmed cases (47 [13%] culture confirmed cases of 364 symptomatic child contacts vs 29 [2%] culture confirmed cases of 1354 asymptomatic child contacts). In the modified algorithm, high-risk asymptomatic child contacts were at increased risk for coprevalent disease versus low-risk asymptomatic contacts (14 [6%] of 224 vs 27 [2%] of 1130; p=0·0021). The presence of tuberculosis infection did not predict incident disease in either symptomatic or asymptomatic child contacts: in symptomatic contacts, eight (5%) of 169 infected contacts and six (5%) of 111 uninfected contacts developed incident tuberculosis (p=0·80). Among asymptomatic contacts, incident tuberculosis occurred in six (<1%) of 795 contacts infected at baseline versus four (<1%) of 518 contacts uninfected at baseline, respectively (p=1·00).

INTERPRETATION

WHO's pragmatic, symptom-based algorithm was an effective case-finding tool, especially in children younger than 5 years. A modified decision-tree identified 6% of asymptomatic child contacts at high risk for subclinical disease. Increasing the feasibility of child-contact tracing using these approaches should be encouraged to decrease tuberculosis-related paediatric mortality in high-burden settings, but this should be partnered with increasing access to microbiological point-of-care testing.

FUNDING

National Institutes of Health, Tuberculosis Research Unit, AIDS International Training and Research Program of the Fogarty International Center, and the Center for AIDS Research.

Tuberculosis

Tuberculosis (TB) is currently the world's leading cause of infectious mortality. Imaging plays an important role in the management of this disease. The complex immune response of the human body to Mycobacterium tuberculosis results in a wide array of clinical manifestations, making clinical and radiological diagnosis challenging. ¹⁸F-FDG-PET/CT is very sensitive in the early detection of TB in most parts of the body; however, the lack of specificity is a major limitation. ¹⁸F-FDG-PET/CT images the whole body and provides a pre-therapeutic metabolic map of the infection, enabling clinicians to accurately assess the burden of disease. It enables the most appropriate site of biopsy to be selected, stages the infection, and detects disease in previously unknown sites. ¹⁸F-FDG-PET/CT has recently been shown to be able to identify a subset of patients with latent TB infection who have subclinical disease. Lung inflammation as detected by ¹⁸F-FDG-PET/CT has shown promising signs that it may be a useful predictor of progression from latent to active infection. A number of studies have identified imaging features that might improve the specificity of ¹⁸F-FDG-PET/CT at some sites of extrapulmonary TB. Other PET tracers have also been investigated for their use in TB, with some promising results. The potential role and future perspectives of PET/CT in imaging TB is considered. Literature abounds on the very important role of ¹⁸F-FDG-PET/CT in assessing therapy response in TB. The use of ¹⁸F-FDG for monitoring response to treatment is addressed in a separate review.

Xpert MTB/RIF on Stool Is Useful for the Rapid Diagnosis of Tuberculosis in Young Children With Severe Pulmonary Disease

BACKGROUND

Tuberculosis (TB) continues to result in high morbidity and mortality in children from resource-limited settings. Diagnostic challenges, including resource-intense sputum collection methods and insensitive diagnostic tests, contribute to diagnostic delay and poor outcomes in children. We evaluated the diagnostic utility of stool Xpert MTB/RIF (Xpert) compared with bacteriologic confirmation (combination of Xpert and culture of respiratory samples).

METHODS

In a hospital-based study in Cape Town, South Africa, we enrolled children younger than 13 years of age with suspected pulmonary TB from April 2012 to August 2015. Standard clinical investigations included tuberculin skin test, chest radiograph and HIV testing. Respiratory samples for smear microscopy, Xpert and liquid culture included gastric aspirates, induced sputum, nasopharyngeal aspirates and expectorated sputum. One stool sample per child was collected and tested using Xpert.

RESULTS

Of 379 children enrolled (median age, 15.9 months, 13.7% HIV infected), 73 (19.3%) had bacteriologically confirmed TB. The sensitivity and specificity of stool Xpert versus overall bacteriologic confirmation were 31.9% [95% confidence interval (CI): 21.84%-44.50%] and 99.7% (95% CI: 98.2%-100%), respectively. A total of 23/51 (45.1%) children with bacteriologically confirmed TB with severe disease were stool Xpert positive. Cavities on chest radiograph were associated with Xpert stool positivity regardless of age and other relevant factors [odds ratios (OR) 7.05; 95% CI: 2.16-22.98; P = 0.001].

