Detection of Mycobacterium tuberculosis in nasopharyngeal aspirate samples in children

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

Contribution and Acceptability of Bacteriological Collection Tools in the Diagnosis of Tuberculosis in Children Infected with HIV

OBJECTIVE

The objective of this study is to evaluate the feasibility and tolerability of new bacteriological samples to diagnose tuberculosis (TB) in HIV-infected children.

METHOD AND PATIENTS

HIV1-infected children with suspicion of TB in Universitary Hospital Sourô Sanon (Burkina Faso) were included in a prospective cohort study. Children underwent three gastric aspirates (GA) if aged <4 years; two GA, one string test (ST) if aged 4-9 years and three sputum, one ST if aged 10-13 years. All children underwent one nasopharyngeal aspirate (NPA) and one stool sample. To assess feasibility and tolerability of procedures, adverse events were identified and pain was rated on different scales. Samples were tested by microscopy, culture, GeneXpert® (Xpert®).

RESULTS

Sixty-three patients were included. Mean age was 8.92 years, 52.38% were females. Ninety-five GA, 67 sputum, 62 NPA, 60 stool and 55 ST had been performed. During sampling, the main adverse events were cough at 68/95 GA and 48/62 NPA; sneeze at 50/95 GA and 38/62 NPA and vomiting at 4/55 ST. On the behavioral scale, the average pain score during collection was 6.38/10 for GA; 7.70/10 for NPA and 1.03/10 for ST. Of the 31 cases of TB, bacteriological confirmation was made in 12 patients.

CONCLUSION

ST, stool is well-tolerated alternatives specimens for diagnosing TB in children. NPA has a poor feasibility and tolerability in children.

Tuberculosis Diagnosis in Children Using Xpert Ultra on Different Respiratory Specimens

Rationale: Microbiological confirmation of pulmonary tuberculosis in children is desirable.Objectives: To investigate the diagnostic accuracy and incremental yield of Xpert MTB/RIF Ultra (Ultra; Cepheid), a new rapid test, on repeated induced sputum, nasopharyngeal aspirates, and combinations of specimens.Methods: Consecutive South African children hospitalized with suspected pulmonary tuberculosis were enrolled.Measurements and Main Results: Induced sputum (IS) and nasopharyngeal aspirates (NPAs) were obtained. NPAs were frozen; IS underwent liquid culture, and an aliquot was frozen. Ultra was performed on thawed NPAs and IS specimens individually. Children were categorized as confirmed, unconfirmed, or unlikely tuberculosis according to NIH consensus case definitions. The diagnostic accuracy of Ultra was compared with liquid culture on IS. In total, 195 children (median age: 23.3 mo; 32 [16.4%] HIV-infected) had one IS and NPA, and 130 had two NPAs. There were 40 (20.5%) culture-confirmed cases. Ultra was positive on NPAs in 26 (13.3%) and on IS in 31 (15.9%). Sensitivity and specificity of Ultra on one NPA were 46% and 98%, respectively, and similar by HIV status. Sensitivity and specificity of Ultra on one IS were 74.3% and 96.9% respectively. Combining one NPA and one IS increased sensitivity to 80%. Sensitivity using Ultra on two NPAs was 54.2%, increasing to 87.5% with an IS Ultra.Conclusions: IS provides a better specimen than repeated NPA for rapid diagnosis using Ultra. However, Ultra testing of combinations of specimens provides a novel strategy that can be adapted to identify most children with confirmed pulmonary tuberculosis.

Utility of urine as a clinical specimen for the diagnosis of pulmonary tuberculosis in people living with HIV in Addis Ababa, Ethiopia

Background

Tuberculosis is a common cause of mortality and morbidity among people living with HIV/AIDS. Despite the increased prognosis of tuberculosis among HIV infected patients, diagnosis of pulmonary tuberculosis (PTB) smear microscopy has a low sensitivity due to low bacterial load in a sputum specimen of HIV patients. Having alternative specimens for increasing detection of Mycobacterium tuberculosis (Mtb) is very important.

Objective

The aim of this study was to evaluate the efficacy of urine as clinical specimen for the diagnosis of pulmonary tuberculosis in people living with HIV.

Method

A total of 117 HIV-seropositive individuals from three public health facilities in Addis Ababa, Ethiopia were enrolled consecutively from December 2013 to July 2014. A total of 117 paired morning sputum and urine samples were simultaneously collected from anti-retroviral therapy (ART) naïve PTB suspected individuals living with HIV. Both sputum and urine samples were processed for culture using Lowenstein-Jensen medium, and the left was subjected to PCR using RD9 primers. Chi-square test and kappa value were used to compare different methods used.

Result

Out of 117 suspected PTB HIV-infected people, sputum culture alone detected more mycobacterial isolates 33 (28.2%) than the urine specimen alone 17 (14.5%). Of the 33 patients positive for sputum culture, 13 patients were observed as a urine culture positive. Of the 84 individuals negative for mycobacterial by sputum culture, four (4.8%) were urine culture positive and thus, the sensitivity, and the agreement between urine culture as compare to sputum culture were 39.4% and 0.49, respectively. On the other hand, the sensitivity of RD9-based PCR directly on urine was 72.7% by considering sputum culture as a reference standard. Moreover, RD9-based PCR directly on sputum detected 9 (7.7%) individuals who were sputum culture negative for M. Tuberculosis. The detection rate of M. tuberculosis from urine in patients those who couldn't produce sputum were 9(34.6%).

Conclusion

PCR and culture examination of urine samples also can improve the detection rate of M. tuberculosis in PTB suspected HIV positive individuals.

