Multiple sampling in one day to optimize smear microscopy in children with tuberculosis in Yemen

Accuracy of upper respiratory tract samples to diagnose Mycobacterium tuberculosis: a systematic review and meta-analysis

BACKGROUND

Pulmonary tuberculosis due to Mycobacterium tuberculosis can be challenging to diagnose when sputum samples cannot be obtained, which is especially problematic in children and older people. We systematically appraised the performance characteristics and diagnostic accuracy of upper respiratory tract sampling for diagnosing active pulmonary tuberculosis.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, Cinahl, Web of Science, Global Health, and Global Health Archive databases for studies published between database inception and Dec 6, 2022 that reported on the accuracy of upper respiratory tract sampling for tuberculosis diagnosis compared with microbiological testing of sputum or gastric aspirate reference standard. We included studies that evaluated the accuracy of upper respiratory tract sampling (laryngeal swabs, nasopharyngeal aspirate, oral swabs, saliva, mouth wash, nasal swabs, plaque samples, and nasopharyngeal swabs) to be tested for microbiological diagnosis of tuberculous (by culture and nucleic acid amplification tests) compared with a reference standard using either sputum or gastric lavage for a microbiological test. We included cohort, case-control, cross-sectional, and randomised controlled studies that recruited participants from any community or clinical setting. We excluded post-mortem studies. We used a random-effects meta-analysis with a bivariate hierarchical model to estimate pooled sensitivity, specificity, and diagnostics odds ratio (DOR; odds of a positive test with disease relative to without), stratified by sampling method. We assessed bias using QUADAS-2 criteria. This study is registered with PROSPERO (CRD42021262392).

FINDINGS

We screened 10 159 titles for inclusion, reviewed 274 full texts, and included 71, comprising 119 test comparisons published between May 13, 1933, and Dec 19, 2022, in the systematic review (53 in the meta-analysis). For laryngeal swabs, pooled sensitivity was 57·8% (95% CI 50·5-65·0), specificity was 93·8% (88·4-96·8), and DOR was 20·7 (11·1-38·8). Nasopharyngeal aspirate sensitivity was 65·2% (52·0-76·4), specificity was 97·9% (96·0-99·0), and DOR was 91·0 (37·8-218·8). Oral swabs sensitivity was 56·7% (44·3-68·2), specificity was 91·3% (CI 81·0-96·3), and DOR was 13·8 (5·6-34·0). Substantial heterogeneity in diagnostic accuracy was found, probably due to differences in reference and index standards.

INTERPRETATION

Upper respiratory tract sampling holds promise to expand access to tuberculosis diagnosis. Exploring historical methods using modern microbiological techniques might further increase options for alternative sample types. Prospective studies are needed to optimise accuracy and utility of sampling methods in clinical practice.

FUNDING

UK Medical Research Council, Wellcome, and UK Foreign, Commonwealth and Development Office.

R, Eley B, Bhattad S. Genetically confirmed chronic granulomatous disease in a Kenyan child: case report

Introduction

We report the first case of genetically confirmed chronic granulomatous disease (CGD) in a Kenyan child.

Clinical findings

A 7-month-old male infant, the only child of non-consanguineous parents, presented with cough, fever, fast breathing, oral thrush, and axillary lymphadenopathy ipsilateral to the Calmette-Guérin bacillus scar. He had been hospitalized 5 weeks prior for severe pneumonia. Plain chest radiography showed bilateral patchy airspace opacification; chest computed tomography revealed multiple large lung nodules and left axillary lymphadenopathy. HIV ELISA was negative; tuberculin skin test was positive; lymph node biopsy macroscopically revealed caseous granulomas seen on histology; isoniazid- and rifampicin-susceptible Mycobacterium tuberculosis complex isolate was detected on the Hain test. First-line anti-tuberculous drugs were added to his empiric treatment comprising piperacillin-tazobactam, amikacin, cotrimoxazole, and fluconazole. He was discharged after 10 days based on clinical resolution.

Diagnoses interventions and outcome

An inborn error of immunity (IEI) was considered given the recurrent fevers and atypical lung nodules. Genetic analysis revealed a hemizygous pathogenic variant on CYBB in keeping with X-linked CGD. The child's fevers recurred 2 weeks post-discharge but completely resolved on prophylactic itraconazole and cotrimoxazole. He underwent a successful haplo-identical hematopoietic stem cell transplantation at an experienced center in India with his father as the donor and is currently doing well on post-transplant follow-up.

