Detection of Mycobacterium tuberculosis in gastric aspirates collected from children: hospitalization is not necessary

Evaluation of GeneXpert and liquid culture for detection of Mycobacterium tuberculosis in pediatric patients

PURPOSE

Evaluation of GeneXpert in comparison to liquid culture using Mycobacteria Growth Indicator Tube (MGIT) as gold standard for detection of Mycobacterium tuberculosis (MTB) in children.

METHODS

A total of 8123 samples, both pulmonary (5830) and extra pulmonary (2293) received from pediatric patients were processed for Acid Fast Bacilli (AFB) smear, GeneXpert and MGIT culture simultaneously.

RESULTS

Out of 8123 samples, 493 (6.1%) samples were found positive by GeneXpert and 508 (6.2%) samples by MGIT culture, 371 (4.6%) were found positive by both GeneXpert and MGIT culture. MGIT detected 137 (1.7%) extra positive than GeneXpert while GeneXpert detected 122 (1.5%) extra samples more positive than by MGIT. Sensitivity of GeneXpert was 73% and concordance between both methods was 96.8%. Rifampicin resistance was found in 49 (9.9%) samples among MTB positive by GeneXpert. Turnaround time for GeneXpert was approx. 2 ​h and for MGIT, it was 12-28 days.

CONCLUSION

Good sensitivity (73%) and concordance (96.8%) were observed for GeneXpert against MGIT culture in this study. GeneXpert can simultaneously detect MTB and rifampicin resistance in less than 2 ​h while MGIT takes 12-28 days for MTB detection only.

Nanofiber capsules for minimally invasive sampling of biological specimens from gastrointestinal tract

Accurate and rapid point-of-care tissue and microbiome sampling is critical for early detection of cancers and infectious diseases and often result in effective early intervention and prevention of disease spread. In particular, the low prevalence of Barrett's and gastric premalignancy in the Western world makes population-based endoscopic screening unfeasible and cost-ineffective. Herein, we report a method that may be useful for prescreening the general population in a minimally invasive way using a swallowable, re-expandable, ultra-absorbable, and retrievable nanofiber cuboid and sphere produced by electrospinning, gas-foaming, coating, and crosslinking. The water absorption capacity of the cuboid- and sphere-shaped nanofiber objects is shown ∼6000% and ∼2000% of their dry mass. In contrast, unexpanded semicircular and square nanofiber membranes showed <500% of their dry mass. Moreover, the swallowable sphere and cuboid were able to collect and release more bacteria, viruses, and cells/tissues from solutions as compared with unexpanded scaffolds. In addition to that, an expanded sphere shows higher cell collection capacity from the esophagus inner wall as compared with the unexpanded nanofiber membrane. Taken together, the nanofiber capsules developed in this study could provide a minimally invasive method of collecting biological samples from the duodenal, gastric, esophagus, and oropharyngeal sites, potentially leading to timely and accurate diagnosis of many diseases. STATEMENT OF SIGNIFICANCE: Recently, minimally invasive technologies have gained much attention in tissue engineering and disease diagnosis. In this study, we engineered a swallowable and retrievable electrospun nanofiber capsule serving as collection device to collect specimens from internal organs in a minimally invasive manner. The sample collection device could be an alternative endoscopy to collect the samples from internal organs like jejunum, stomach, esophagus, and oropharynx without any sedation. The newly engineered nanofiber capsule could be used to collect, bacteria, virus, fluids, and cells from the abovementioned internal organs. In addition, the biocompatible and biodegradable nanofiber capsule on a string could exhibit a great sample collection capacity for the primary screening of Barret Esophagus, acid reflux, SARS-COVID-19, Helicobacter pylori, and gastric cancer.

Diagnostic Advances in Childhood Tuberculosis—Improving Specimen Collection and Yield of Microbiological Diagnosis for Intrathoracic Tuberculosis

There is no microbiological gold standard for childhood tuberculosis (TB) diagnosis. The paucibacillary nature of the disease, challenges in sample collection in young children, and the limitations of currently available microbiological tests restrict microbiological confirmation of intrathoracic TB to the minority of children. Recent WHO guidelines recommend the use of novel rapid molecular assays as initial diagnostic tests for TB and endorse alternative sample collection methods for children. However, the uptake of these tools in high-endemic settings remains low. In this review, we appraise historic and new microbiological tests and sample collection techniques that can be used for the diagnosis of intrathoracic TB in children. We explore challenges and possible ways to improve diagnostic yield despite limitations, and identify research gaps to address in order to improve the microbiological diagnosis of intrathoracic TB in children.

Diagnostic Accuracy of Loop-Mediated Isothermal Amplification (TB-LAMP) for Tuberculosis in Children

BACKGROUND

Diagnosing tuberculosis (TB) in children is challenging due to its paucibacillary nature. Loop-mediated isothermal amplification (TB-LAMP) is a simple, rapid, and specific point-of-care molecular diagnostic test. However, evaluation of its performance remains limited in children. This study aimed to evaluate the diagnostic performance of Eiken TB-LAMP among children with presumed tuberculosis disease.

METHODS

Pulmonary and extrapulmonary specimens were collected from children under 18 years with presumed TB. Each specimen was tested by using TB-LAMP, acid-fast bacilli (AFB) smear microscopy, and one of the two molecular assays (polymerase chain reaction [PCR] or Xpert MTB/RIF). Sensitivity and specificity were estimated compared to mycobacterial culture as reference standard.