CONCLUSIONS

Stool Xpert can rapidly confirm TB in children who present with radiologic findings suggestive of severe TB. In resource-limited settings where children frequently present with advanced disease, Xpert on stool samples could improve access to rapid diagnostic confirmation and appropriate treatment.

Taking Costs and Diagnostic Test Accuracy into Account When Designing Prevalence Studies: An Application to Childhood Tuberculosis Prevalence

BACKGROUND

When planning a study to estimate disease prevalence to a pre-specified precision, it is of interest to minimize total testing cost. This is particularly challenging in the absence of a perfect reference test for the disease because different combinations of imperfect tests need to be considered. We illustrate the problem and a solution by designing a study to estimate the prevalence of childhood tuberculosis in a hospital setting.

METHODS

All possible combinations of 3 commonly used tuberculosis tests, including chest X-ray, tuberculin skin test, and a sputum-based test, either culture or Xpert, are considered. For each of the 11 possible test combinations, 3 Bayesian sample size criteria, including average coverage criterion, average length criterion and modified worst outcome criterion, are used to determine the required sample size and total testing cost, taking into consideration prior knowledge about the accuracy of the tests.

RESULTS

In some cases, the required sample sizes and total testing costs were both reduced when more tests were used, whereas, in other examples, lower costs are achieved with fewer tests.

CONCLUSION

Total testing cost should be formally considered when designing a prevalence study.

Diagnostic Test Accuracy in Childhood Pulmonary Tuberculosis: A Bayesian Latent Class Analysis

Evaluation of tests for the diagnosis of childhood pulmonary tuberculosis (CPTB) is complicated by the absence of an accurate reference test. We present a Bayesian latent class analysis in which we evaluated the accuracy of 5 diagnostic tests for CPTB. We used data from a study of 749 hospitalized South African children suspected to have CPTB from 2009 to 2014. The following tests were used: mycobacterial culture, smear microscopy, Xpert MTB/RIF (Cepheid Inc.), tuberculin skin test (TST), and chest radiography. We estimated the prevalence of CPTB to be 27% (95% credible interval (CrI): 21, 35). The sensitivities of culture, Xpert, and smear microscopy were estimated to be 60% (95% CrI: 46, 76), 49% (95% CrI: 38, 62), and 22% (95% CrI: 16, 30), respectively; specificities of these tests were estimated in accordance with prior information and were close to 100%. Chest radiography was estimated to have a sensitivity of 64% (95% CrI: 55, 73) and a specificity of 78% (95% CrI: 73, 83). Sensitivity of the TST was estimated to be 75% (95% CrI: 61, 84), and it decreased substantially among children who were malnourished and infected with human immunodeficiency virus (56%). The specificity of the TST was 69% (95% CrI: 63%, 76%). Furthermore, it was estimated that 46% (95% CrI: 42, 49) of CPTB-negative cases and 93% (95% CrI: 82; 98) of CPTB-positive cases received antituberculosis treatment, which indicates substantial overtreatment and limited undertreatment.

Molecular Diagnosis of TB in the HIV Positive Population

BACKGROUND

Tuberculosis (TB) remains a major contributor to morbidity and mortality in HIV-positive individuals, causing 1.1 million incident cases and 0.32 million deaths in 2012. Diagnosis of TB is particularly challenging in HIV-coinfected individuals, due to a high frequency of smear-negative disease, atypical presentations, and extrapulmonary TB.

OBJECTIVE

The aim of this article was to review the current literature on molecular diagnostics for TB with an emphasis on the performance of these diagnostic tests in the HIV-positive population.

METHODS

We searched the PubMed database using at least one of the terms TB, HIV, diagnostics, Xpert MTB/RIF, nucleic acid amplification tests, drug susceptibility testing, RNA transcription, and drew on World Health Organization publications.

FINDINGS

With increased focus on reducing TB prevalence worldwide, a new set of tools for diagnosing the disease have emerged. Molecular tools such as Xpert MTB/RIF and line-probe assays are now in use or are being rolled out in many regions. The diagnostic performance of these and other molecular assays are discussed here as they pertain to the HIV-positive population.

CONCLUSIONS

Molecular diagnostics offer a useful addition and at times, alternative, to traditional culture methods for the diagnosis of TB. However, most of these tests suffer from decreased accuracy in the HIV-positive population.