Newer Diagnostic Tests and their Application in Pediatric TB

The diagnosis of childhood tuberculosis is a challenge due to the pauci-bacillary nature of infection and the difficulty in obtaining appropriate sample. In the past 2-3 decades, many new tests were introduced for the diagnosis of tuberculosis (TB) and some of them have been evaluated for their application in pediatric tuberculosis as well. There is an attempt to improve smear microscopy by introducing light-emitting diode (LED) fluorescence microscopy and there are also some automated digital microscopy platforms under evaluation. Introduction of automated liquid culture platform along with rapid molecular based identification methods have considerably reduced the time delay in mycobacterial culture. Recent addition of many nucleic acid amplification platforms like Amplicor PCR, Genprobe, Xpert MTB/Rif, line probe assays, loop mediated isothermal amplification etc are also been found to be useful. Latest techniques like microarray and gene sequencing are also being used in clinical laboratories with variable results. Indirect methods of TB diagnosis like T cell based assays including tuberculin skin test and interferon-gamma release assays have their role primarily in the diagnosis of latent TB. Biomarkers are the latest addition in the battery of TB diagnostic tests facilitating diagnosis using easily accessible samples like urine, blood and breath of patients. Many biomarkers are still under evaluation and some of them are found to have a potential role as promising diagnostic tests of future.

Detection of Mycobacterium tuberculosis from the stool of HIV sero-positive individuals suspected of pulmonary tuberculosis

BACKGROUND

The impact of tuberculosis (TB) is exacerbated in Africa because of the human immunodeficiency virus (HIV) pandemic. Pulmonary tuberculosis (PTB) diagnosis is difficult in HIV-infected patients and negative sputum results are more common which leads to diagnostic delay and increases morbidity and mortality. Extra-pulmonary samples such as stool may be easier to obtain and our approach may therefore significantly improve PTB detection in people living with HIV.

OBJECTIVE

To detect Mycobacterium tuberculosis from the stool of HIV sero-positive individuals suspected of pulmonary TB.

METHOD

A total of 117 HIV-infected individuals from three public health facilities in Addis Ababa, Ethiopia were enrolled consecutively in the study. Paired morning sputum and stool samples were simultaneously collected from anti-retroviral therapy (ART) naïve individuals living with HIV and suspected for PTB. The diagnostic accuracy of the smear microscopy, culture and region of difference (RD)9-based polymerase chain reaction (PCR) in stool was compared with the accuracy of sputum testing. Chi-square test and kappa value were used to compare different method used.

RESULTS

Sputum culture positivity for mycobacteria was confirmed in 33(28.2%) of the study subjects. Of 33 individuals positive for sputa culture, 10 individuals were observed to be stools culture positive. Of the 84 individuals negative for mycobacteria by sputum culture, three (3.6%) were stool culture positive and thus, the sensitivity and agreement between stool culture as compare to sputum culture were 30.3% and 0.33, respectively. Of 117 individuals, 11(9.4%) were sputum smear positive and of 11 sputum smear positive three were also stool smear positive. While of the 106 sputum smear negative individuals', only one was stool smear positive resulting in 12.1% sensitivity and 0.18 agreements against sputum culture. On the other hand, the sensitivity of RD9-based PCR directly on stool was 69.7% by considering sputum culture as a reference standard. Moreover, RD9-based PCR directly on sputum detected 7(6.0%) individuals who were sputum culture negative for M. tuberculosis.

CONCLUSION

M. tuberculosis was detected in stool of individuals living with HIV who were negative for sputum smear microscopy and culture. Hence, examination of stool samples alongside with sputum samples increases the detection of PTB in individuals living with HIV.

Recommendations for the diagnosis of pediatric tuberculosis

Tuberculosis (TB) is still the world's second most frequent cause of death due to infectious diseases after HIV infection, and this has aroused greater interest in identifying and managing exposed subjects, whether they are simply infected or have developed one of the clinical variants of the disease. Unfortunately, not even the latest laboratory techniques are always successful in identifying affected children because they are more likely to have negative cultures and tuberculin skin test results, equivocal chest X-ray findings, and atypical clinical manifestations than adults. Furthermore, they are at greater risk of progressing from infection to active disease, particularly if they are very young. Consequently, pediatricians have to use different diagnostic strategies that specifically address the needs of children. This document describes the recommendations of a group of scientific societies concerning the signs and symptoms suggesting pediatric TB, and the diagnostic approach towards children with suspected disease.

A Novel Sample Processing Method for Rapid Detection of Tuberculosis in the Stool of Pediatric Patients Using the Xpert MTB/RIF Assay

BACKGROUND

Tuberculosis (TB) is difficult to diagnose in children using molecular tests, because children have difficulty providing respiratory samples. Stool could replace sputum for diagnostic TB testing if adequate sample processing techniques were available.

METHODS

We developed a rapid method to process large volumes of stool for downstream testing by the Xpert MTB/RIF (Xpert) TB-detection assay. The method was tested and optimized on stool samples spiked with known numbers of M. tuberculosis colony forming units (CFU), and stools from M. tuberculosis-infected cynomolgus macaques (Macaca fascicularis). Performance was scored on number of positive Xpert tests, the cycle thresholds (Cts) of the Xpert sample-processing control (SPC), and the Cts of the M. tuberculosis-specific rpoB probes. The method was then validated on 20 confirmed TB cases and 20 controls in Durban, South Africa.

RESULTS

The assay's analytical limit of detection was 1,000 CFU/g of stool. As much as one gram of spiked stool could be tested without showing increased PCR inhibition. In analytical spiking experiments using human stool, 1g samples provided the best sensitivity compared to smaller amounts of sample. However, in Macaques with TB, 0.6g stool samples performed better than either 0.2g or 1.2g samples. Testing the stool of pediatric TB suspects and controls suggested an assay sensitivity of 85% (95% CI 0.6-0.9) and 84% (95% CI 0.6-0.96) for 0.6g and 1.2g stool samples, respectively, and a specificity of 100% (95% CI 0.77-1) and 94% (95% CI 0.7-0.99), respectively.

CONCLUSION

This novel approach may permit simple and rapid detection of TB using pediatric stool samples.

