Tuberculosis in children

Tuberculosis diagnostic accuracy of stool Xpert MTB/RIF and urine AlereLAM in vulnerable children

BACKGROUND

Non-sputum based diagnostic approaches are crucial in children at high risk of disseminated tuberculosis [TB] who cannot expectorate sputum. We evaluated the diagnostic accuracy of Xpert MTB/RIF from stool and urine AlereLipoarabinomannan [LAM] test in this group of children.

METHODS

Hospitalised children with presumptive TB and either age <2 years, HIV-positive or severe malnutrition were enrolled in a diagnostic cohort. At enrolment, we attempted to collect two urine, two stool and two respiratory samples. Urine and stool were tested with AlereLAM and Xpert MTB/RIF, respectively. Respiratory samples were tested with Xpert MTB/RIF and mycobacterial culture. Both a microbiological and a composite clinical reference standard were used.

RESULTS

The study enrolled 219 children; median age 16.4 months, 72 (32.9%) HIV-positive and 184 (84.4%) severely malnourished. Twelve (5.5%) and 58 (28.5%) children had confirmed and unconfirmed TB respectively. Stool and urine were collected in 219 (100%) and 216 (98.6%) children. Against the microbiological reference standard the sensitivity and specificity (n/N, 95% confidence intervals) of stool Xpert MTB/RIF was 50.0% (6/12, 21.1-78.9) and 99.1% (198/200 96.4-99.9), while that of urine AlereLAM was 50.0% (6/12, 21.1-78.9) and 74.6% (147/197, 67.9-80.5) respectively. Against the composite reference standard sensitivity was reduced to 11.4% (8/70) for stool and 26.2% (17/68) for urine, with no major difference by age group (<2 and >2 years) or HIV status.

CONCLUSION

The Xpert MTB/RIF assay has excellent specificity on stool, but sensitivity is suboptimal. Urine AlereLAM is compromised by poor sensitivity and specificity in children.

Longitudinal analysis of QuantiFERON-TB Gold In-Tube in children with adult household tuberculosis contact in South Africa: a prospective cohort study

BACKGROUND

QuantiFERON-TB Gold In Tube (QFT-GIT) is a tool for detecting M. tuberculosis infection. However, interpretation and utility of serial QFT-GIT testing of pediatric tuberculosis (TB) contacts is not well understood. We compared TB prevalence between baseline and 6 months follow-up using QFT-GIT and tuberculin skin testing (TST) in children who were household contacts of adults with pulmonary TB in South Africa, and explored factors associated with QFT-GIT conversions and reversions.

METHOD

Prospective study with six month longitudinal follow-up.

RESULTS

Among 270 enrolled pediatric contacts, 196 (73%) underwent 6-month follow-up testing. The 6-month prevalence estimate of MTB infection in pediatric contacts increased significantly from a baseline of 29% (79/270, 95%CI [24-35]) to 38% (103/270, 95% CI [32-44], p<0.001) using QFT-GIT; prevalence increased from a baseline of 28% (71/254, 95%CI [23-34]) to 33% (88/263, 95%CI [21-32], p = 0.002) using TST. Prevalence estimates were influenced by thresholds for positivity for TST, but not for QFT-GIT. Among 134 children with a negative or indeterminate baseline QFT-GIT, 24 (18%) converted to positive at follow-up; conversion rates did not differ significantly when using more stringent thresholds to define QFT-GIT conversion. Older age >10 years (AOR 8.9 95%CI [1.1-72]) and baseline TST positivity ≥5 mm (AOR 5.2 95%CI [1.2-23]) were associated with QFT-GIT conversion. Among 62 children with a positive baseline QFT-GIT, 9 (15%) reverted to negative; female gender (AOR 18.5 95%CI [1.1-321]; p = 0.04] was associated with reversion, while children with baseline positive TST were less likely to have QFT-GIT reversion (AOR 0.01 95%CI [0.001-0.24]).

CONCLUSION

Among pediatric contacts of adult household TB cases in South Africa, prevalence estimates of TB infection increased significantly from baseline to 6 months. Conversions and reversions occurred among pediatric TB contacts using QFT-GIT, but QFT-GIT conversion rates were less influenced by thresholds used for conversions than were TST conversion rates.

Preparation and antitubercular activities in vitro and in vivo of novel Schiff bases of isoniazid

Structural modification of the frontline antitubercular isonicotinic acid hydrazide (INH) provides lipophilic adaptations (3-46) of the drug in which the hydrazine moiety of the parent compound has been chemically blocked from the deactivating process of N(2)-acetylation by N-arylaminoacetyl transferases. As a class, these compounds show high levels of activity against Mycobacterium tuberculosis in vitro and in tuberculosis-infected macrophages. They provide strong protection in tuberculosis-infected mice and have low toxicity. With some representatives of this class achieving early peak plasma concentrations approximately three orders of magnitude above minimum inhibitory concentration, they may serve as tools for improving our understanding of INH-based treatment modalities, particularly for those patients chronically underdosed in conventional INH therapy.