Diagnosis of Pulmonary Tuberculosis in Children: Assessment of the 2012 National Institutes of Health Expert Consensus Criteria

BACKGROUND

The 2012 National Institutes of Health (NIH) consensus criteria for standardized diagnostic categories of pulmonary tuberculosis in children have not been validated. We aimed to assess the NIH diagnostic criteria in children with culture-confirmed pulmonary tuberculosis and those in whom tuberculosis has been excluded.

METHODS

We performed a retrospective analysis of consecutive children hospitalized with suspected pulmonary tuberculosis in Cape Town, South Africa, who were enrolled in a diagnostic study. Children were categorized as definite tuberculosis (culture positive), probable tuberculosis (chest radiograph consistent), possible tuberculosis (chest radiograph inconsistent), or not tuberculosis (improved without tuberculosis treatment). We applied the NIH diagnostic categories to the cohort and evaluated their performance specifically in children with definite tuberculosis and not tuberculosis.

RESULTS

Four hundred sixty-four children (median age, 25.1 months [interquartile range, 13.5-61.5 months]) were included; 96 (20.7%) were HIV infected. Of these, 165 (35.6%) were definite tuberculosis, and 299 (64.4%) were not tuberculosis. If strict NIH symptom criteria were applied, 100 (21.6%) were unclassifiable including 21 (21.0%) with definite pulmonary tuberculosis, as they did not meet the NIH criteria due to short duration of symptoms; 71 (71%) had cough <14 days, 48 (48%) had recent weight loss, and 39 (39%) had fever <7 days. Of 364 classifiable children, there was moderate agreement (κ = 0.48) with 100% agreement for definite tuberculosis and moderate agreement for not tuberculosis (220 [60.4%] vs 89 [24.5%]).

CONCLUSIONS

Entry criteria for diagnostic studies should not be restrictive. Data from this analysis have informed revision of the NIH definitions.

Circulating microRNAs as biomarkers for the early diagnosis of childhood tuberculosis infection

MicroRNAs (miRNAs) are a class of highly conserved, single-stranded RNA molecules (length, 18–25 nt) that regulate the expression of their target mRNAs. Previous studies have demonstrated that miRNAs may be novel biomarkers in the diagnosis of certain diseases. In order to evaluate the diagnostic value of miRNAs in childhood tuberculosis (TB), the circulating miRNA profile was determined using microarray analysis. An miRNA-gene network was constructed to identify closely associated miRNAs and these miRNAs were validated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A receiver operational curve (ROC) was used to evaluate the diagnostic sensitivity and specificity of confirmed miRNAs. The microarray data demonstrated that 29 miRNAs were altered with 15 upregulated and 14 downregulated. The network showed indicated 14 miRNAs that are critical in childhood TB. RT-qPCR validated that miR-1, miR-155, miR-31, miR-146a, miR-10a, miR-125b and miR-150 were downregulated in while miR-29 was upregulated in children with TB compared with uninfected children. The ROC curve data indicated the diagnostic value of single miRNA was as follows: miR-150>miR-146a>miR-125b>miR-31>miR-10a>miR-1>miR-155>miR-29. Notably, a combination of these miRNAs exhibited increased diagnostic value compared with any single miRNA. To the best of our knowledge, the present study is the first to identify the expression profile of circulating miRNAs in childhood TB and demonstrated that miRNAs may be a novel, non-invasive and effective biomarker for the early diagnosis of childhood TB.

PET/CT imaging of Mycobacterium tuberculosis infection

Tuberculosis has a high morbidity and mortality worldwide. Mycobacterium tuberculosis (Mtb) has a complex pathophysiology; it is an aerobic bacillus capable of surviving in anaerobic conditions in a latent state for a very long time before reactivation to active disease. In the latent tuberculosis infection, the individual has no clinical evidence of active disease, but exhibits a hypersensitive response to proteins of Mtb. Only some 5–10 % of latently infected individuals appear to have reactivation of tuberculosis at any one time point after infection, and neither imaging nor immune tests have been shown to predict tuberculosis reactivation reliably. The complex pathology of the organism provides multiple molecular targets for imaging the infection and targeting therapy. Positron emission tomography (PET) integrated with computer tomography (CT) provides a unique opportunity to noninvasively image the whole body for diagnosing, staging and assessing therapy response in many infectious and inflammatory diseases. PET/CT is a powerful noninvasive tool that can rapidly provide three-dimensional views of disease deep within the body and conduct longitudinal assessment over time in one particular patient. Some PET tracers, such as ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG), have been found to be useful in various infectious diseases for detection, assessing disease activity, staging and monitoring response to therapy. This tracer has also been used for imaging tuberculosis. ¹⁸F-FDG PET relies on the glucose uptake of inflammatory cells as a result of the respiratory burst that occurs with infection. Other PET tracers have also been used to image different aspects of the pathology or microbiology of Mtb. The synthesis of the complex cell membrane of the bacilli for example can be imaged with ¹¹C-choline or ¹⁸F-fluoroethylcholine PET/CT while the uptake of amino acids during cell growth can be imaged by 3′-deoxy-3′-[¹⁸F]fluoro-l-thymidine. PET/CT provides a noninvasive and sensitive method of assessing histopathological information on different aspects of tuberculosis and is already playing a role in the management of tuberculosis. As our understanding of the pathophysiology of tuberculosis increases, the role of PET/CT in the management of this disease would become more important. In this review, we highlight the various tracers that have been used in tuberculosis and explain the underlying mechanisms for their use.