RESULTS

From January 2020 to January 2021, 75 participants with presumed TB were enrolled with median age of 7 years (IQR 2-12). Seventeen specimens from 16 (21.3%) children had bacteriologically confirmed TB: 10 pulmonary and 7 extrapulmonary specimens. Overall sensitivity and specificity of TB-LAMP was 76.5% (95% CI 50.1%-93.2%) and 100% (95% CI 94.3%-100%), respectively. It had significantly higher sensitivity than AFB (52.9%, 95% CI 27.8%-77.0%) and similar to other molecular assays; PCR 82.4% (95% CI 56.6%-96.2%), Xpert MTB/RIF 70.0% (95% CI 34.8%-93.3%). Sensitivity of TB-LAMP for pulmonary, lymph node tissue, and extrapulmonary fluid was 80% (95% CI 44.4%-97.5%), 100% (95% CI 39.8-100), and 33.3% (95% CI 0.8-90.6), respectively. TB-LAMP detected all smear-positive (N = 9) and 50% of smear-negative (N = 8) specimens.

CONCLUSIONS

TB-LAMP had higher sensitivity than AFB microscopy and accuracy similar to other molecular assays in both pulmonary and extrapulmonary specimens. These findings support using TB-LAMP as a point-of-care test in children.

Strengthening Tuberculosis Services for Children and Adolescents in Low Endemic Settings

In low tuberculosis-burden countries, children and adolescents with the highest incidence of tuberculosis (TB) infection or disease are usually those who have immigrated from high-burden countries. It is, therefore, essential that low-burden countries provide healthcare services to immigrant and refugee families, to assure that their children can receive proper testing, evaluation, and treatment for TB. Active case-finding through contact tracing is a critical element of TB prevention in children and in finding TB disease at an early, easily treated stage. Passive case-finding by evaluating an ill child is often delayed, as other, more common infections and conditions are suspected initially. While high-quality laboratory services to detect Mycobacterium tuberculosis are generally available, they are often underutilized in the diagnosis of childhood TB, further delaying diagnosis in some cases. Performing research on TB disease is difficult because of the low number of cases that are spread over many locales, but critical research on the evaluation and treatment of TB infection has been an important legacy of low-burden countries. The continued education of medical providers and the involvement of educational, professional, and non-governmental organizations is a key element of maintaining awareness of the presence of TB. This article provides the perspective from North America and Western Europe but is relevant to many low-endemic settings. TB in children and adolescents will persist in low-burden countries as long as it persists throughout the rest of the world, and these wealthy countries must increase their financial commitment to end TB everywhere.

Discordance between TST and QFT-TBGold Plus for Latent Tuberculosis Screening among Under-Five Children: An Interim Analysis

AIM

To analyze the agreement between tuberculin skin test (TST) and fourth-generation QuantiFERON (QFT)-TB Gold Plus [interferon gamma (INF-γ) release assays (IGRA)] for latent tuberculosis infection (LTBI) diagnosis among under-five children who are undernourished and/or who have history of contact with active tuberculosis (TB) patients.

METHODS

Children from the age group of 6 months to 5 years (undernourished or tuberculosis household contacts) were screened through anganwadis (government playschools) and TB Health posts from Mumbai, India during September 2019 to January 2021. Both TST and QFT-TB Gold Plus test were carried out to diagnose LTBI.

RESULTS

Out of the total 299, 35 (11.7%) (95% CI 8.1-15.3%) children tested positive by IGRA (QFT-TB Gold Plus) and 68 (22.7%) (95% CI 18.0-27.4%) by TST, suggestive of moderate concordance (κ = 0.483) between both tests. IGRA and TST showed moderate concordance in children <24 months (κ = 0.478). Moreover, 26 (21.1%) children with TB contact had both TST and IGRA positive with moderate concordance (κ = 0.550). A fair concordance (κ = 0.396) was observed between IGRA and TST in undernourished children. Also, 45 (15.0%) children showed discordance of which 39 (13.0%) had positive TST but negative IGRA and 6 (2.0%) had negative TST but positive IGRA.

CONCLUSIONS

The study strongly recommends both TST and QFT-TB Gold Plus test for the diagnosis of LTBI in under-five children. A moderate concordance in children <24 months endorses the reliability of QFT-TB Gold Plus in diagnosing LTBI in this age group. This study highlights the need for screening undernourished children for LTBI to consider repeating IGRA testing for TST positives as per the window period and risk of ongoing exposure.

Diagnostic Validity of Gastric Aspirate Culture in Nontuberculous Mycobacterial Pulmonary Disease