Conclusion

Genetic testing is relatively accessible and cost-effective for the diagnosis of IEI in low-and-middle-income countries. Expert multi-disciplinary collaboration is key for successful outcomes.

Standardization of a stool concentration method for Mycobacterium tuberculosis detection in the pediatric population

Background

The inability of young children to expectorate sputum and paucibacillary status of Mycobacterium tuberculosis (MTB) increases its diagnostic complexity. In this study, we aimed to standardize a stool concentration method for the detection of MTB and its drug resistance by line probe assay (LPA).

Methods

The stool from 10 healthy children spiked with H37Rv in five different dilutions (1:1, 1:10, 1:100, 1:1000, and 1:10,000), and stool from 10 confirmed TB and 54 clinically diagnosed TB children were subjected to an in-house stool concentration protocol. All the processed filtrates were subjected to smear microscopy, solid culture, Xpert ultra testing, and LPA.

Results

Of 10 control samples, growth was seen in four samples (neat 1:1). In smear microscopy, bacilli could be seen in eight samples (1:1 and 1:10). Xpert ultra testing could detect MTB in eight samples in all dilutions with different loads. LPA could detect MTB in all samples and dilutions. In microbiologically confirmed children, seven out of 10 stool samples tested were positive. Out of 54 children with clinically diagnosed TB, 4 (7.4%) could be confirmed by microbiological diagnosis.

Conclusion

The protocol standardized in this study proves to be better working in the molecular detection of MTB.

Improving the diagnosis of pulmonary tuberculosis using line probe assay and determining the factors associated with the disease in children in Jos, Nigeria

Introduction

Diagnosing tuberculosis (TB), including pulmonary tuberculosis (PTB), in children remains a challenge, partly due to its paucibacillary nature in young children. Data on the use of line probe assay (LPA), on gastric and sputum samples, for diagnosing PTB in children are scarce. We determined the proportion of samples positive for Mycobacterium tuberculosis (MTB) by smear microscopy (SM) and LPA in presumptive PTB cases as well as the factors associated with PTB confirmed by LPA, in children in Jos, Nigeria.

Methods

An observational study in children aged 6 months-16 years. Gastric and sputum samples were examined by SM and by LPA for MTB using GenoType MTBDRplus Ver 2.0 (Hain Lifescience). Multivariate logistic regression was performed to determine the factors associated with PTB.

Results

Out of 103 children with presumptive PTB, 47 had confirmed PTB, 26 unconfirmed PTB and 30 unlikely PTB by LPA. In 67 gastric samples, MTB was identified by SM in 2 (3.0%) compared to 28 (41.8%) by LPA while in 31 sputum samples, MTB was identified by SM in 5 (16.1%) compared to 18 (58.1%) by LPA. The factors associated with pulmonary tuberculosis were an abnormal chest X-ray (adjusted odds ratio (AOR))=12.39 [3.75-40.90], p<0.001), sleeping in the same room with more than three persons (AOR=3.30 [1.23-8.85], p=0.018) and sleeping in a room with none or one window (AOR=2.86 [1.03-7.95], p=0.044).

Conclusions

Line probe assay improves the diagnosis of pulmonary TB in children, especially with gastric samples, while an abnormal chest X-ray is a useful adjunct in PTB diagnosis. Avoiding overcrowding and having windows in sleeping rooms are a necessary part of TB prevention.

Advances in the diagnosis of pulmonary tuberculosis in children

Major challenges still exist in the accurate diagnosis of tuberculosis in children. Algorithms based on clinical and radiological features remain in widespread use despite poor performance. Newer molecular diagnostics allow for rapid identification of TB and detection of drug-resistance in a subset of children, but lack sensitivity. Molecular testing of multiple specimens, including non-traditional specimen types, such as nasopharyngeal aspirates and stool and urine, may improve sensitivity, but the optimal combination of specimens requires further research. Novel tests under development or evaluation include a urine lipoarabinomannan test with improved sensitivity and a range of biomarkers measured from stimulated or unstimulated peripheral blood.

Adolescent tuberculosis

Adolescence is characterised by a substantial increase in the incidence of tuberculosis, a known fact since the early 20th century. Most of the world's adolescents live in low-income and middle-income countries where tuberculosis remains common, and where they comprise a quarter of the population. Despite this, adolescents have not yet been addressed as a distinct population in tuberculosis policy or within tuberculosis treatment services, and emerging evidence suggests that current models of care do not meet their needs. This Review discusses up-to-date information about tuberculosis in adolescence, with a focus on the management of infection and disease, including HIV co-infection and rifampicin-resistant tuberculosis. We outline the progress in vaccine development and highlight important directions for future research.