Performance of the Interferon Gamma Release Assays in Tuberculosis Disease in Children Five Years Old or Less

Interferon Gamma Release Assays (IGRAs) were developed for the indirect or immunologic diagnosis of tuberculosis infection; however, they have also been used to assist in difficult to diagnose cases of tuberculosis disease in adults, and to a lesser extent, in children, especially in those under 5 years old. We evaluated the utility of using an IGRA in pediatric tuberculosis in younger children in a hospital setting. The diagnostic accuracy of T-SPOT.TB and TST was assessed in 117 children with active tuberculosis and 413 children with respiratory tract infection. Sensitivity and specificity were calculated for the tests used individually and together. Concordance was also calculated. Sensitivity of T-SPOT.TB (82.9%) was higher than TST (78.6% using a 5mm cut-off), especially in children confirmed to have TB. T-SPOT.TB was more specific than TST using a 5mm cut-off (96.1% vs. 70.9%). Combining T-SPOT.TB and TST results improved the sensitivity to 96.6%. In conclusion, the results of the current study indicate that T-SPOT.TB has good sensitivity and specificity, supporting its use among patients of this age. A combination of IGRA and TST would be useful additions to assist in the diagnosis of childhood TB.

Evaluation of Xpert® MTB/RIF Assay in Induced Sputum and Gastric Lavage Samples from Young Children with Suspected Tuberculosis from the MVA85A TB Vaccine Trial

Objective

Diagnosis of childhood tuberculosis is limited by the paucibacillary respiratory samples obtained from young children with pulmonary disease. We aimed to compare accuracy of the Xpert^® MTB/RIF assay, an automated nucleic acid amplification test, between induced sputum and gastric lavage samples from young children in a tuberculosis endemic setting.

Methods

We analyzed standardized diagnostic data from HIV negative children younger than four years of age who were investigated for tuberculosis disease near Cape Town, South Africa [2009–2012]. Two paired, consecutive induced sputa and early morning gastric lavage samples were obtained from children with suspected tuberculosis. Samples underwent Mycobacterial Growth Indicator Tube [MGIT] culture and Xpert MTB/RIF assay. We compared diagnostic yield across samples using the two-sample test of proportions and McNemar’s χ² test; and Wilson’s score method to calculate sensitivity and specificity.

Results

1,020 children were evaluated for tuberculosis during 1,214 admission episodes. Not all children had 4 samples collected. 57 of 4,463[1.3%] and 26 of 4,606[0.6%] samples tested positive for Mycobacterium tuberculosis on MGIT culture and Xpert MTB/RIF assay respectively. 27 of 2,198[1.2%] and 40 of 2,183[1.8%] samples tested positive [on either Xpert MTB/RIF assay or MGIT culture] on induced sputum and gastric lavage samples, respectively. 19/1,028[1.8%] and 33/1,017[3.2%] admission episodes yielded a positive MGIT culture or Xpert MTB/RIF assay from induced sputum and gastric lavage, respectively. Sensitivity of Xpert MTB/RIF assay was 8/30[26.7%; 95% CI: 14.2–44.4] for two induced sputum samples and 7/31[22.6%; 11.4–39.8] [p = 0.711] for two gastric lavage samples. Corresponding specificity was 893/893[100%;99.6–100] and 885/890[99.4%;98.7–99.8] respectively [p = 0.025].