Rationale: Although gastric aspirate culture is used for diagnosing pulmonary tuberculosis, its usefulness in diagnosing pulmonary infections of nontuberculous mycobacteria (NTM) is unknown.Objectives: To investigate the diagnostic validity of gastric aspirate culture for acid-fast bacilli in NTM pulmonary disease (NTM-PD).Methods: Gastric aspirates were collected from patients with suspected NTM-PD at the Osaka Toneyama Medical Center between December 2006 and February 2018. Patients with a final diagnosis of pulmonary tuberculosis, an observation period of less than 6 months, or fewer than three conducted sputum cultures were excluded from the study. NTM-PD was diagnosed as per American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) criteria. We retrospectively examined the diagnostic validity of gastric aspirate culture in Mycobacterium avium complex (MAC)-PD and M. kansasii-PD by comparing culture results with final diagnoses. This was done first for all patients, and subsequently for patients with negative results for early sputum cultures. In addition, we compared the time required for an NTM-PD diagnosis based on gastric aspiration with that based on ATS/IDSA criteria.Results: Among 475 total patients, 119 (25.1%) had positive NTM gastric aspirate cultures and 154 (32.4%) fulfilled the ATS/IDSA criteria for NTM-PD. The sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPVs) of gastric aspiration were 63.9%, 95.8%, 83.5%, and 88.8% in MAC-PD and 82.4%, 99.6%, 87.5%, and 99.3% in M. kansasii-PD, respectively. Sensitivity, specificity, PPV, and NPV of gastric aspirate cultures of the 378 patients who were undiagnosed based on sputum culture within 120 days were 34.0%, 95.5%, 51.6%, and 91.1% for MAC-PD and 75.0%, 99.5%, 60.0%, and 99.7% for M. kansasii-PD, respectively. Furthermore, gastric aspirate cultures tested in addition to bronchoscopy yielded incremental sensitivity of 8.7% (95.7% vs. 87.0%) and an NPV of 1.3% (99.3% vs. 98.0%) in MAC-PD. In patients with NTM-PD with NTM-positive gastric aspirate cultures, the period between gastric aspirate collection and the positive culture result was shorter than the time between gastric aspirate collection and NTM-PD diagnosis (6 [9-36] d vs. 25 [12-69] d, median [interquartile range], P < 0.0001].Conclusions: In settings where acid-fast bacilli pulmonary diseases are suspected, gastric aspirate culture may be helpful for diagnosing MAC-PD and M. kansasii-PD.

Evaluation of Xpert MTB/RIF Ultra Assay for Diagnosis of Childhood Tuberculosis: a Multicenter Accuracy Study

A multicenter study was performed to evaluate the value of testing gastric aspirate (GA) with Xpert MTB/RIF Ultra assay (Ultra) for childhood tuberculosis (TB) detection in China. In total, 129 children with active TB and 173 children without TB were enrolled. The sensitivity of Ultra in bacteriologically confirmed TB and probable TB cases was 87.5% (42/48) and 44.4% (36/81), respectively. The specificity of Ultra was high (99.4%, 172/173). When Ultra, culture, and acid-fast bacilli outcomes were integrated as a composite reference standard, the percentage of children with definite TB increased from 37.

A multicenter study was performed to evaluate the value of testing gastric aspirate (GA) with Xpert MTB/RIF Ultra assay (Ultra) for childhood tuberculosis (TB) detection in China. In total, 129 children with active TB and 173 children without TB were enrolled. The sensitivity of Ultra in bacteriologically confirmed TB and probable TB cases was 87.5% (42/48) and 44.4% (36/81), respectively. The specificity of Ultra was high (99.4%, 172/173). When Ultra, culture, and acid-fast bacilli outcomes were integrated as a composite reference standard, the percentage of children with definite TB increased from 37.2% (48/129) to 67.4% (87/129). The sensitivity of Ultra is 80.0% (40/50) in children aged <4 years, which is significantly higher than that in older children (48.1%, 38/79) (P < 0.001). Ultra conducted using GA samples can provide faster results, allowing an early and accurate TB diagnosis, especially in younger children with difficulty producing sputum.

Combined Use of Gastric Aspirate and Induced Sputum Increases the Microbiological Diagnosis of Tuberculosis in Children

Objective Diagnosis of pulmonary tuberculosis (PTB) in pediatrics is a challenge due to the paucibacillary condition of the disease in this population, low sputum expectoration, and diverse unspecific symptomatology. Mycobacterial isolation through culture remains a priority. The objective of this study is to explore gastric aspirates and induced sputum techniques in the pediatric population for positivity on mycobacterial cultures.

Methods In this observational analytical study, two temporal groups were evaluated. A comparison of the isolation rate defined as positive culture confirmation by gastric aspirate (GA), induced sputum (IS), or combination of these both techniques in children under 10 years of age. The study included 86 children, 37 in the first evaluated study group and 49 in the second group.

Discussion Culture positivity was 10.8 and 30.6% for the first and second case series, respectively. These findings showed that the combination of GA and IS in two consecutive days yielded a significantly higher detection rate to confirm pulmonary tuberculosis by culture.

Conclusion The combination of GA plus IS samples for collection of M. tuberculosis culture can be a useful, nonexpensive, and safe diagnostic tool in low- and middleincome countries to diagnose tuberculosis in children.

Gastric specimens for diagnosing tuberculosis in adults unable to expectorate in Rawalpindi, Pakistan

Setting: Adult pulmonary tuberculosis (TB) patients unable to expectorate quality sputum represent a diagnostic challenge. A private hospital in Pakistan routinely performs gastric aspiration in adults with difficulties expectorating. Objective: To assess the usefulness of gastric specimens (GS) in diagnosing pulmonary TB (PTB) and drug-resistant TB in adult presumptive TB patients unable to expectorate, and to compare the diagnostic yield and sensitivity of smear, culture and the Xpert^® MTB/RIF assay. Design: This was a comparative cross-sectional study based on retrospective record review. Results: Of 900, 885 and 877 GS tested by smear, Xpert and culture, respectively, interpretable results were obtained for respectively 900 (100%), 859 (97.1%) and 754 (86.0%), with a diagnostic yield of respectively 23.6%, 30.3% and 24.9%. The yield was significantly higher for Xpert in previously treated patients. There were 313 patients with definite TB, defined as positive on Xpert and/or culture. The 82.8% sensitivity of Xpert was significantly higher than that of smear (61.0%) and culture (67.8%). Conclusion: GS obtained by aspiration under routine programme conditions is useful for detecting TB and drug-resistant TB in adult patients unable to expectorate. Xpert, with its rapid testing, high proportion of interpretable results and better sensitivity, can substantially improve the diagnosis of bacteriologically confirmed TB and rifampicin resistance.