Rapid culture-based diagnosis of pulmonary tuberculosis in developed and developing countries

Culturing Mycobacterium tuberculosis remains the gold standard for the laboratory diagnosis of pulmonary tuberculosis, with 9 million new cases and 1.5 million deaths mainly in developing countries. Reviewing data reported over 20 years yields a state-of-the-art procedure for the routine culture of M. tuberculosis in both developed and developing countries. Useful specimens include sputum, induced sputum, and stools collected in quaternary ammonium preservative-containing sterile cans. The usefulness of other non-invasive specimens remains to be evaluated. Specimens can be collected in a diagnosis kit also containing sampling materials, instructions, laboratory requests, and informed consent. Automated direct LED fluorescence microscopy after auramine staining precedes inoculation of an egg-lecithin-containing culture solid medium under microaerophilic atmosphere, inverted microscope reading or scanning video-imaging detection of colonies and colonies identification by recent molecular methods. This procedure should result in a diagnosis of pulmonary tuberculosis as fast as 5 days. It may be implemented in both developed and developing countries with automated steps replaceable by manual steps depending on local resources.

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.

Intensified specimen collection to improve tuberculosis diagnosis in children from Rural South Africa, an observational study

BACKGROUND

In drug-resistant TB settings, specimen collection is critical for drug-susceptibility testing (DST). This observational study included multiple specimen types collected from pediatric TB suspects with the aim to determine diagnostic yield and inform clinical practice in children with drug-resistant and drug-susceptible TB.

METHODS

From 03/2009-07/2010, TB suspects aged ≥6 months and ≤12 years were recruited among outpatient and inpatient settings. Subjects were new TB suspects or had persistent symptoms despite ≥2 months of TB treatment. The protocol included collection of a single blood and urine specimen, a single sputum induction and, if inpatients and <5 years of age, collection of 3 gastric aspirates (GA). Samples were cultured on solid and/or liquid media. DST was by 1% proportion method.

RESULTS

Among 118 children with possible, probable or confirmed TB, the mean age was 4.9 years [SD 3.2] and 64 (62%) of those tested were HIV-positive. Eight (7%) subjects were culture-positive from at least one specimen; yield did not differ by HIV status or TB treatment history. Among those with positive cultures, 7/8 (88%) were from induced sputum, 5/6 (83%) from GA, 3/8 (38%) from blood, and 3/7 (43%) from urine. In subjects with both induced sputum and GA collection, sputum provided one additional case compared to GA. Multidrug resistant (MDR)-TB was detected by urine culture alone in one child >5 years old. Pan-resistant extensively drug resistant (XDR)-TB was identified by cultures from all sites in one subject.

CONCLUSIONS

TB was cultured from HIV-positive and -negative children, and allowed for identification of MDR and XDR-TB cases. Urine and induced sputum each provided an additional TB diagnosis and, when compared to GA, may be considered a less invasive, same-day method of specimen collection for childhood TB suspects. This study illustrates the continued challenges and limitations of available strategies for pediatric TB diagnostics.

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.

Childhood TB: when to think of it and what to do when you do

Although childhood tuberculosis has declined dramatically in the UK over the last century, it is now increasing again and globally childhood tuberculosis still accounts for a significant proportion of the tuberculosis disease burden. Children may present with non-specific symptoms, and because of the paucibacillary nature of disease and the difficulty of producing sputum samples, tuberculosis in children is often difficult to diagnose. Apart from the traditional diagnostic methods, like chest X-ray, tuberculin skin testing and mycobacterial staining or culture, new diagnostic strategies have been developed. In particular, immune-based diagnostics, such as interferon-gamma release assays, have now been introduced for clinical use. However these tests do not offer substantial improvements in sensitivity over tuberculin skin testing for the diagnosis of active disease. Further research is needed to develop better diagnostic tests for tuberculosis in children.

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.

Does neutralization of gastric aspirates from children with suspected intrathoracic tuberculosis affect mycobacterial yields on MGIT culture?

The microbiological confirmation of pulmonary tuberculosis in children relies on cultures of gastric aspirate (GA) specimens. Conventionally, GAs are neutralized to improve culture yields of mycobacteria. However, there are limited data to support this practice. To study the utility of neutralization of GAs with sodium bicarbonate in children with intrathoracic tuberculosis, a total of 116 children of either sex, aged 6 months to 14 years (median age, 120 months; interquartile range [IQR], 7 to 192 months), underwent gastric aspiration on 2 consecutive days. Gastric aspirates were divided into two aliquots, and only one aliquot was neutralized with 1% sodium bicarbonate. Both aliquots were processed for smear and culture examinations. Out of the 232 gastric aspirates, 12 (5.17%) were acid-fast bacilli (AFB) smear positive. There were no differences in smear positivity rates from samples with or without neutralization. The yield of Mycobacterium tuberculosis on a Bactec MGIT 960 culture system was significantly lower in the neutralized samples (16.3% [38/232]) than in the nonneutralized samples (21.5% [50/232]) (P = 0.023). There was no significant difference between the neutralized and the nonneutralized samples in time to detection using the MGIT 960 system (average, 24.6 days; IQR, 12 to 37 days) (P = 0.9). The contamination rates were significantly higher in the neutralized samples than in the nonneutralized samples (17.2% [40/232] versus 3.9% [9/232]) (P = 0.001). The agreement for positive mycobacterial culture between the two approaches was 66.5% (P = 0.001). Hence, we recommend that gastric aspirate samples not be neutralized with sodium bicarbonate prior to culture for M. tuberculosis.

Promising directions in the diagnosis of childhood tuberculosis

Estimates of the burden of childhood tuberculosis have been hampered by the lack of a reliable diagnostic test. Clinical scoring systems, radiological findings and tuberculin skin testing (the traditional methods used for diagnosis) are unreliable, particularly in the era of HIV. Microbiologic confirmation using induced sputum is feasible and has become increasingly important to define the burden of disease and to enable appropriate treatment. The availability of a rapid molecular diagnostic test (Xpert® MTB/RIF; Cepheid) is an important advance that can improve case detection in children and enable rapid detection of mycobacterial drug resistance. Xpert testing of two induced sputum specimens detected approximately 75% of children with culture-confirmed disease. Urine lipoarabinomannan has shown promise as a rapid diagnostic in a subgroup of HIV-infected severely immunocompromised adults, but there have been no data in children so far. Further research is needed to develop a rapid point-of-care, reliable and affordable diagnostic test for childhood tuberculosis that can be widely used.