Conclusion

Sensitivity of Xpert MTB/RIF assay was low, compared to MGIT culture, but diagnostic performance of Xpert MTB/RIF did not differ sufficiently between induced sputum and gastric lavage to justify selection of one sampling method over the other, in young children with suspected pulmonary TB.

Trial Registration

ClinicalTrials.gov NCT00953927

Diagnostic accuracy of nucleic acid amplification tests in urine for pulmonary tuberculosis: a meta-analysis

OBJECTIVE

To determine the diagnostic accuracy of tuberculosis (TB) nucleic acid amplification tests (NAATs) in urine samples for individuals with active pulmonary tuberculosis (PTB).

DESIGN

Systematic review and meta-analysis. Electronic databases and reference lists were searched without age or setting restrictions up to May 2015. Eligible articles examined Mycobacterium tuberculosis NAATs in urine samples for PTB diagnosis in patients with sputum culture as the reference standard, and reported sufficient data to separately calculate sensitivity or specificity.

RESULTS

Eight studies, including 1212 participants from seven countries with a mean age ranging from 28 to 48 years, were included. Polymerase chain reaction (PCR) with insertion sequence (IS) 6110, rpoB or cfp32/hf6 as gene targets was used for NAATs. The pooled sensitivity and specificity was respectively 0.55 (95%CI 0.36-0.72) and 0.94 (95%CI 0.78-0.99), with slightly higher sensitivity in human immunodeficiency virus positive individuals, at 0.59 (95%CI 0.20-0.89). Sensitivity was higher in sputum microscopy-positive than -negative individuals. Storage temperatures below -70°C, centrifuge speed <5000 rpm and IS6110 increased sensitivity on meta-regression.

CONCLUSIONS

Urine M. tuberculosis PCR for active PTB diagnosis had high specificity but modest sensitivity (55%). Optimizing specimen handling, gene targets or PCR techniques may improve diagnostic accuracy. Reproducibility data are needed.

Clinical Case Definitions for Classification of Intrathoracic Tuberculosis in Children: An Update

Consensus case definitions for childhood tuberculosis have been proposed by an international expert panel, aiming to standardize the reporting of cases in research focusing on the diagnosis of intrathoracic tuberculosis in children. These definitions are intended for tuberculosis diagnostic evaluation studies of symptomatic children with clinical suspicion of intrathoracic tuberculosis, and were not intended to predefine inclusion criteria into such studies. Feedback from researchers suggested that further clarification was required and that these case definitions could be further improved. Particular concerns were the perceived complexity and overlap of some case definitions, as well as the potential exclusion of children with acute onset of symptoms or less severe disease. The updated case definitions proposed here incorporate a number of key changes that aim to reduce complexity and improve research performance, while maintaining the original focus on symptomatic children suspected of having intrathoracic tuberculosis. The changes proposed should enhance harmonized classification for intrathoracic tuberculosis disease in children across studies, resulting in greater comparability and the much-needed ability to pool study results.

Rapid DNA detection of Mycobacterium tuberculosis-towards single cell sensitivity in point-of-care diagnosis

Although there have been many recent advances in Tuberculosis (TB) detection technologies, there still remains a major need to develop simpler point-of-care techniques. In an effort towards such a diagnostic test for resource-poor settings, we have designed a bioassay based on detecting amplified DNA via bridging flocculation. The assay is cheap, with a sensitivity approaching a single cell of Mycobacterium tuberculosis and the potential for translation into broader applications.

Newer Diagnostic Tests for Pulmonary Tuberculosis in Children

It has been well recognized that the diagnosis of pulmonary tuberculosis in children is often compromised by non-specific symptoms, paucibacillary nature of the disease, and the difficulty in collecting the specimen. Consequently, most tuberculosis cases in children are not confirmed, due to which the estimation of the global burden of tuberculosis in children may be inaccurate. There has also been a common misperception that diagnosis of tuberculosis and collecting respiratory specimen in children is always difficult. Because of this, microbiological confirmation of tuberculosis in young children is not routinely attempted in most endemic areas. With the emergence of HIV-related tuberculosis disease and drug-resistant tuberculosis, the availability of accurate, rapid and child friendly diagnostic tools to identify Mycobacterium tuberculosis in respiratory specimen are urgently required in endemic settings. There have been a large number of studies evaluating new diagnostic tests for tuberculosis in the past decade, but few have been evaluated in children. This review will address the developments in respiratory specimen collection and laboratory diagnostic tests of tuberculosis, with a focus on those that have been evaluated in children.