QuantiFERON-TB Performs Better in Children, Including Infants, than in Adults with Active Tuberculosis: a Multicenter Study

Immunological tests, including the QuantiFERON-TB Gold In-Tube (QFT-IT) assay, represent an important aid for diagnosing active tuberculosis (TB) and latent TB infections in children, but concerns about their use in children <5 years of age persist. This is a multicenter retrospective study comparing a population of 226 children to 521 adults with pulmonary or extrapulmonary TB. The aim was to evaluate the QFT-IT performance, analyzing both qualitative and quantitative results, according to age, birthplace, and disease localization. Compared to culture, QFT-IT sensitivity was 93.9%, 100%, and 94.4% in children ≤2, 2 to 5, and 5 to 16 years of age, respectively, and was significantly higher than that in adults (81.0%) (P < 0.0001). The rate of indeterminate test results for children (2.2%) was significantly lower than that for adults (5.2%) (P < 0.0001). In children, QFT-IT sensitivity was not affected by disease localization or birthplace (Italy born versus foreign born). Interferon gamma (IFN-γ) values in response to TB antigen and mitogen were significantly higher in children than in adults (TB antigen, median of 10 versus 1.66 IU IFN-γ/ml; mitogen, median of 10 versus 6.70 IU IFN-γ/ml; P < 0.0001). In summary, this study supports the use of QFT-IT as a complementary test for the diagnosis of pediatric TB even under 2 years of age. Our observations could be applicable to the new version of the test, QuantiFERON-TB Gold Plus, which has recently been shown to have similar sensitivity in active TB, although data in children are still lacking.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

Specimen Pooling as a Diagnostic Strategy for Microbiologic Confirmation in Children with Intrathoracic Tuberculosis

Three-hundred four young children with suspected pulmonary tuberculosis had a gastric aspirate, induced sputum and nasopharyngeal aspirate collected on each of 2 consecutive weekdays. Specimens collected on the second day were pooled in the laboratory for each child individually. The diagnostic yield by Xpert and culture from pooled specimens was not significantly different to a single gastric aspirate.

Tuberculosis and HIV-An Update on the "Cursed Duet" in Children

HIV and tuberculosis (TB) often occur together with each exacerbating the other. Improvements in vertical transmission prevention has reduced the number of HIV-infected children being born and early antiretroviral therapy (ART) protects against tuberculosis. However, with delayed HIV diagnosis, HIV-infected infants often present with tuberculosis co-infection. The number of HIV exposed uninfected children has increased and these infants have high exposure to TB and may be more immunologically vulnerable due to HIV exposure in utero. Bacillus Calmette-Guérin (BCG) immunization shortly after birth is essential for preventing severe TB in infancy. With early infant HIV diagnosis and ART, disseminated BCG is no longer an issue. TB prevention therapy should be implemented for contacts of a source case and for all HIV-infected individuals over a year of age. Although infection can be identified through skin tests or interferon gamma release assays, the non-availability of these tests should not preclude prevention therapy, once active TB has been excluded. Therapeutic options have moved from isoniazid only for 6-9 months to shorter regimens. Prevention therapy after exposure to a source case with resistant TB should also be implemented, but should not prevent pivotal prevention trials already under way. A microbiological diagnosis for TB remains the gold standard because of increasing drug resistance. Antiretroviral therapy for rifampicin co-treatment requires adaptation for those on lopinavir-ritonavir, which requires super-boosting with additional ritonavir. For those with drug resistant TB, the main problems are identification and overlapping toxicity between antiretroviral and anti-TB therapy. In spite of renewed focus and improved interventions, infants are still vulnerable to TB.

Quantitative Analysis of Gamma Interferon Release Assay Response in Children with Latent and Active Tuberculosis

The use of interferon gamma (IFN-γ) release assays (IGRAs) for the diagnosis of tuberculosis (TB) infection in children is still under debate because of concerns about the immature immune response in children. The aim of this study was to investigate quantitative values of the QuantiFERON-TB Gold In-Tube (QFT-IT) test, a commercially available IGRA, in a large cohort of children screened for TB infection. A retrospective analysis was conducted on samples from 517 children aged 0 to 14 years old at the Pediatric Unit of S. Orsola-Malpighi University Hospital of Bologna (Italy); quantitative responses to QFT-IT stimuli were analyzed according to diagnosis and age. Elevated IFN-γ values in the QFT-IT nil (background) tube were statistically associated with diagnosis of active TB. Quantitative IFN-γ response to Mycobacterium tuberculosis-specific antigens (TB Ag) was not significantly different in children with active TB compared to those with latent TB infection (LTBI), even though the median values were higher in the first group. When children were grouped by age, those less than 5 years old produced significantly higher levels of IFN-γ in response to TB Ag if they had active TB (median 10 IU/ml) than those with LTBI (median 1.96 IU/ml). IFN-γ response to mitogen increased with age. The overall rate of indeterminate results was low (3.9%), and no indeterminate QFT-IT values were observed in active or latent TB patients. In conclusion, quantitative QFT-IT values could provide further information to clinicians to manage TB in children, and these observations could be transferred to the new version of the test, QuantiFERON-TB Gold Plus, which to date lacks data from the pediatric population.