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.

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.

TB and HIV in children - advances in prevention and management

The human immunodeficiency virus (HIV) epidemic has had a major impact on the age and gender profile of adult tuberculosis (TB) patients, resulting in increased exposure of HIV-infected and uninfected children at a very young age. Young and/or HIV-infected children are extremely vulnerable to develop severe forms of TB following recent exposure and infection. There is an urgent need to implement safe and pragmatic strategies to prevent TB in children, especially in TB endemic areas where they suffer the greatest burden of disease. The management of TB in HIV-infected children poses multiple challenges, but recent advances in the implementation of prevention of mother to child transmission (PMTCT) strategies and HIV care of infants offer hope. These include HIV testing and access to PMTCT for all pregnant women, routine testing of all HIV exposed infants and rapid initiation of antiretroviral treatment irrespective of clinical or immunological disease staging. In addition, careful scrutiny for TB exposure should occur at every health care visit, with provision of isoniazid preventive therapy (IPT) following each documented exposure event. Knowing the HIV infection status of child TB suspects is essential to optimize case management. Although multiple difficulties remain, recent advances demonstrate that the management of children with TB and/or HIV can be vastly improved by well focused interventions using readily available resources.

How to optimize current (available) diagnostic tests

Isolation of mycobacterium tuberculosis is the gold standard in the diagnosis of childhood tuberculosis. However, it has inherent limitations due to paucibacillary nature of the disease in children and technical difficulties encountered in collection of appropriate sample. Thus, diagnosis is dependent on circumstantial evidence at best supported by conventional tests such as tuberculin test and chest radiograph. Several new tests are being developed but they lack ideal sensitivity and specificity. Hence, it is important to optimise use of current diagnostic tests. Clinical suspicion based on protocol developed by IAP is a pre-requisite of ordering tests and it is only then that proper interpretation is possible. Tuberculin skin test is still a useful screening test. It does help in establishing presence of infection though not necessarily disease. Attention must be paid to ideal test solution, proper technique and cautious interpretation. BCG test is not recommended. Miliary shadows and fibrocaseious cavitary lesions in chest radiograph are highly suggestive of tuberculosis in our epidemiology. CT scan is rarely necessary and is not cost and radiation-effective. It is ideal to attempt bacteriological examination in every suspected case of childhood tuberculosis. Most practical method is collection of gastric aspirate for smear and culture. It is possible to carry out this procedure in out-patient clinic. Better yield is likely with increasing expertise especially in extensive disease. Bronchoalveolar lavage is an invasive test and bacterial yield is comparable to that of gastric aspirate. Tissue collected for histopathological examination must be submitted for bacteriological tests. PCR is not easily available. It has high sensitivity but lower specificity and thus, is not routinely recommended. Serology has no place in diagnosis of tuberculosis. Interferon gamma release assays are also now available. Sensitivity and specificity of Quantiferon Gold and T-spot tests have not been studied in children and hence are not recommended in routine practice. Instead of trying newer tests, it may be best to avail an expert advice in difficult cases.

Diagnostic approaches for paediatric tuberculosis by use of different specimen types, culture methods, and PCR: a prospective case-control study

BACKGROUND

The diagnosis of pulmonary tuberculosis presents challenges in children because symptoms are non-specific, specimens are difficult to obtain, and cultures and smears of Mycobacterium tuberculosis are often negative. We assessed new diagnostic approaches for tuberculosis in children in a resource-poor country.

METHODS

Children with symptoms suggestive of pulmonary tuberculosis (cases) were enrolled from August, 2002, to January, 2007, at two hospitals in Lima, Peru. Age-matched and sex-matched healthy controls were enrolled from a low-income shanty town community in south Lima. Cases were grouped into moderate-risk and high-risk categories by Stegen-Toledo score. Two specimens of each type (gastric-aspirate, nasopharyngeal-aspirate, and stool specimens) taken from each case were examined for M tuberculosis by auramine smear microscopy, broth culture by microscopic-observation drug-susceptibility (MODS) technique, standard culture on Lowenstein-Jensen medium, and heminested IS6110 PCR. Specimens from controls consisted of one nasopharyngeal-aspirate and two stool samples, examined with the same techniques. This study is registered with ClinicalTrials.gov, number NCT00054769.

FINDINGS

218 cases and 238 controls were enrolled. 22 (10%) cases had at least one positive M tuberculosis culture (from gastric aspirate in 22 cases, nasopharyngeal aspirate in 12 cases, and stool in four cases). Laboratory confirmation of tuberculosis was more frequent in cases at high risk for tuberculosis (21 [14.1%] of 149 cases with complete specimen collection were culture positive) than in cases at moderate risk for tuberculosis (one [1.6%] of 61). MODS was more sensitive than Lowenstein-Jensen culture, diagnosing 20 (90.9%) of 22 patients compared with 13 (59.1%) of 22 patients (p=0.015), and M tuberculosis isolation by MODS was faster than by Lowenstein-Jensen culture (mean 10 days, IQR 8-11, vs 25 days, 20-30; p=0.0001). All 22 culture-confirmed cases had at least one culture-positive gastric-aspirate specimen. M tuberculosis was isolated from the first gastric-aspirate specimen obtained in 16 (72.7%) of 22 cases, whereas in six (27.3%), only the second gastric-aspirate specimen was culture positive (37% greater yield by adding a second specimen). In cases at high risk for tuberculosis, positive results from one or both gastric-aspirate PCRs identified a subgroup with a 50% chance of having a positive culture (13 of 26 cases).

INTERPRETATION

Collection of duplicate gastric-aspirate specimens from high-risk children for MODS culture was the best available diagnostic test for pulmonary tuberculosis. PCR was insufficiently sensitive or specific for routine diagnostic use, but in high-risk children, duplicate gastric-aspirate PCR provided same-day identification of half of all culture-positive cases.