Blood or Urine IP-10 Cannot Discriminate between Active Tuberculosis and Respiratory Diseases Different from Tuberculosis in Children

Objectives. Interferon-γ inducible protein 10 (IP-10), either in blood or in urine, has been proposed as a tuberculosis (TB) biomarker for adults. This study aims to evaluate the potential of IP-10 diagnostics in children from Uganda, a high TB-endemic country. Methods. IP-10 was measured in the blood and urine concomitantly taken from children who were prospectively enrolled with suspected active TB, with or without HIV infection. Clinical/microbiological parameters and commercially available TB-immune assays (tuberculin skin test (TST) and QuantiFERON TB-Gold In-Tube (QFT-IT)) were concomitantly evaluated. Results. One hundred twenty-eight children were prospectively enrolled. The analysis was performed on 111 children: 80 (72%) of them were HIV-uninfected and 31 (27.9%) were HIV-infected. Thirty-three healthy adult donors (HAD) were included as controls. The data showed that IP-10 is detectable in the urine and blood of children with active TB, independent of HIV status and age. However, although IP-10 levels were higher in active TB children compared to HAD, the accuracy of identifying “active TB” was low and similar to the TST and QFT-IT. Conclusion. IP-10 levels are higher in children with respiratory illness compared to controls, independent of “TB status” suggesting that the evaluation of this parameter can be used as an inflammatory marker more than a TB test.

Tuberculosis in the African continent: A comprehensive review

Tuberculosis continues to be a major global health problem, causing an estimated 8.8 million new cases and 1.45 million deaths annually. New drugs in the 1940s made it possible to beat the disease, and consequently, the number of cases reduced drastically. Fast-forward a few decades, drugresistant strains of varied virulence are reported consistently, disease is again on the rise and the treatment has not kept pace. Tuberculosis is the leading cause of death among HIV-infected persons in many resource-constrained settings however, it is curable and preventable. The unprecedented growth of the tuberculosis epidemic in Africa is attributable to several factors, the most important being the HIV epidemic. Analysis of molecular-based data have shown diverse genetic backgrounds among both drug-sensitive and MDR TB isolates in Africa presumably due to underlying genetic and environmental differences. The good news is that there have been important advances recently in TB drugs and diagnostics. Despite the availability of revolutionary tests that allow for faster diagnosis and of new drugs and regimens that offer better and safer treatment it is now becoming clearer that national efforts on TB control should be enhanced and focus on improving the quality of prevention, diagnosis, treatment and care services; strengthening program management, implementation and supervision. This review is an assessment of the trend in TB in Africa.

A comparison of interferon-γ and IP-10 for the diagnosis of tuberculosis

OBJECTIVE

Interferon-γ and IP-10 release assays are diagnostic tests for tuberculosis infection. We have compared the accuracy of IP-10 and QuantiFERON-TB Gold In-tube [QFT-IT] in Tanzanian children suspected of having active tuberculosis (TB).

METHODS

Hospitalized Tanzanian children with symptoms of TB were tested with the QFT-IT and IP-10 tests and retrospectively classified into diagnostic groups. Adults with confirmed TB were assessed in parallel.

RESULTS

A total of 203 children were included. The median age was 3.0 years (interquartile range: 1.2-7.0), 38% were HIV infected, 36% were aged <2 years, and 58% had a low weight-for-age. IP-10 and QFT-IT test performance was comparable but sensitivity was low: 33% (1 of 3) in children with confirmed TB and 29% (8 of 28) in children with probable TB. Rates of indeterminate responders were high: 29% (59 of 203) for IP-10 and 26% (53 of 203) for QFT-IT. Age <2 years was associated with indeterminate test outcome for both IP-10 (adjusted odds ratio [aOR]: 2.2; P = .02) and QFT-IT (aOR: 2.4; P = .01). TB exposure was associated with positive IP-10 test outcome (aOR: 3.6; P = .01) but not with positive QFT-IT outcome (aOR 1.4; P = .52). In 102 adults, test sensitivity was 80% for both tests (P = .248).

CONCLUSIONS

Although IP-10 and QFT-IT performed well in Tanzanian adults, the tests exhibited an equally poor performance in diagnosing active TB in children. Test performance was especially compromised in young children. Neither test can be recommended for use in hospitalized children in high-burden settings.