Epidemiology of childhood tuberculosis in the United States, 1993-2001: the need for continued vigilance

OBJECTIVE

To describe trends and highlight epidemiologic and clinical characteristics of childhood tuberculosis (TB) in the United States.

METHODS

All verified TB cases reported to the national TB surveillance system from 1993 to 2001 were included. A child was defined as a person younger than 15 years.

RESULTS

A total of 11,480 childhood TB cases were reported. Case rates (TB cases/100,000 population) in all children declined from 2.9 (n = 1663) in 1993 to 1.5 (n = 931) in 2001. Among children, those who were younger than 5 years had the highest rate. California, Texas, and New York accounted for 48% of all childhood TB cases. In 2001, TB case rates were higher for foreign-born (12.2) than US-born children (1.1). Hispanic and non-Hispanic black children accounted for nearly three quarters of all cases. Twenty-four percent of children with TB were foreign-born children, with the largest number originating from Mexico (39.8%), the Philippines (8.6%), and Vietnam (5.7%). Most children had evidence of pulmonary TB disease (78.9%). Among culture-positive cases without previous TB, drug resistance to at least isoniazid was 7.3% and to isoniazid and rifampin was 1.6%. In 1999, 82.9% of children received directly observed therapy for at least part of their treatment and 94.8% completed treatment.

CONCLUSIONS

Although the overall TB case number among children is declining in the United States, certain groups of children (eg, younger children, racial and ethnic minorities, foreign-born) are at higher risk for TB. As the United States moves toward the elimination of TB, future efforts should endeavor to prevent all cases of childhood TB.

Assessment of tuberculosis treatment completion in an ethnically diverse population using two data sources. Implications for treatment interventions

Many adolescents who are prescribed therapy for tuberculosis (TB) infection fail to complete it. This article presents the results of a demographic and epidemiological assessment of TB treatment completion in adolescent populations using (a) surveillance data from the Los Angeles Health County Department and (b) a prospective/retrospective medical chart review from targeted clinics. Patients who did not complete the 6-month recommended medical treatment for latent tuberculosis therapy (LTBI) averaged 13 weeks in care. Younger age (OR = 1.15; 95% CI 1.03-1.29), birth in the United States (OR = 1.92; 95% CI 1.14-3.22, compared to Mexico), and Asian ethnicity were associated with completion of care. In multiple logistic regression analysis, age (OR = .88; 95% CI .78-.98) and Latino ethnicity (OR = .53; 95% CI .29-.95) remained significant predictors of completion of treatment. These findings indicate the need for age-specific educational reinforcement and cultural differentials in completing care for LTBI.

Respiratory failure caused by tuberculous pneumonia requiring extracorporeal membrane oxygenation

While a common pathogen, Mycobacterium tuberculosis (TB) pneumonitis is only rarely reported as a cause for respiratory failure in developed countries. We report an adolescent with TB pneumonitis and respiratory failure requiring extracorporeal membrane oxygenation (ECMO) with eventual survival. With the incidence of TB rising globally, TB should be suspected and treated as early as possible. ECMO should be considered as a treatment option if conventional ventilatory support is inadequate. ECMO survival with TB pneumonia and anti-TB antimicrobial therapy is possible.

Evaluation of young children in household contact with adult multidrug-resistant pulmonary tuberculosis cases

BACKGROUND

The prevention and management of multidrug-resistant (MDR) tuberculosis has received much attention, but little attention has been given to children with MDR tuberculosis or children in contact with adults with MDR tuberculosis. The aim of this study was to determine the prevalence of tuberculous infection and disease in childhood contacts of adults with MDR pulmonary tuberculosis.

METHOD

All children <5 years of age in household contact with 75 recently diagnosed adults with MDR pulmonary tuberculosis were evaluated. Evaluation included clinical examination, tuberculin skin test, chest radiography and culture for Mycobacterium tuberculosis from gastric aspirates.

RESULTS

One hundred twenty-eight children, median age 27 months, were evaluated. Fifty children had recent contact with other adult tuberculosis cases. Sixty-six children previously had chemoprophylaxis or treatment of whom 36 defaulted treatment or received insufficient chemoprophylaxis. One child had HIV infection. Forty-seven children were classified as noninfected, 66 were considered infected only (Mantoux test, > or = 15 mm) and 15 had disease. Three children, who had not previously received antituberculosis drugs, had positive cultures for M. tuberculosis; all were multidrug-resistant.

CONCLUSION

This study documents the transmission of multidrug-resistant M. tuberculosis to childhood contacts, the development of disease in these contacts and the importance of knowing the index case's M. tuberculosis susceptibility pattern in choosing a proper treatment regimen for the childhood contact.