Evaluating treatment outcomes and durations among cases of smear-positive pulmonary tuberculosis in Yemen: a prospective follow-up study

BACKGROUND

Evaluating outcomes after tuberculosis (TB) treatment can help identify the primary reasons for treatment success or failure. However, Yemen has a treatment success rate that remains below the World Health Organization's target. This study aimed to identify factors that were associated with unsuccessful treatment and prolonged treatment (>1 year).

METHOD

Newly diagnosed cases of smear-positive pulmonary TB were prospectively followed at two centers (Taiz and Alhodidah, Yemen) between April 2014 and March 2015. Standardized forms were used to obtain information from the patients regarding their socio-demographic and clinical characteristics, treatment duration, and TB-related information. Multivariate logistic regression analyses were performed to identify factors that were associated with unsuccessful treatment and prolonged treatment (>1 year).

RESULTS

The study included data from 273 cases of newly diagnosed TB, with treatment being successful in 227 cases (83.1%) and unsuccessful in 46 cases (16.9%). Among the 46 patients with unsuccessful treatment, 29 patients (10.6%) stopped treatment, 6 patients (2.2%) transferred to another facility, 6 patients (2.2%) experienced treatment failure, and 5 patients (1.8%) died. The multivariate logistic regression analyses revealed that unsuccessful treatment was associated with female sex, illiterate status, and the presence of comorbidities. Prolonged treatment durations were associated with living in a rural area, smoking, chewing khat, a cough that lasted for >3 weeks at the beginning of treatment, and bilateral cavities during radiography.

CONCLUSION

These results confirm that the treatment success rate in Yemen is lower than the World Health Organization's target for smear-positive pulmonary tuberculosis. Targeting the risk factors that we identified may help improve treatment outcomes. Furthermore, it may not be prudent to re-treat patients using first-line TB drugs after an initial treatment failure.

Stool Culture for Diagnosis of Pulmonary Tuberculosis in Children

Bacteriological confirmation of Mycobacterium tuberculosis is achieved in the minority of young children with tuberculosis (TB), since specimen collection is resource intensive and respiratory secretions are mostly paucibacillary, leading to limited sensitivity of available diagnostic tests. Although molecular tests are increasingly available globally, mycobacterial culture remains the gold standard for diagnosis and determination of drug susceptibility and is more sensitive than molecular methods for paucibacillary TB. We evaluated stool culture as an alternative to respiratory specimens for the diagnosis of suspected intrathoracic TB in a subgroup of 188 children (median age, 14.4 months; 15.4% HIV infected) enrolled in a TB diagnostic study at two local hospitals in Cape Town, South Africa. One stool culture was compared to overall bacteriological confirmation by stool Xpert and by Xpert and culture of multiple respiratory specimens. After decontamination/digestion with NALC (N-acetyl-l-cysteine)-NaOH (1.25%), concentrated fluorescent smear microscopy, Xpert MTB/RIF, and liquid culture were completed for all specimens. Culture contamination of stool specimens was high at 41.5%. Seven of 90 (7.8%) children initiating TB treatment were stool culture positive for M. tuberculosis. Excluding contaminated cultures, the sensitivity of stool culture versus confirmed TB was 6/25 (24.0%; 95% confidence interval [CI] = 9.4 to 45.1%). In addition, stool culture detected TB in 1/93 (1.1%) children with “unconfirmed TB.” Testing the same stool by Xpert increased sensitivity to 33.3% (95% CI = 18.0 to 51.8%). In conclusion, stool culture had low sensitivity for M. tuberculosis detection in children with intrathoracic TB. Reducing culture contamination through improved laboratory protocols may enable more reliable estimates of its diagnostic utility.