Evaluation of molecular tools for detection and drug susceptibility testing of Mycobacterium tuberculosis in stool specimens from patients with pulmonary tuberculosis

Pulmonary tuberculosis diagnosis is difficult when patients cannot produce sputum. Most sputum is swallowed, and tuberculosis DNA can survive intestinal transit. We therefore evaluated molecular testing of stool specimens for detecting tuberculosis originating from the lungs. Paired stool and sputum samples (n=159) were collected from 89 patients with pulmonary tuberculosis. Control stool samples (n=47) were collected from patients without tuberculosis symptoms. Two techniques for DNA extraction from stool samples were compared, and the diagnostic accuracy of the PCR in stool was compared with the accuracy of sputum testing by PCR, microscopy, and culture. A heminested IS6110-PCR was used for tuberculosis detection, and IS6110-PCR-positive stool samples then underwent rifampin sensitivity testing by universal heteroduplex generator PCR (heteroduplex-PCR) assay. For newly diagnosed pulmonary tuberculosis patients, stool IS6110-PCR had 86% sensitivity and 100% specificity compared with results obtained by sputum culture, and stool PCR had similar sensitivities for HIV-positive and HIV-negative patients (P=0.3). DNA extraction with commercially available spin columns yielded greater stool PCR sensitivity than DNA extraction with the in-house Chelex technique (P=0.007). Stool heteroduplex-PCR had 98% agreement with the sputum culture determinations of rifampin resistance and multidrug resistance. Tuberculosis detection and drug susceptibility testing by stool PCR took 1 to 2 days compared with an average of 9 weeks to obain those results by traditional culture-based testing. Stool PCR was more sensitive than sputum microscopy and remained positive for most patients for more than 1 week of treatment. In conclusion, stool PCR is a sensitive, specific, and rapid technique for the diagnosis and drug susceptibility testing of pulmonary tuberculosis and should be considered when sputum samples are unavailable.

Clinical practice: diagnosis of childhood tuberculosis

Childhood tuberculosis (TB) represents an important part of the disease burden, yet its diagnosis remains challenging. This review summarizes the clinical, radiological, and bacteriological approaches to diagnose TB infection and disease in children. Fever (possibly intermittent or low grade), weight loss or failure to thrive, and a persistent cough for >2 weeks are the most important clinical signs for pulmonary tuberculosis. Extra-pulmonary TB, which might occur in over 40% of the patients, can have in addition some specific clinical symptoms or signs. Chest radiographs provide important information in many patients and advanced imaging can be applied in case of (and should be restricted to) inconclusive diagnosis. The Mantoux test is positive in up to 70% of non-immunocompromised TB patients, whereas HIV co-infection or malnourishment results in a lower reactivity. Evidence of an adult TB index case is clue for diagnosis of childhood TB in low-endemic countries. Bacteriological confirmation remains difficult and is useful for doubtful cases or when drug resistance is suspected.

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

Background and Aim

The diagnosis of pulmonary Tuberculosis (TB) in children is difficult and often requires hospitalization. We explored whether the yield of specimens collected for smear microscopy from different anatomical sites in one visit is comparable to the yield of specimens collected from a single anatomical site over several days.

Methodology and Principal Findings

Children with signs/symptoms of pulmonary TB attending a reference hospital in Sana'a Yemen underwent one nasopharyngeal aspirate (NPA) the first day of consultation and three gastric aspirates (GA) plus three expectorated/induced sputa over 3 consecutive days. Specimens were examined using smear microscopy (Ziehl-Neelsen) and cultured in solid media (Ogawa). Two hundred and thirteen children (aged 2 months–15 years) were enrolled. One hundred and ninety seven (93%) underwent nasopharyngeal aspirates, 196 (92%) GA, 122 (57%) expectorated sputum and 88 induced sputum. A total 1309 specimens were collected requiring 237 hospitalization days. In total, 29 (13.6%) children were confirmed by culture and 18 (8.5%) by smear microscopy. The NPA identified 10 of the 18 smear-positives; three consecutive GA identified 10 and induced/expectorated sputa identified 13 (6 by induced, 8 by expectorated sputum and one positive by both). In comparison, 22 (3.7%) of 602 specimens obtained the first day were smear-positive and identified 14 (6.6%) smear-positive children.

Conclusion/Significance

The examination of multiple tests the first day of consultation identified a similar proportion of smear-positive children than specimens collected over several days; would require half the number of tests and significantly less hospitalization. Optimized smear microscopy approaches for children should be explored further.

Diagnostic and management challenges for childhood tuberculosis in the era of HIV

The diagnosis and management of childhood tuberculosis (TB) pose substantial challenges in the era of the human immunodeficiency virus (HIV) epidemic. The highest TB incidences and HIV infection prevalences are recorded in sub-Saharan Africa, and, as a consequence, children in this region bear the greatest burden of TB/HIV infection. The tuberculin skin test (TST), which is the standard marker of Mycobacterium tuberculosis infection in immunocompetent children, has poor sensitivity when used in HIV-infected children. Novel T cell assays may offer higher sensitivity and specificity than the TST, but these tests still fail to make the crucial distinction between latent M. tuberculosis infection and active disease and are limited by cost considerations. Symptom-based diagnostic approaches are less helpful in HIV-infected children, because of the difficulty of differentiating TB-related symptoms from those caused by other HIV-associated conditions. Knowing the HIV infection status of all children with suspected TB is helpful because it improves clinical management. HIV-infected children are at increased risk of developing active disease after TB exposure/infection, which justifies the use of isoniazid preventive therapy once active TB has been excluded. The higher mortality and relapse rates noted among HIV-infected children with active TB who are receiving standard TB treatment highlight the need for further research to define optimal treatment regimens. HIV-infected children should also receive appropriate supportive care, including cotrimoxazole prophylaxis, and antiretroviral therapy, if indicated. Despite the difficulties experienced in resource-limited countries, the management of children with TB/HIV infection could be vastly improved by better implementation of readily available interventions.

Nasopharyngeal aspiration for diagnosis of pulmonary tuberculosis

BACKGROUND

Confirmation of pulmonary tuberculosis (PTB) in young children is difficult as they seldom expectorate sputum.

AIM

To compare sputa obtained by nasopharyngeal aspiration and by sputum induction for staining and culture of Mycobacterium tuberculosis.