Evaluation of the Xpert MTB/RIF assay in gastric lavage aspirates for diagnosis of smear-negative childhood pulmonary tuberculosis

BACKGROUND

The diagnosis of pulmonary tuberculosis (TB) in children presents problems worldwide. The Xpert MTB/RIF assay serves as a useful alternative for the rapid diagnosis of childhood TB, with various clinical specimens.

METHODS

In this study, we evaluated the Xpert for diagnosis of smear-negative childhood pulmonary TB using gastric lavage aspirates (GLA). A total of 211 eligible children with suspected TB were consecutively recruited and had GLA obtained for analysis between October 2012 and October 2013 in Beijing Children's Hospital.

RESULTS

The percentages of TB children in <1 year [Odds ratio (95% confidence interval): 4.66 (1.81-11.97)], >5 years group [2.59 (1.30-5.16)] and of living in a rural region [3.78 (2.02-7.08)] were significantly higher than in control groups. The sensitivity in detecting children with a clinical diagnosis of TB for MGIT and Xpert was 12.1% (95% confidence interval: 9.3-14.9%) and 48.6% (95% confidence interval: 44.4-52.8%), respectively. The statistical analysis revealed that GeneXpert showed significantly better sensitivity than MGIT technology (P < 0.001).

CONCLUSIONS

We conclude that Xpert MTB/RIF assay is an excellent tool for the diagnosis of smear-negative childhood with GLA samples. The high proportion of very low mycobacterial load in the GLA samples from smear-negative TB cases may increase the frequency for obtaining indeterminate RIF resistance results by Xpert. In addition, the age <1 year, >5 years and living in a rural region are all high risk factors for childhood TB cases in China.

Assessment of the novel T-cell activation marker-tuberculosis assay for diagnosis of active tuberculosis in children: a prospective proof-of-concept study

BACKGROUND

The diagnosis of paediatric tuberculosis is complicated by non-specific symptoms, difficult specimen collection, and the paucibacillary nature of the disease. We assessed the accuracy of a novel immunodiagnostic T-cell activation marker-tuberculosis (TAM-TB) assay in a proof-of-concept study to identify children with active tuberculosis.

METHODS

Children with symptoms that suggested tuberculosis were prospectively recruited at the NIMR-Mbeya Medical Research Center in Mbeya, and the Ifakara Health Institute in Bagamoyo, Tanzania, between May 10, 2011, and Sept 4, 2012. Sputum and peripheral blood mononuclear cells were obtained for Mycobacterium tuberculosis culture and performance assessment of the TAM-TB assay. The children were assigned to standardised clinical case classifications based on microbiological and clinical findings.

FINDINGS

Among 290 children screened, we selected a subgroup of 130 to ensure testing of at least 20 with culture-confirmed tuberculosis. 17 of 130 children were excluded because of inconclusive TAM-TB assay results. The TAM-TB assay enabled detection of 15 of 18 culture-confirmed cases (sensitivity 83·3%, 95% CI 58·6-96·4). Specificity was 96·8% (95% CI 89·0-99·6) in the cases that were classified as not tuberculosis (n=63), with little effect from latent tuberculosis infection. The TAM-TB assay identified five additional patients with highly probable or probable tuberculosis, in whom M tuberculosis was not isolated. The median time to diagnosis was 19·5 days (IQR 14-45) for culture.

INTERPRETATION

The sputum-independent TAM-TB assay is a rapid and accurate blood test that has the potential to improve the diagnosis of active tuberculosis in children.

FUNDING

European and Developing Countries Clinical Trials Partnership, German Federal Ministry of Education and Research, and Swiss National Science Foundation.

Nuclear imaging: a powerful novel approach for tuberculosis

Nearly 20 years after the World Health Organization declared tuberculosis (TB) a global public health emergency, TB still remains a major global threat with 8.6 million new cases and 1.3 million deaths annually. Mycobacterium tuberculosis adapts to a quiescent physiological state, and is notable for complex interaction with the host, producing poorly-understood disease states ranging from latent infection to fully active disease. Of the approximately 2.5 billion people latently infected with M. tuberculosis, many will develop reactivation disease (relapse), years after the initial infection. While progress has been made on some fronts, the alarming spread of multidrug-resistant, extensively drug-resistant, and more recently totally-drug resistant strains is of grave concern. New tools are urgently needed for rapidly diagnosing TB, monitoring TB treatments and to allow unique insights into disease pathogenesis. Nuclear bioimaging is a powerful, noninvasive tool that can rapidly provide three-dimensional views of disease processes deep within the body and conduct noninvasive longitudinal assessments of the same patient. In this review, we discuss the application of nuclear bioimaging to TB, including the current state of the field, considerations for radioprobe development, study of TB drug pharmacokinetics in infected tissues, and areas of research and clinical needs that could be addressed by nuclear bioimaging. These technologies are an emerging field of research, overcome several fundamental limitations of current tools, and will have a broad impact on both basic research and patient care. Beyond diagnosis and monitoring disease, these technologies will also allow unique insights into understanding disease pathogenesis; and expedite bench-to-bedside translation of new therapeutics. Finally, since molecular imaging is readily available for humans, validated tracers will become valuable tools for clinical applications.