Nontuberculous mycobacteria in gastrostomy fed patients with cystic fibrosis

Multi-drug resistant Mycobacterium abscessus complex (MABSC) is a form of Nontuberculous mycobacteria (NTM) of special, international concern in Cystic Fibrosis (CF). We hypothesised that gastric juice and percutaneous endoscopic gastrostomy (PEG) feeding devices might yield MABSC isolates. Gastric juice and sputa from sixteen adult PEG fed CF patients and five replaced PEG tubes were studied. Bacterial and fungal isolates were cultured. Mycobacterium were identified by rpoB, sodA and hsp65 gene sequencing and strain typed using variable number tandem repeat. Bacteria and/or fungi grew from all gastric juice, sputa and PEG samples. MABSC were detected in 7 patients. Five had MABSC in their sputum. Two had an identical MABSC strain in their sputum and gastric juice and one had the same strain isolated from their PEG tube and sputum. Two patients who were sputum sample negative had MABSC isolated in their gastric juice or PEG tube. MABSC were therefore identified for the first time from a gastric sample in a minority of patients. We conclude that gastric juice and PEG-tubes may be a potential source of MABSC isolates in CF patients, and these findings warrant further study.

Epidemiology and clinical management of tuberculosis in children in Canada

Although often regarded as a foreign disease, latent tuberculosis or tuberculosis disease will be encountered in many clinical situations by the Canadian child health practitioner. There are key differences between tuberculosis in children and adults. In the present article, the changing epidemiology of tuberculosis in children in Canada and around the world, the pathogenesis of infection, diagnostic tests, and clinical management of childhood latent tuberculosis and tuberculosis disease are reviewed.

Utility of gastric aspirates for diagnosing tuberculosis in children in a low prevalence area: predictors of positive cultures and significance of non-tuberculous mycobacteria

BACKGROUND

In countries with low rates of tuberculosis (TB), yields of gastric aspirates (GAs) for Mycobacterium tuberculosis (MTB) culture are low. The significance of non-tuberculous mycobacteria (NTM) isolated from GA is uncertain.

METHODS

We reviewed clinical, microbiologic and radiologic data for children who underwent GA between 1999 and 2011 at Sick Kids, Toronto. Radiologic features of cases were compared with those of age matched controls.

RESULTS

785 GAs were obtained from 285 patients of whom 20 (7%) had positive MTB cultures: in 15 patients the GA was the only positive culture for MTB. Of 15 culture-positive patients who underwent exactly 3 GAs, MTB was isolated from the first lavage in 10 (67%), only from the second in 3 (20%) and only from the third in 2 (13%). On univariate analysis, miliary disease and intrathoracic lymphadenopathy were associated with a positive GA MTB culture. On multiple conditional logistic regression analysis, adenopathy remained significant (OR 10.2 [95% CI 2.0-51.4] p =0.005). Twelve patients had NTM isolated, most commonly M. avium complex: none had evidence of invasive NTM disease during a median duration of 12 months of follow-up. Causal pathogens different from the GA NTM culture were isolated from biopsies or bronchoalveolar lavage in 3.

CONCLUSIONS

GAs continue to be important for TB diagnosis in children. Three GAs have a yield better than 1. Those with miliary or disseminated TB and intrathoracic lymphadenopathy have highest yields. NTM isolates from GA are likely unimportant and can be clinically misleading.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Genotype diversity of Mycobacterium isolates from children in Jimma, Ethiopia

BACKGROUND

Paediatric tuberculosis (TB) is poorly addressed in Ethiopia and information about its magnitude and the genotype distribution of the causative Mycobacterium tuberculosis strains responsible for its spread are scanty.

METHODS

Gastric lavage or sputum samples were collected from consecutively enrolled TB suspect children visiting Jimma University Hospital in 2011 and cultured on Middlebrook 7H11 and Löwenstein-Jensen media. Acid fast bacterial (AFB) isolates were subjected to molecular typing targeting regions of difference (RDs), 16S rDNA gene and the direct repeat (DR) region using multiplex polymerase chain reaction (mPCR), gene sequencing and spoligotyping, respectively. Molecular drug susceptibility testing of M. tuberculosis isolates was performed by Genotype®MTBDRplus line probe assay (LPA) (Hain Life Sciences, Germany).

RESULTS

Gastric lavage (n = 43) or sputum (n = 58) samples were collected from 101 children and 31.7% (32/101) of the samples were positive for AFB by microscopy, culture and/or PCR. Out of 25 AFB isolates, 60% (15/25) were identified as M. tuberculosis by PCR, and 40% isolates (10/25) were confirmed to be non-tuberculous mycobacteria (NTM) by genus typing and 16S rDNA gene sequencing. Lineage classification assigned the M. tuberculosis strains into Euro-American (EUA, 66.7%; 10/15), East-African-Indian (EAI; 2/15), East-Asian (EA; 1/15) and Indio-Oceanic (IO; 1/15) lineages. Seven M. tuberculosis strains were new to the SpolDB4 database. All of the M. tuberculosis isolates were susceptible to isoniazid (INH) and rifampicin (RIF), except for one strain (of spoligotype SIT-149 or T3_ETH family) which had a mutation at the inhA locus which often confers resistance to INH (low level) and ethionamide.

CONCLUSIONS

Analysis of the genetic population structure of paediatric M. tuberculosis strains suggested similarity with that of adults, indicating an on-going and active transmission of M. tuberculosis from adults to children in Ethiopia. There were no multidrug-resistant TB (MDR-TB) strains among the isolates.