PATIENTS AND METHODS

Patients from Mulago Hospital, Kampala with symptoms suggestive of PTB were considered for inclusion in the study. Those with a positive tuberculin test and/or a chest radiograph compatible with tuberculosis were recruited. Infection with human immunodeficiency virus (HIV) was confirmed by duplicate enzyme-labelled immunosorbent assay or in children <15 months by polymerase chain reaction (PCR). Direct PCR was undertaken on 82 nasopharyngeal aspirates.

RESULTS

Of 438 patients referred, 94 were recruited over a period of 5 months. Median (range) age was 48 (4-144) months. Of 63 patients tested, 69.8% were infected with HIV. Paired and uncontaminated culture results were available for 88 patients and smear results for 94 patients. Nasopharyngeal aspirates were smear-positive in 8.5% and culture-positive in 23.9%. Induced sputa were smear-positive in 9.6% and culture positive in 21.6%. Overall, 10.6% were smear-positive, 25.5% were culture-positive and 26.6% had smear and/or culture confirmed tuberculosis. Direct PCR on nasopharyngeal aspirates had a sensitivity of 62% and specificity of 98% for confirmation of culture-positive tuberculosis.

CONCLUSIONS

Nasopharyngeal aspiration is a useful, safe and low-technology method for confirmation of PTB and, like sputum induction, can be undertaken in outpatient clinics.

Improved recovery of Mycobacterium tuberculosis from children using the microscopic observation drug susceptibility method

OBJECTIVE

The diagnosis of pulmonary tuberculosis presents challenges in children, because symptoms are nonspecific, sputa are not accessible, and Mycobacterium tuberculosis cultures and smears often are negative. The Microscopic Observation Drug Susceptibility technique is a simple, inexpensive method for Mycobacterium tuberculosis isolation with superior speed and sensitivity over Lowenstein-Jensen culture in studies of adults with pulmonary tuberculosis. The objective of this study was to determine whether Microscopic Observation Drug Susceptibility culture can improve the sensitivity and the speed of Mycobacterium tuberculosis recovery among Peruvian children with symptoms suggestive of pulmonary tuberculosis.

METHODS

Two specimens of each type (gastric aspirate, nasopharyngeal aspirate, and stool specimens) were collected from each patient, examined by auramine stain, and cultured by Microscopic Observation Drug Susceptibility and Lowenstein-Jensen techniques. Patients (n = 165) were enrolled between April 2002 and February 2004 at the Instituto de Salud del Niño, the major pediatric hospital in Lima, Peru. Inclusion criteria were age < or = 12 years, Stegen-Toledo clinical score > or = 5 points, and absence of antituberculous therapy. The main outcome measurements were (1) proportion of specimens that were culture positive by Microscopic Observation Drug Susceptibility versus Lowenstein-Jensen and (2) days required for positive culture result, stratified by specimen type and auramine stain result.

RESULTS

Fifteen (9%) patients had at least 1 positive Mycobacterium tuberculosis culture (from stool in 3 cases, nasopharyngeal aspirate in 8 cases, and gastric aspirate in 15 cases). Thirty-eight culture-positive specimens were obtained (22 gastric aspirate, 12 nasopharyngeal aspirates, and 4 stools). Microscopic Observation Drug Susceptibility provided significantly more positive cultures than Lowenstein-Jensen (33 of 38 specimens culture positive by Microscopic Observation Drug Susceptibility vs 21 of 38 by Lowenstein-Jensen). This was attributed to enhanced recovery of Mycobacterium tuberculosis from auramine-negative specimens (19 of 23 by Microscopic Observation Drug Susceptibility vs 9 of 23 by Lowenstein-Jensen), in contrast to similar detection rates for the 2 tests with auramine-positive samples. Similar results were found for analyses that were limited to gastric aspirates. Isolation was faster by Microscopic Observation Drug Susceptibility than Lowenstein-Jensen.

CONCLUSIONS

Isolation of Mycobacterium tuberculosis from children with suspected pulmonary tuberculosis by Microscopic Observation Drug Susceptibility demonstrated greater yield and faster recovery than by Lowenstein-Jensen method, significantly improving local capabilities to detect pediatric tuberculosis in resource-poor settings.

Childhood Pulmonary Tuberculosis

Childhood tuberculosis is neglected in endemic areas with resource constraints, as children are considered to develop mild forms of disease and to contribute little to the maintenance of the tuberculosis epidemic. However, children contribute a significant proportion of the disease burden and suffer severe tuberculosis-related morbidity and mortality, particularly in endemic areas. This review provides an overview of well-documented concepts and principles, and demonstrates how this "old wisdom" applies to current and future challenges in the field of childhood tuberculosis; the aim was to articulate some of the most pressing issues, to provide a rational framework for discussion, and to stimulate thought and further scientific study. The prechemotherapy literature that described the natural history of disease in children identified three central concepts: (1) the need for accurate case definitions, (2) the importance of risk stratification, and (3) the diverse spectrum of disease pathology, which necessitates accurate disease classification. The relevance of these concepts and their application to pertinent issues such as the diagnosis of childhood tuberculosis are discussed. The concepts are also linked to the basic principles of antituberculosis treatment, providing a simplified approach to the diagnosis and treatment of childhood tuberculosis that is independent of resource constraints. The main challenges for future research are highlighted and in conclusion it is emphasized that the infrastructure provided by the directly observed therapy, short-course strategy, combined with well-targeted interventions, slightly improved resources, and greatly improved political commitment, may lead to a dramatic reduction in tuberculosis-related morbidity and mortality among children.

La cuerda dulce--a tolerability and acceptability study of a novel approach to specimen collection for diagnosis of paediatric pulmonary tuberculosis

Background

Recent data demonstrate the utility of the string test for the diagnosis of sputum-scarce HIV-associated TB in adults. We hypothesized that, if well-tolerated by children, this simple tool might offer a breakthrough in paediatric TB diagnosis. Thus the objective of this study, undertaken in the paediatric service of the Hospital Nacional Dos de Mayo, Lima, Perú, was to determine the tolerability and acceptability of the string test to paediatric TB suspects, their parents and nursing staff.