Quantiferon-TB Gold In-Tube Improves Tuberculosis Diagnosis in Children

BACKGROUND

The diagnostic accuracy of Quantiferon-TB Gold In-Tube (QFT-IT) is uncertain in the pediatric population, while tuberculin skin test (TST) is still conventionally used despite its limitations. The aim of this study was to compare the performance of QFT-IT with TST in a large cohort of children screened for tuberculosis (TB) infection because of contact tracing, suspected TB, arrival from endemic country or immunosuppressive therapy.

METHODS

A retrospective analysis was conducted on 517 children 0-14 years of age evaluated at the pediatric unit of the S. Orsola-Malpighi University Hospital of Bologna, Italy; 366 of them were also tested with TST. Results were analyzed for Calmette-Guérin bacillus vaccination, country of origin, reason for testing, diagnosis and age.

RESULTS

The overall agreement between the 2 tests was 89.9%, but it was highly affected by Calmette-Guérin bacillus vaccination (P < .0001). According to diagnosis and age, QFT-IT detected latent tuberculous infection cases better than TST in all age groups. Sensitivity for diagnosing active TB in symptomatic children was higher for QFT-IT than TST (93.3% vs. 86.5%), especially in children younger than 2 years, while specificity was high for both tests (99.3% and 98.8%, respectively). Low rate of indeterminate QFT-IT results (3.9%) was not differently distributed among age groups, but was associated with diagnosis of TB exclusion (P < 0.0001), mainly pneumonia (35%), and to Italian children (P = 0.0024).

CONCLUSIONS

Despite the concern about the use of QFT-IT in children because of their immature immune system, our results suggest the preferential use of QFT-IT as a support tool for diagnosis and management of TB, even in infants.

Detection Yield and Tolerability of String Test for Diagnosis of Childhood Intrathoracic Tuberculosis

BACKGROUND

Difficulty to obtain sputum in children complicates diagnosis of intrathoracic tuberculosis (TB). The intragastric string test (ST) used for retrieval of enteric pathogens might be an alternative specimen collection method but requires further evaluation of its utility in TB diagnosis. We conducted a cross-sectional study comparing the TB detection yield and the tolerability of ST and sputum induction (SI) in children.

METHODS

Two ST and SI procedures were performed in children (3-14 years of age) who were clinically suspected of having TB. The string was removed after a 2-hour gastric downtime, and SI was done after a maximum of 20 minutes nebulization with 5% saline solution. LED-fluorescence microscopy and mycobacterial cultures were performed on all specimens, and XpertMTB/RIF assay was performed on stored specimen sediments. Tolerability questionnaires were administered to parents of children.

RESULTS

Of 137 included children (median age: 8.1 years; 33.3% with HIV infection), 14 (10.2%) were diagnosed with TB, 10 (71.4%) by ST and 12 (85.7%) by SI. Among 105 children with both ST and SI performed, 5 (4.8%) versus 4 (3.8%) were smear positive using ST and SI, respectively (McNemar P = 1.00). Nine (8.6%) in each group had positive cultures (P = 1.00). Of 64 children tested with XpertMTB/RIF, 3 (4.7%) of the ST group versus 4 (6.3%) of the SI group were TB positive (P = 1.00). No adverse serious events were reported. ST could not be performed in 22 of 137 (16.1%) children because they were unable to swallow the capsule.

CONCLUSIONS

TB detection yield was comparable between ST and SI. The tolerability of ST in young children might be improved by the reduction of the size of the capsule.

Extensively drug-resistant tuberculosis in a young child after travel to India

Extensively drug-resistant (XDR) tuberculosis is becoming increasingly prevalent worldwide, but little is known about XDR tuberculosis in young children. In this Grand Round we describe a 2-year-old child from the USA who developed pneumonia after a 3 month visit to India. Symptoms resolved with empirical first-line tuberculosis treatment; however, a XDR strain of Mycobacterium tuberculosis grew in culture. In the absence of clinical or microbiological markers, low-radiation exposure pulmonary CT imaging was used to monitor treatment response, and guide an individualised drug regimen. Management was complicated by delays in diagnosis, uncertainties about drug selection, and a scarcity of child-friendly formulations. Treatment has been successful so far, and the child is in remission. This report of XDR tuberculosis in a young child in the USA highlights the risks of acquiring drug-resistant tuberculosis overseas, and the unique challenges in management of tuberculosis in this susceptible population.

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.

Ambulatory gastric lavages provide better yields of Mycobacterium tuberculosis than induced sputum in children with intrathoracic tuberculosis

OBJECTIVE

To compare mycobacterial yield by induced sputum (IS) and gastric lavage (GL), performed on an ambulatory basis in children with probable intrathoracic tuberculosis.