Gastric Aspirate Yield For Children With Suspected Pulmonary Tuberculosis

The optimal number of gastric aspirates to diagnose tuberculosis is unclear. Thirty-two of 280 (11%) children in whom gastric aspirates were obtained grew Mycobacterium tuberculosis. First, second, and third specimens yielded initial culture positivity in 24 of 32, 6 of 32, and 2 of 24 cases, respectively. Intermittent positivity and paucibacillary disease necessitate obtaining multiple specimens.

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.

"Induced sputum versus gastric lavage for the diagnosis of pulmonary tuberculosis in children"

Background

Diagnosis of pulmonary tuberculosis (PTB) is difficult in infants and young children. For microbiological confirmation of PTB children, sequential gastric lavage (GL) is recommended. Induced sputum (IS) may be an alternative or complementary tool, but the information is limited in children in developed countries. The aim of this study is to assess the safety and diagnostic yield from IS combined with GL for PTB diagnosis in non-HIV infected children.

Methods

The study involved 22 children with suspected PTB admitted to the Getafe Hospital from January 2007 to May 2011. IS and GL were performed on three consecutive days, according to a standardized protocol. In all samples, BK staining, culture and PCR were carried out, including Genotype MTBDR plus for resistance to INH-RIF (Isoniazid-Rifampin) since 2008. A preliminary analysis of an ongoing prospective study is presented.

Results

Median age was 72 months (range 1 month to 14 years of age). Seven (33%) were ≤ 5 years of age. Seventeen were clinically diagnosed of PTB based on positive PPD and radiological criteria. Microbiological confirmation was achieved in 10 (58.8%) by either GL or IS. M. tuberculosis was identified by GL in 8 children (47.1%) and by IS in 7 (41.2%). One infant (2 IS samples) had transient oxygen desaturation recovered spontaneously.

Conclusions

IS appears to be safe and well tolerated by children for diagnosis of PTB and is more convenient. Increasing the diagnostic yield of PTB in children with PTB may be a complementary technique. Largest studies are necessary to define the role of IS in paediatric PTB.

Usefulness of thoracic CT to diagnose tuberculosis disease in patients younger than 4 years of age

BACKGROUND

There is controversy over the need of using thoracic CT (TCT) systematically for differentiating disease from tuberculosis infection in young children. This distinction is important when making a diagnosis of TB as the treatment changes from a single drug to a multidurug regimen with reported side-effects.

AIM

To determine the usefulness of using TCT to diagnose pulmonary tuberculosis (PTB) in patients younger than 4 years of age who have TB infection (IBI).

MATERIALS AND METHODS

After the simultaneous detection of four cases of PTB in children who attended the same class, a study on the contact among workers and children was carried out. One hundred sixteen children younger than 4 years and 20 adults were included. The tuberculin skin test (TST) was performed on all of them. CHEST XR (CXR) and TCT were performed on children with positive TST and three samples of gastric acid were taken. CXR and sputum testing were performed on adults with positive TST.

RESULTS

TST was positive in 28 children (24.1%). In 92.8% of children with positive TST and normal CXR, TCT showed features compatible with PTB. Out of the 28 children with positive TST, 27 (96.4%) were diagnosed with PTB and only one with latent TBI (4%).

CONCLUSIONS

In children younger than 4-year old with positive TST and normal CXR, it would be advisable to perform a TCT since the findings could change the diagnosis from TBI to TB disease.

A prospective assessment of the role of bronchoscopy and bronchoalveolar lavage in evaluation of children with pulmonary tuberculosis

OBJECTIVE

To assess the diagnostic yield of fibreoptic bronchoscopy and bronchoalveolar lavage (BAL) compared to gastric aspiration (GA) in children with probable pulmonary tuberculosis (TB).

METHODS

Children with probable pulmonary TB were subjected to bronchoscopy, BAL and gastric aspiration. The samples were examined for acid fast bacilli (AFB) on smear.

RESULTS

A total of 52 children underwent bronchoscopy with BAL and GA. AFB on smear was identified in 19 (36.5%); BAL was positive in 16 (30.8%) and GA was positive in 11 (21.15%). GA alone was positive in 3 (5.67%) while BAL alone was positive in 8 (15.38%). Bronchoscopy detected airways' abnormality in 29 (56%) of patients. One GA and BAL detected AFB in majority of patients.

CONCLUSION

The diagnostic yield for AFB from BAL was better than that from GA in children with probable pulmonary TB. Combining one GA and bronchoscopy may improve AFB yield in children with pulmonary TB.

[Specific features of tuberculosis in childhood]

Primary infection with Mycobacterium tuberculosis usually occurs during childhood. The source of infection is most often an adult. The risk of infection in exposed children is modulated by various factors related to the infectiousness of the index case, exposure conditions, and the child himself. This review aims to describe the specific diagnostic and therapeutic features of latent TB infection and TB disease in childhood.

[Tuberculosis outbreak in a primary school: description and reflections on the value of gastric juice in the management of micro-epidemics]

AIMS

To describe a tuberculosis outbreak in a primary school arising from a secondary case.

METHODS

Contact study and clinical study of exposed patients. Chest x-ray, gastric aspirate processing, and clinical evaluation of all children with a positive tuberculin skin test (TST) were recorded. Differential diagnosis between tuberculosis disease (TB) and latent tuberculosis infection (LTI).