Methods

22 paediatric subjects aged 3–14 years (median 8) under investigation for TB were invited to undergo 2 string tests (four-hour downtime each). Subjective and objective pain and discomfort rating scales were used to assess the perception of the subject, parent and attending nurse.

Results

Patients as young as 4 years tolerated the procedure extremely well with 84% willing to undergo a second procedure. Peak discomfort at the time of swallowing and of string retrieval was mild (30% of maximum possible score) and brief as judged by visual analogue ratings and objective indicators. Good concordance of parent/child and objective/subjective ratings strengthened the validity of these findings.

Conclusion

The string test is well tolerated and achievable for most paediatric TB suspects as young as 4 years. A formal prospective paediatric efficacy study is now needed.

Clinical correlates of tuberculosis co-infection in HIV-infected children hospitalized in Peru

INTRODUCTION

In developing countries, tuberculosis (TB) is responsible for almost 250,000 deaths among children yearly. Active TB in children with human immunodeficiency virus (HIV) infection is difficult to diagnose and progresses rapidly to death. The aim of this preliminary study was to investigate the prevalence and clinical correlates of TB-related illness among HIV-infected children admitted to an infectious diseases ward in Peru, a country where TB is highly endemic.

METHOD

Forty-seven HIV-infected children admitted for a suspected infectious process in a Peruvian hospital were investigated for evidence of clinical tuberculosis by auramine stain, culture, and polymerase chain reaction (PCR) of clinical specimens.

RESULTS

Eight children (17%) had evidence of tuberculosis, including five with positive cultures and three with positive PCR tests only. Weight loss was the only feature associated with a positive test for tuberculosis. Radiological changes were very common in both TB-positive and TB-negative groups and these changes were not useful to identify TB-positive cases.

CONCLUSIONS

Weight loss may be used to identify high-risk HIV positive children who require more aggressive evaluation for tuberculosis. Radiological changes were common in both TB-positive and TB-negative groups.

Childhood tuberculosis in Malawi: caseload, diagnostic practices and treatment outcomes

There were 22,982 cases of TB registered in Malawi in 1998, of which 2739 (11.9%) were children. Children accounted for 11.3% of all case notifications with smear-positive pulmonary TB (PTB), 21.3% with smear-negative PTB and 15.9% with extrapulmonary TB (EPTB). A significantly higher proportion of TB cases were diagnosed in central hospitals. Only 45% of children completed treatment. There were high rates of death (17%), default (13%) and unknown treatment outcomes (21%). Treatment outcomes were worse in younger children and in children with smear-negative PTB. In 2001, all 44 non-private hospitals in Malawi that register and treat children with tuberculosis (TB) were surveyed to determine actual diagnostic practice. This cross sectional study identified 150 children aged 14 years or below in hospital receiving anti-TB treatment, 98 with pulmonary TB (PTB) and 52 with extrapulmonary TB (EPTB). Median duration of illness was 8 weeks. Most patients had fever, no response to anti-malarial treatment and antibiotics, and 40% had a positive family history of TB. Nearly 45% had weight for age < 60%. Diagnosis was mainly based on clinical features and radiography, with less than 10% having tuberculin skin tests or HIV serology, and very few having other sophisticated investigations. Diagnostic difficulties make it difficult to accurately define the actual burden of childhood TB in Malawi. Diagnostic practices are poor and treatment outcomes unsatisfactory.

Tuberkulöse Osteomyelitis des Klivus mit Beteiligung des Nasopharynx

Involvement of the skull base is rare in tuberculosis. We report here the case of a 28-year-old female patient with an osteolytic process of the clivus with compression of the brain stem and involvement of the nasopharynx. She reported suffering from headaches for the last 6 months, and diplopia had occurred 1 week before her diagnosis as a result of paresis of the VIth cranial nerve on the right side. A biopsy was obtained endoscopically via a transnasal approach, revealing a granulomatous inflammation with acid-fast rods and thus confirming the diagnosis of a tuberculoma. When the biopsy was taken there was no evidence of any further tuberculomas in this patient. The clinical picture, diagnosis, and treatment of tuberculosis of the skull base and nasopharynx are discussed and the literature on this rare clinical entity is reviewed with reference to this patient's case report.

Perinatal tuberculosis and HIV-1: considerations for resource-limited settings

Tuberculosis is the commonest HIV-1-related disease and the most frequent cause of mortality in young women in endemic regions. Tuberculosis and HIV-1 are independent risk factors for maternal mortality and adverse perinatal outcomes, and in combination have a greater impact on these parameters than their individual effects. In referral health centres in southern Africa around one-sixth of all maternal deaths are due to tuberculosis/HIV-1 coinfection. One-third (37%) of HIV-1-infected mothers with tuberculosis are severely immunocompromised, with CD4 counts of fewer than 200 cells/microL compared with 14-19% in mothers recruited into major mother-to-child intervention trials in Europe. Babies born to mothers with tuberculosis/HIV-1 also have higher rates of prematurity, low birthweight, and intrauterine growth restriction. Transmission rates of HIV-1 from mother to infant are around 25-45% in resource-limited settings, while that for mother-to-child-transmission of tuberculosis is 15% within 3 weeks of birth. We highlight this emergent problem, and discuss the dilemmas associated with diagnosis and management of pregnant HIV-1-infected mothers with tuberculosis, and their newborn babies.

Evaluation of a PCR-based universal heteroduplex generator assay as a tool for rapid detection of multidrug-resistant Mycobacterium tuberculosis in Peru

Multidrug-resistant tuberculosis is an increasing health problem worldwide, especially in developing countries. The PCR-UHG-Rif assay, which detects mutations within the rpoB gene associated with rifampin resistance, was evaluated for its ability and reliability to detect and identify drug-resistant Mycobacterium tuberculosis in a developing country where tuberculosis is highly endemic.