DESIGN

Diagnostic accuracy study.

SETTING

Two tertiary care hospitals in Delhi, India.

PATIENTS

Children aged 6 months to 15 years with newly diagnosed intrathoracic tuberculosis.

METHODS

GL and IS were performed in children on 2 consecutive days on ambulatory basis. Samples were examined by Ziehl-Neelsen staining and cultured on an automated BACTEC-MGIT 960 system.

OUTCOME MEASURE

Mycobacterial yields (smear and culture) for the 2 sample types (IS and GL) were compared.

RESULTS

Four hundred three children (56.6% girls), median age 111 months (interquartile range: 68, 144) were enrolled. Overall yield for acid-fast bacilli and/or Mycobacterium tuberculosis (MTB) by either IS and/or GL was 152 (37.7%). Acid-fast bacilli positivity from IS and GL were 5.7% (23) and 10.4% (42), respectively. Confirmed MTB on culture from IS and GL were 17.9% (72) and 32.5% (127), respectively (P < 0.001). IS and GL identified 17 (4.2%) and 73 (18.1%) additional cases respectively when the other method failed to identify MTB. The combined yields (acid-fast bacilli positivity/MTB) with GL and IS on day 1 (115, 28.5%) were less than that obtained from 2 consecutive GL (135, 33.5%), but better than 2 consecutive IS samples (79, 19.6%; P < 0.001).

CONCLUSION

It is feasible to collect induced sputum and gastric lavage on an ambulatory basis. The yield of MTB obtained by GL is superior to that obtained by IS.

Rapid diagnosis of pulmonary tuberculosis in African children in a primary care setting by use of Xpert MTB/RIF on respiratory specimens: a prospective study

BACKGROUND

In children admitted to hospital, rapid, accurate diagnosis of pulmonary tuberculosis with the Xpert MTB/RIF assay is possible, but no paediatric studies have been done in the primary care setting, where most children are given care, and where microbiological diagnosis is rarely available. We assessed the diagnostic accuracy of Xpert MTB/RIF in children in primary care.

METHODS

For this prospective study, we obtained repeat induced sputum and nasopharyngeal aspirate specimens from children (<15 years) with suspected pulmonary tuberculosis at a clinic in Khayeliwtsha, Cape Town, South Africa. We compared the diagnostic accuracy of Xpert MTB/RIF with a reference standard of culture and smear microscopy on induced sputum specimens. For the main analysis, specificity of Xpert MTB/RIF versus liquid culture, we included only children with two interpretable Xpert MTB/RIF and induced sputum culture results.

FINDINGS

Between Aug 1, 2010, and July 30, 2012, we enrolled 384 children (median age 38·3 months, IQR 21·2-56·5) who had one paired induced sputum and nasopharyngeal specimen, 309 (81%) of whom had two paired specimens. Five children (1%) tested positive for tuberculosis by smear microscopy, 26 (7%) tested positive by Xpert MTB/RIF, and 30 (8%) tested positive by culture. Xpert MTB/RIF on two induced sputum specimens detected 16 of 28 culture-confirmed cases (sensitivity of 57·1%, 95% CI 39·1-73·5) and on two nasopharyngeal aspirates detected 11 of 28 culture-confirmed cases (sensitivity of 39·3, 23·6-57·6; p=0·18). The specificity of Xpert MTB/RIF on induced sputum was 98·9% (95% CI 96·9-99·6) and on nasopharyngeal aspirates was 99·3% (97·4-99·8).

INTERPRETATION

Our findings suggest that Xpert MTB/RIF on respiratory secretions is a useful test for rapid diagnosis of paediatric pulmonary tuberculosis in primary care.

FUNDING

National Institutes of Health, National Health Laboratory Services Research Trust, the Medical Research Council of South Africa, the National Research Foundation South Africa, the European and Developing Countries Clinical Trials Partnership.

Tuberculosis diagnostics for children in high-burden countries: what is available and what is needed

BACKGROUND

The diagnosis of childhood tuberculosis (TB) is complex and most of the new diagnostics for TB are for adults.

AIMS

To review the performance of TB diagnostics and their suitability to its characteristics in young children.

METHODS

Expert opinion and review of the literature.