RESULTS

Two groups were identified: one of higher exposure to the index case (> 6 hours/day, for 3 months; n=17 children) and one of sporadic exposure (< 6 hours/day; n=82 children). Clinical or bacteriological criteria for diagnosing TB were seen in 6 out of 17 (35%) highly exposed children. Four of them had clinical or radiological criteria. The other two children were asymptomatic and had a normal chest X ray, but had a positive gastric aspirate for M. tuberculosis. The overall infection rate (TB+LTI) was 94%. One child out of 82 (1.2%) sporadically exposed children had radiological criteria for TB. Staff latent infection rate was 15%. Apart from the index case, there were no other tuberculosis cases among the staff. Relative risk (RR) of exposed children was 28.5 (95% CI: 3-250).

CONCLUSIONS

Prolonged exposure to a baciliferous patient may infect almost every child exposed in closed groups. It can also cause a high attack rate. In this scenario, routine gastric aspirate may be considered for all children with a positive TST. It may identify early subclinical TB with an increased probability of isolating the M. tuberculosis. The potential benefit of this isolation may reach the entire cohort.

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.

Impact of immigration on pulmonary tuberculosis in Spanish children: a three-decade review

BACKGROUND

Tuberculosis causes significant morbidity and mortality worldwide. In the last years, international travel and immigration have led to important changes in the epidemiology of this disease. Drug resistance has emerged as an important threat to tuberculosis control. Data regarding the impact of immigration and the incidence of drug-resistant strains in children are lacking.

METHODS

Retrospective review of patients diagnosed with pulmonary tuberculosis at La Paz Children's Hospital in a 30-year period. Data were collected with regard to the clinical, radiologic, microbiologic, and demographic characteristics of patients, and data from the 3 decades of the study were compared using chi test and Fisher exact test.

RESULTS

A total of 507 cases of tuberculosis were identified, 414 of which had pulmonary involvement. During the study, there was a significant decrease in tuberculous meningitis: 10.4% in 1978-1987, 5.6% in 1988-1997, and 2.9% in 1998-2007 (P < 0.05). The most frequent reason for a consultation was case contact investigation. The adult source case was identified in 64% of patients. We observed an increase in extrafamilial contacts (8% in 1978-1987 and 18% in 1998-2007, P < 0.01), including 4 cases of immigrant caretakers. Tuberculosis in immigrant children has increased with time: 2% in the period 1978-1987, 6% in 1988-1997, and 46% in 1998-2007 (P < 0.001). The primary resistance rate to isoniazid in our population was 6.5%.

CONCLUSIONS

Tuberculosis in our area continues to be a major health problem, especially among foreign-born children. As drug-resistant strains are increasing, initial therapy with 4 drugs is recommended in our population.

Gastric lavage in the diagnosis of pulmonary tuberculosis in children: a systematic review

OBJECTIVE

To analyze standardization of gastric lavage protocols in the diagnosis of pulmonary tuberculosis in children.

METHODS

A systematic review was conducted for the period between 1968 and 2008 in the following databases: LILACS, SCIELO and MEDLINE. The search strategy included the following terms: "gastric lavage and tuberculosis" or "gastric washing and tuberculosis" with the restriction of "children aged up to 15 years;" "gastric lavage and tuberculosis and childhood" or "gastric washing and tuberculosis and childhood." There were retrieved 80 articles and their analysis was based on information on the gastric lavage protocol for the diagnosis of pulmonary tuberculosis in children: preparation of children and fasting; time of gastric aspiration; aspiration of gastric residues; total volume of aspirate; solution used for aspiration of gastric contents; decontaminant solution; buffer solution; and time for forwarding samples to the laboratory. After a thorough analysis, 14 articles were selected.

RESULTS

No article detailed the whole procedure. Some articles had missing information on: amount of gastric aspirate; aspiration before or after solution injection; solution used for gastric aspiration; buffer solution used; and waiting time between specimen collection and laboratory processing. These results showed inconsistencies of gastric lavage protocols.

CONCLUSIONS

Although gastric lavage is a secondary diagnostic approach used only in special cases that did not reach the diagnostic scoring as recommended by the Brazilian Ministry of Health, there is a need to standardize gastric lavage protocols for the diagnosis of pulmonary tuberculosis in children.

Consensus statement on childhood tuberculosis

JUSTIFICATION

Revised National Tuberculosis Control Program (RNTCP) has focused on adults with smear positivity a tool not so well used in children with tuberculosis. There is a need to redefine standardization of diagnosis and management protocols for childhood tuberculosis.

PROCESS

Indian Academy of Pediatrics constituted a Working Group to develop consensus statement on childhood tuberculosis (TB). Members of the Group were given individual responsibilities to review the existing literature on different aspects of the childhood TB. The group deliberated and developed a consensus which was circulated to all the members for review. Efforts were made to ensure that the recommendations are standardized.

OBJECTIVES

To produce recommendations and standard protocols for reasonably accurate diagnosis and rational treatment of tuberculosis in children.