The epidemiology of childhood tuberculosis in the Netherlands: still room for prevention

Background

The occurrence of tuberculosis (TB) among children has long been neglected as a public health concern. However, any child with TB is a sentinel event indicating recent transmission. Vaccination, early case finding and treatment of those latently infected with TB can prevent cases, severe morbidity and unnecessary death.

Method

The objective of the study was to describe the occurrence of TB events among children in the Netherlands which may be avoided through preventive measures. For this purpose we performed a trend analysis of routine Dutch TB and LTBI (surveillance data in 1993–2012 and a descriptive analysis of children with TB and with LTBI diagnosed in 2005–2012).

Results

Overall childhood TB incidence has declined over the last two decades from 3.6 in 1993 to 1.9 per 100,000 children in 2012. The decline was stronger among Dutch-born children compared to foreign-born children. In 2005–2012 64% of childhood TB cases were detected through active case finding. Foreign-born children with TB were less likely to be detected through active case finding, when not detected through post-entry TB screening. Childhood TB diagnosis was culture confirmed in 68% of passively detected cases and 12% of actively detected cases. Of 1,049 children with LTBI started on preventive treatment in 2005–2012, 90% completed treatment. In 37% of all childhood TB cases there was at least one ‘missed opportunity’ for prevention. Thirty nine percent of child TB patients eligible for BCG were not vaccinated.

Conclusion

Children with TB in the Netherlands are generally detected at an early stage and treatment completion rates are high. However, more TB cases among children can be prevented through enhancing TB case finding and screening and preventive treatment of latent TB infection among migrant children, and improving the coverage of BCG vaccination among eligible risk groups.

Diagnosis of childhood tuberculosis and host RNA expression in Africa

BACKGROUND

Improved diagnostic tests for tuberculosis in children are needed. We hypothesized that transcriptional signatures of host blood could be used to distinguish tuberculosis from other diseases in African children who either were or were not infected with the human immunodeficiency virus (HIV).

METHODS

The study population comprised prospective cohorts of children who were undergoing evaluation for suspected tuberculosis in South Africa (655 children), Malawi (701 children), and Kenya (1599 children). Patients were assigned to groups according to whether the diagnosis was culture-confirmed tuberculosis, culture-negative tuberculosis, diseases other than tuberculosis, or latent tuberculosis infection. Diagnostic signatures distinguishing tuberculosis from other diseases and from latent tuberculosis infection were identified from genomewide analysis of RNA expression in host blood.

RESULTS

We identified a 51-transcript signature distinguishing tuberculosis from other diseases in the South African and Malawian children (the discovery cohort). In the Kenyan children (the validation cohort), a risk score based on the signature for tuberculosis and for diseases other than tuberculosis showed a sensitivity of 82.9% (95% confidence interval [CI], 68.6 to 94.3) and a specificity of 83.6% (95% CI, 74.6 to 92.7) for the diagnosis of culture-confirmed tuberculosis. Among patients with cultures negative for Mycobacterium tuberculosis who were treated for tuberculosis (those with highly probable, probable, or possible cases of tuberculosis), the estimated sensitivity was 62.5 to 82.3%, 42.1 to 80.8%, and 35.3 to 79.6%, respectively, for different estimates of actual tuberculosis in the groups. In comparison, the sensitivity of the Xpert MTB/RIF assay for molecular detection of M. tuberculosis DNA in cases of culture-confirmed tuberculosis was 54.3% (95% CI, 37.1 to 68.6), and the sensitivity in highly probable, probable, or possible cases was an estimated 25.0 to 35.7%, 5.3 to 13.3%, and 0%, respectively; the specificity of the assay was 100%.

CONCLUSIONS

RNA expression signatures provided data that helped distinguish tuberculosis from other diseases in African children with and those without HIV infection. (Funded by the European Union Action for Diseases of Poverty Program and others).