MAIN FINDINGS

The lack of a sufficient number of research studies on TB diagnostics for children hinders the preparation of systematic literature reviews. Information on test performance in children is often extrapolated from studies in adults and there is a dearth of evidence of test performance in children. Approaches to shorten the time required for diagnosis (by using a variety of specimens) are needed and there is preliminary evidence that such schemes are feasible. Diagnostics based on smear microscopy such as LED-FM, serological tests and IGRAS are unlikely to improve the diagnosis of active TB in children. Liquid and the MODS culture methods are more sensitive than solid culture, and new methods to detect mycobacterium nucleic acid or its components such as TrDNA fragments, LAMP assays and Xpert MTB/RIF have good potential to increase the number of cases confirmed. These tests should be evaluated in specimens which are easily accessible in children such as fine-needle aspiration biopsy, urine, blood and stools.

INTERPRETATION

The evaluation of new diagnostic tests for TB in children is overdue. The lack of suitable diagnostic tests hinders the proper management of children, the assessment of the real burden of childhood TB, evaluation of the efficacy of new treatments and vaccines and, ultimately, the development of effective control interventions.

Evaluation of new strategies for the diagnosis of tuberculosis among pediatric contacts of tuberculosis patients

BACKGROUND

In young children, underdiagnosis and diagnostic delay have an adverse effect on morbidity and mortality of tuberculosis (TB). This study evaluated new strategies for early TB diagnosis using an outpatient protocol in children between 0 and 5 years of age, with a recent household TB contact.

METHODS

Case recruitment was performed in Manaus, Amazonas, Brazil, from 2008 to 2009. Epidemiologic and clinical data, tuberculin test, chest radiograph and 2 induced sputum respiratory samples from each participant were obtained. Laboratory diagnosis was based on Lowenstein-Jensen (LJ) culture, mycobacteria growth indicator tube (MGIT) and polymerase chain reaction. We conducted a study of comparison of diagnostic tests and a study of cases and controls to identify the clinical characteristics of the population with positive culture and polymerase chain reaction results.

RESULTS

A total of 102 children were evaluated. Thirty-two fulfilled criteria of suspicion of TB. MGIT was more sensitive (P = 0.035) and faster (P < 0.001) than LJ. Clinical score, MGIT, LJ and polymerase chain reaction presented no concordance or slight concordance. A positive MGIT culture was only associated with a strong tuberculin test reaction (P = 0.026). The combination of MGIT with the clinical score allowed the diagnosis of 33% more cases with little or no symptomatology compared with the exclusive use of the clinical classification.

CONCLUSIONS

The sensitivity and speed of MGIT demonstrate the utility of liquid cultures for the diagnosis in children. Furthermore, these results suggest that the use of MGIT in children presenting recent household TB contact and a strong tuberculin test reaction may be a strategy to improve early TB diagnosis.

Rapid molecular diagnosis of pulmonary tuberculosis in children using nasopharyngeal specimens

BACKGROUND

A rapid diagnosis of pediatric pulmonary tuberculosis (PTB) using Xpert MTB/RIF (Mycobacterium tuberculosis/rifampicin) automated testing on induced sputum (IS) is possible, but the capacity for performing IS is limited. The diagnosis using a nasopharyngeal aspirate (NPA), which can be non-invasively obtained, is desirable.

METHODS

Paired specimens (NPA and IS) were tested using smear, liquid culture and Xpert. The diagnostic accuracy of Xpert and smear was compared with culture for different specimens in children with suspected PTB.

RESULTS

There were 535 children [median age 19 months, 117 (21·9%) HIV-infected] who had one IS and one NPA specimen; 396 had two paired specimens. A positive smear, Xpert test or culture occurred in 30 (5.6%), 81 (15.1%) and 87 children (16.3%), respectively. The culture yield was higher from IS (84/87, 96.6%) vs NPA (61/87, 70.1%, P < .001). Amongst children with two paired specimens, 63 culture-confirmed cases occurred [60 (95.2%) IS vs 48 (76.2%) NPA, P = .002]. The sensitivity of two Xpert tests was similar for IS and NPAs [(45/63) 71% vs (41/63) 65%, P = .444)]; the sensitivity of smear was lower for IS (21/63, 33%) and NPA (16/63, 25%). The incremental yield from a second IS was 9 cases (17.6%) by culture and 9 (25%) by Xpert testing; a second NPA increased the culture yield by 10 (26.3%) and Xpert by 11 (36.7%). Xpert specificity was 99.1% (98.1-100) for IS and 98.2% (96.8-99.6) for NPAs. Xpert testing provided faster results than culture (median 0 vs 15 days, P < .001).

CONCLUSIONS

Xpert testing on 2 NPAs is useful in children with suspected PTB, particularly in settings where IS and culture are not feasible.