RECOMMENDATIONS

Fever and or cough > 2 weeks with loss of weight and recent contact with infectious case should arouse suspicion of TB. Chest Xray and trial with broad-spectrum antibiotic for 7-10 days is justified. In case of clinical and radiological non-response, Mantoux test and sputum or gastric aspirate for AFB is recommended. If AFB is positive, diagnosis is confirmed. If AFB is negative but chest Xray is suggestive and Mantoux test is positive, it is a probable case and if these tests are negative, alternate diagnosis must be sought and referral made to an expert. Ideally it is recommended to use 1TU of PPD for Mantoux test but 2 or 5 TU may be acceptable (but less preferred). Cut-off point of 10 mms for natural infection may be used for test done with 1, 2 or 5 TU. There is no linear relation of reaction to tuberculin strength and so no more than 5 TU should be used. BCG test is not recommended. Diagnosis must not be made without an attempt to look for AFB in gastric aspirate or sputum, as it is possible to get AFB even in primary complex. Elisa and PCR tests for TB are not recommended. There is no place for trial of anti tubercular therapy. Lymphnode enlargement > 2 cm with or without typical findings suggestive of TB and failure of antibiotic response demands FNAC for histopathology and bacteriology. Clinical suspicion of tubercular meningitis (TBM) should be confirmed by CSF examination and CT scan though none of these investigations are confirmatory and hence should not be considered in isolation. CSF tests for TB antibody and PCR are not recommended for routine use. Diagnosis of abdominal TB is made on circumstantial evidence and there are no standard guidelines. For treatment, disease is divided into three categories. The Category I and III are recommended for different types of new cases i.e. those who have received treatment for not more than 4 weeks. Category III includes primary pulmonary complex, one site peripheral lymphadenitis and pleural effusion, while all other forms of TB are included in Category I, that corresponds to smear positive TB in adults. This is because AFB is often found in many Category I disease in children. Category II includes defaulters, relapses and failure cases irrespective of the site of disease. Standard protocol is followed for each of these categories. Intermittent thrice weekly therapy with higher dose has been found to be equally effective as daily therapy and so is recommended in DOTS Direct Observed Therapy Short term. Compliance of treatment must be ensured. Repeat chest X-ray is ideal at the end of therapy. Liver function tests are not routinely recommended. Recommendations are also made for special situations such as MDRTB, TB and HIV and neonate born to mother suffering from TB.

[Diagnosis of tuberculosis in pediatrics. Consensus document of the Spanish Society of Pediatric Infectology (SEIP) and the Spanish Society of Pediatric Pneumology (SENP)]

Tuberculosis is one of the most important health problems worldwide. There are an increased number of cases, including children, due to different reasons in developed countries. The most likely determining cause is immigration coming from high endemic areas. Measures to optimize early and appropriate diagnosis of the different forms of tuberculosis in children are a real priority. Two Societies of the Spanish Pediatric Association (Spanish Society of Pediatric Infectology and Spanish Society of Pediatric Pneumology) have agreed this Consensus Document in order to homogenize diagnostic criteria in pediatric patients.

Acurácia do lavado gástrico realizado em ambiente hospitalar e ambulatorial no diagnóstico da tuberculose pulmonar em crianças

OBJETIVO: Comparar a acurácia do lavado gástrico (LG) realizado em ambiente hospitalar e ambulatorial no diagnóstico da tuberculose (TB) pulmonar em crianças. MÉTODOS: Estudo prospectivo realizado no Estado do Espírito Santo, Brasil, de 1999 a 2003. Um total de 230 crianças com suspeita de TB foi selecionado para realizar exame de LG em ambiente hospitalar (n = 103) ou em ambiente ambulatorial (n = 127). Desse total, 53 foram diagnosticadas como casos de TB e divididas em dois grupos: LG hospitalar (n = 30) e LG ambulatorial (n = 23). Todas as 53 crianças foram monitoradas por 6 meses para avaliação da acurácia do diagnóstico. A acurácia foi determinada com base na mudança do diagnóstico, na taxa de cura e no percentual de culturas positivas nos dois grupos estudados. RESULTADOS: A taxa de cura foi de 100% nos dois grupos, e não houve mudança de diagnóstico nas 53 crianças estudadas. Nenhuma diferença significativa foi encontrada entre os dois grupos estudados em relação ao achado do Mycobacterium tuberculosis (RR = 1,47; IC95%: 0,95-2,27; p = 0,095), apesar de o grupo LG ambulatorial ter apresentado o maior índice de cultura positivas. CONCLUSÕES: Nossos resultados mostram que a acurácia do LG realizado em ambiente hospitalar é semelhante à do realizado em ambiente ambulatorial, o que indica que a internação é necessária apenas em casos mais graves nos quais não se pode realizar o procedimento em ambiente ambulatorial.

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.

Increased reported cases of tuberculosis among children younger than 5 years of age, Maricopa County, Arizona, 2002-2003

OBJECTIVES

Although tuberculosis (TB) rates in the United States among children younger than 5 years old (2.8/100,000 in 2003) have been declining, Maricopa County, Arizona, reported an increase from 4.1/100,000 in 2002 to 9.0/100,000 in 2003. We investigated factors associated with this increase.

METHODS

We reviewed county TB clinic records of pediatric patients (younger than 5 years old) and their probable adult sources, interviewed parents or guardians of pediatric TB patients and examined changes in clinic procedures.

RESULTS

We verified 11 pediatric TB cases in 2002 and 25 in 2003 (n = 36). A total of 31 (86%) patients were born in the United States, and 28 (78%) had at least 1 foreign-born parent. There were 19 children (53%) identified from an adult TB contact investigation. Of children with identified sources (n = 24, 67%), 23 (96%) had probable household transmission; 20 (83%) had a foreign-born relative from a TB-endemic country as the probable source. Seven (50%) of 14 adult sources investigated had a delayed TB diagnosis. In 2003, increased TB clinic staffing, more frequent pediatric TB clinics and on-site gastric aspirates for TB diagnosis contributed to 55% more children being evaluated for TB.

CONCLUSIONS

Close interaction with family members and delayed diagnoses were the primary means of TB transmission to children. The increase in pediatric TB likely reflects improved clinic diagnostic capacity and may indicate a more accurate baseline rate for Maricopa County. Programmatic improvements in TB control and targeted outreach to high-risk immigrant populations may increase pediatric and adult source case detection and reduce Mycobacterium tuberculosis transmission.