Improved detection of Mycobacterium tuberculosis in Peruvian children by use of a heminested IS6110 polymerase chain reaction assay

A novel heminested IS6110 polymerase chain reaction (PCR) assay was evaluated as a tool for diagnosing tuberculosis in 222 children. In an analysis of 392 specimens (gastric aspirates, nasopharyngeal aspirates, and sputum samples), results of PCR were compared with those of 3 culture methods, acid-fast bacillus (AFB) staining, and clinical assessment by the Stegen-Toledo score. The sensitivity of PCR (67%) was comparable to that of the 3-culture method (71%) and was significantly higher than that of Löwenstein-Jensen culture (54%) or AFB stain (42%) for children with highly probable tuberculosis. PCR detection rates for culture-positive specimens were 100% for smear-positive samples and 76.7% for smear-negative samples. The specificity of PCR was 100% in control children. Compared with culture, PCR demonstrated a sensitivity of 90.4%, a positive predictive value of 89%, a specificity of 94%, and a negative predictive value of 95% (kappa=.85). With clinical assessment as the standard, PCR had a sensitivity of 71%, a positive predictive value of 92%, a specificity of 95%, and a negative predictive value of 79% (kappa=.67). PCR is a rapid and sensitive method for the early diagnosis of pediatric tuberculosis.

Tuberculosis in children-is PCR the diagnostic solution?

Polymerase chain reaction (PCR) has been recently incorporated as a diagnostic tool for the diagnosis of tuberculosis. The benefit of rapid results and greater sensitivity compared with traditional microbiological methods makes PCR a suitable technique in childhood tuberculosis, especially when diagnosis is difficult or when urgent diagnosis is needed. However, the possibility of false-positive results must be considered, especially if the clinical and epidemiologic context of the child make the diagnosis of tuberculosis improbable. The commercial 'Amplicor PCR test' lacks good sensitivity and specificity and it would be necessary to develop other commercial easy-to-use PCR kits that provides better yield.

Pulmonary tuberculosis in children in a developing country

OBJECTIVE

We evaluated the clinical and epidemiologic characteristics of Peruvian children presenting with pulmonary tuberculosis (PTB) to determine whether features predictive of confirmed PTB could be identified.

STUDY DESIGN

This was a cross-sectional study of 135 children (mean age: 6.8 years) presenting to the Hospital del Niño in Lima, Peru, with presumptive diagnosis of PTB. Clinical, epidemiologic, and laboratory findings were compared between 3 groups of pediatric patients with a presumptive diagnosis of PTB: those with positive Mycobacterium tuberculosis (MTB) cultures, those likely to have PTB based on clinical criteria but with negative cultures, and those who did not meet clinical diagnostic criteria or have positive cultures.

RESULTS

A total of 50 (37%) patients were diagnosed with definitive PTB based on positive sputum culture. Another 55 (47%) patients were classified as having probable PTB based on meeting at least 2 of the following criteria: cough lasting for at least 2 weeks, typical chest radiograph changes, purified protein derivative (PPD) >/=10 mm, or history of tuberculosis family contact. Patients with definitive or probable PTB were significantly older than patients without clinical PTB, and those with symptomatic disease were significantly older than those with asymptomatic disease. Patients with PTB diagnosed by culture were significantly more likely than those diagnosed using clinical criteria to have cough lasting >/=2 weeks, fever, and a PPD >/=10 mm.

CONCLUSIONS

The typical presentation of PTB in Peruvian children includes symptoms of active pulmonary disease similar to those seen in adults. This presentation differs significantly from that reported in developed countries, where many children have minimal or no symptoms at the time of presentation. The diagnostic criteria for pediatric PTB must be modified in hyperendemic developing country environments where features may differ from those described in the United States. The triad of cough lasting >/=2 weeks, fever, and a PPD >/=10 mm was highly predictive for culture-positive PTB among children in this low-income Peruvian population.

Current issues in maternal and perinatal tuberculosis: impact of the HIV-1 epidemic

Human immunodeficiency virus type 1 (HIV-1) and tuberculosis (TB) are among the leading causes of disability and death in the developing world, the largest burden borne by sub-Saharan Africa and Asia. Both diseases are significant among women of childbearing age, and TB, although uncommon in pregnancy, is on the increase. While earlier reports were contradictory regarding the effect of TB on the course of pregnancy and vice versa, the negative impacts of each on the other have been documented, some in relation to HIV-1 co-infection. This review focuses on emerging data on maternal and perinatal TB within the context of HIV-1 infection.

Childhood tuberculosis

Childhood tuberculosis will reflect the incidence of cavitating pulmonary tuberculosis in adults and will consequently be encountered most frequently in those areas with a high incidence of tuberculosis. Problem areas include our continuing inability to confirm the diagnosis of tuberculosis in many children, the escalating interaction of the human immunodeficiency virus (HIV) pandemic and tuberculosis, which is now evident with greater frequency in childhood, and the scarcity of data relating to antituberculosis therapy in childhood, which necessitates reliance on adult studies in many cases. This review highlights several options for obtaining material for culture of Mycobacterium tuberculosis in children, aspects of tuberculin testing, which remains one of the cornerstones supporting a diagnosis of tuberculosis in childhood, the potential importance of therapeutic drug monitoring in problem cases, new data giving epidemiologic and clinical details of the interaction of HIV infection and tuberculosis in children, and studies describing the epidemiology of tuberculosis in the developed and developing world.

Laryngeal swabs for diagnosing tuberculosis

The value of smear and culture of laryngeal swabs as a method of confirming pulmonary tuberculosis was investigated in Indian children. A total of 116 children with 'suspected' tuberculosis had a Mantoux test and chest X-ray. Of these, 51 had a positive Mantoux and/or chest X-ray compatible with tuberculosis, and this group had two laryngeal swabs taken on each of 3 consecutive days. The Mantoux test was positive in 37 (73%) of the 51 'probable' cases. Chest X-ray was abnormal in 36 (71%) cases and compatible with tuberculosis in 20 (39.7%). Mycobacterium tuberculosis was cultured from laryngeal swabs in 14 (28%) children and in another three children smears were positive but culture-negative. The overall confirmation rate for tuberculosis was 33%. Laryngeal swabs are a simple method of confirming tuberculosis and may be undertaken in out-patients.