Diagnosis and management of TB in children: an update

In recent years, several notable modifications have occurred in the management of TB infection and disease in children. First, we review new data related to infection, including alternative regimens for the treatment of latent TB, management of drug-resistant infection and preventive therapy in the context of HIV infection. Next, we summarize updated WHO guidelines for the treatment of TB in children, explore issues specific to the management of disease in HIV-infected children, and retreatment of TB, and review pediatric recommendations for the management of drug-resistant TB. Finally, we conclude with a discussion of adjunctive therapy and new drugs in development.

The diagnosis of tuberculosis

Childhood tuberculosis accounts for a significant proportion of the global tuberculosis disease burden. However, tuberculosis in children is difficult to diagnose, because disease tends to be paucibacillary and sputum samples are often not easy to obtain. The diagnosis of tuberculosis in children is traditionally based on chest radiography, tuberculin skin testing, and mycobacterial staining/culture from appropriate samples. Newer diagnostic strategies have included improved bacteriologic and molecular methods, as well as new methods for sample collection from children. Recently, immune-based diagnostics, such as the interferon-gamma release assays, have been introduced for clinical use. These tests do not offer substantial improvements in sensitivity over tuberculin skin testing for the diagnosis of active disease but may be useful in excluding false-positive tuberculin skin tests. Further research is needed to develop better diagnostic tests for tuberculosis in children.

Advances in the diagnosis of pulmonary tuberculosis in HIV-infected and HIV-uninfected children

The identification of improved diagnostic tests for tuberculosis has been identified as a global research priority. Over the past decade, there has been renewed interest in the development and validation of novel diagnostic tools for pulmonary tuberculosis that are applicable to resource-poor settings. These techniques are aimed primarily at improving detection of the organism or a specific host immune response. Although most studies have focused on determining the accuracy of novel tests in adults, it is likely they will also have the capacity to significantly improve the diagnosis of childhood tuberculosis. Improving the quality of clinical samples obtained from children with suspected tuberculosis remains an important research priority while awaiting validation of novel diagnostic tests. This review will focus on a number of recent developments for the diagnosis of tuberculosis, with a specific emphasis on the application of these new tests to children in settings where tuberculosis is endemic.

The urgent need for new diagnostics for symptomatic tuberculosis in children

TB is a major public health problem causing 9 million cases, of which 10%-15% occur in children each year. Historically, children have received lower priority within TB control activities because they are considered less infectious than smear-positive adults. This review argues that TB is a public health problem in children and that poor awareness of the magnitude of the problem emanates from the lack of suitable pediatric diagnostic tests for TB and the characteristics of the disease in young children. New TB diagnostics, approved for use in adults have not been evaluated in children, although there is limited evidence that some of these tests hold promise and should be assessed. There are several approaches that could be used to improve the performance of tests in pediatric patients. These include improved methods for specimen collection and processing. The value of collecting specimens from multiple anatomical sites to shorten the diagnostic process and improve sensitivity was reported recently and the combination of expectorated sputum, nasopharyngeal aspirate, induce sputum and gastric aspirate may result in a similar yield than specimens collected over consecutive days. Methods for sample collection such as fine needle aspiration biopsy should be used more frequently and the Microscopic Observation Drug Sensitivity (MODS) assay has higher sensitivity than LJ culture. There is however very scanty evidence of the performance of other promising tests such as the fully automated NAAT (Xpert) and Line Probe Assays and loop mediated isothermal amplification. Although the future holds promise, increased support from international organizations and funding agencies is needed to promote the evaluation and development of new diagnostics that are suitable for TB in children.

New specimens and laboratory diagnostics for childhood pulmonary TB: progress and prospects

Childhood pulmonary TB (PTB) is under diagnosed, in part due to difficulties in obtaining microbiological confirmation. However, given the poor specificity of clinical diagnosis, microbiological confirmation and drug susceptibility testing is important in guiding appropriate therapy especially in the context of drug resistant TB. Confirmation is often possible, even in infants and young children, if adequate specimens are collected. Culture yield varies with the severity of illness, specimen type and culture method. Induced sputum is recognised as a safe procedure with a high diagnostic yield. Advances include optimised protocols for smear microscopy and modified culture techniques, such as the Microscopic Observation Drug Susceptibility Assay. Detection of Mycobacterium tuberculosis nucleic acid in respiratory specimens has high specificity but relatively poor sensitivity, particularly for smear negative disease. The recent development of an integrated specimen processing and real-time PCR testing platform for M. tuberculosis and rifampicin resistance is an important advance that requires evaluation in childhood TB.