Tuberculosis in children: an update

TB is a common and serious global infection that is spread exclusively from person to person. The initial infection in most healthy people leads to LTBI 95% of the time, but untreated individuals have a 5% to 10% lifetime risk for reactivating their infection to develop highly infectious cavitary pulmonary TB or extrapulmonary disease. Following primary infection progressive disease is more likely to develop in children younger than 5 years old or those who are immunocompromised, particularly those with HIV infection. The diagnosis of TB in most of the world depends on the presence of a clinical illness typical for TB in concert with radiographic changes, the presence of AFB in sputum, or a positive TST. Newer methods of in vitro stimulation of T lymphocytes from TB-infected people to produce interferon may be more accurate than a TST but have yet to be well studied in children. Treatment of children with LTBI is generally 9 months of daily isoniazid unless the child has been in contact with an adult with known isoniazid-resistant TB. For active TB, children generally are treated for 6 months with an initial 2 months of isoniazid, rifampin, and pyrazinamide. Where exposure to an isoniazid-resistant strain is likely, ethambutol is added. After 2 months, pyrazinamide is discontinued unless the patient has been confirmed to have been infected with a resistant strain of M. tuberculosis. BCG, rarely used in the United States, is still considered important to prevent meningitis and miliary disease in very young children in areas of the world with a high prevalence of TB.

Tuberculosis in children

The epidemiology of pediatric tuberculosis (TB) is shaped by risk factors such as age, race, immigration, poverty, overcrowding, and HIV/AIDS. Once infected, young children are at increased risk of TB disease and progression to extrapulmonary disease. Primary disease and its complications are more common in children than in adults, leading to differences in clinical and radiographic manifestations. Difficulties in diagnosing children stem from the low yield of mycobacteriology cultures and the subsequent reliance on clinical case definitions. Inadequately treated TB infection and TB disease in children today is the future source of disease in adults.

Induced sputum versus gastric lavage for microbiological confirmation of pulmonary tuberculosis in infants and young children: a prospective study

BACKGROUND

For microbiological confirmation of diagnosis of pulmonary tuberculosis in young children, sequential gastric lavages are recommended; sputum induction has not been regarded as feasible or useful. We aimed to compare the yield of Mycobacterium tuberculosis from repeated induced sputum with that from gastric lavage in young children from an area with a high rate of HIV and tuberculosis.

METHODS

We studied 250 children aged 1 month to 5 years who were admitted for suspected pulmonary tuberculosis in Cape Town, South Africa. Sputum induction and gastric lavage were done on three consecutive days according to a standard procedure. Specimens were stained for acid-fast bacilli; each sample was cultured singly for M tuberculosis.

FINDINGS

Median age of children was 13 months (IQR 6-24). A positive smear or culture for M tuberculosis was obtained from 62 (25%) children; of these, 58 (94%) were positive by culture, whereas almost half (29 [47%]) were smear positive. Samples from induced sputum and gastric lavage were positive in 54 (87%) and 40 (65%) children, respectively (difference in yield 5.6% [1.4-9.8%], p=0.018). The yield from one sample from induced sputum was similar to that from three gastric lavages (p=1.0). Microbiological yield did not differ between HIV-infected and HIV-uninfected children (p=0.17, odds ratio 0.7 [95% CI 0.3-1.3]). All sputum induction procedures were well tolerated; minor side-effects were increased coughing, epistaxis, vomiting, or wheezing.

INTERPRETATION

Sputum induction is safe and useful for microbiological confirmation of tuberculosis in young children. This technique is preferable to gastric lavage for diagnosis of pulmonary tuberculosis in both HIV-infected and HIV-uninfected infants and children.

Cavitating tuberculosis in an infant: case report and literature review

Primary cavitating tuberculosis is a rare complication of primary tuberculosis in young children. In the absence of a known adult source case, the diagnosis of tuberculosis in children can be difficult. We describe an 8-month-old baby with primary cavitating tuberculosis, in whom there was considerable delay in diagnosis, and review the literature.

Identifying the sources of tuberculosis in young children: a multistate investigation

To better understand the molecular epidemiology of tuberculosis (TB) transmission for culture-confirmed patients <5 years of age, data were analyzed from a population-based study conducted in seven U.S. sites from 1996 to 2000. Mycobacterium tuberculosis isolates were genotyped with IS6110-based restriction fragment length polymorphism analysis and spoligotyping. Case-patient data were obtained from the Centers for Disease Control and Prevention s national tuberculosis registry and health department records. Routine public health investigations conducted by local health departments identified suspected source patients for 57 (51%) of 111 culture-confirmed patients <5 years of age. For 8 (15%) of 52 culture-confirmed patients <5 years of age and their suspected source patients with complete genotyping results, genotypes suggested infection with different TB strains. Potential differences between sources for patients <5 years of age and source patients that transmitted TB to adolescent and adult patients were identified.

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.

Diagnostic techniques in paediatric tuberculosis

Accurate diagnosis of tuberculosis (TB) in children is crucial to provide effective treatment and to identify the undiagnosed adult who probably infected the child. The diagnosis of tuberculosis in children is often based only on epidemiologic, clinical, and radiographic findings. Fibre-optic bronchoscopy may also be helpful but the recovery of tuberculous bacilli, which establishes the diagnosis, is difficult in children. Rapid diagnostic tests such as direct amplification and serological tests have been developed to improve early diagnosis. Their sensitivity is higher than that of conventional mycobacterial culture in most paediatric studies.

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.