Latent tuberculosis infection in children: a call for revised treatment guidelines

Isoniazid-resistant tuberculosis: a cause for concern?

The drug isoniazid (INH) is a key component of global tuberculosis (TB) control programmes. It is estimated, however, that 16.1% of TB disease cases in the former Soviet Union countries and 7.5% of cases outside of these settings have non-multidrug-resistant (MDR) INH resistance. Resistance has been linked to poorer treatment outcomes, post-treatment relapse and death, at least for specific sites of disease. Multiple genetic loci are associated with phenotypic resistance; however, the relationship between genotype and phenotype is complex, and restricts the use of rapid sequencing techniques as part of the diagnostic process to determine the most appropriate treatment regimens for patients. The burden of resistance also influences the usefulness of INH preventive therapy. Despite seven decades of INH use, our knowledge in key areas such as the epidemiology of resistant strains, their clinical consequences, whether tailored treatment regimens are required and the role of INH resistance in fuelling the MDR-TB epidemic is limited. The importance of non-MDR INH resistance needs to be re-evaluated both globally and by national TB control programmes.

Missed opportunities for tuberculosis screening in primary care

OBJECTIVE

To assess how frequently pediatric practitioners perform latent tuberculosis infection (LTBI) screening according to guidelines. We hypothesized that screening occurs less frequently among children whose parents do not speak English as the primary language.

STUDY DESIGN

We conducted a retrospective cohort study of patients attending well-child visits in an urban academic pediatric primary care clinic between April 1, 2012, and March 31, 2013. We assessed documentation of 3 LTBI screening components and tested the association between parent primary language and tuberculin skin test (TST) placement and documentation of results.

RESULTS

During the study period, 387 of 9143 children (4%) had no documentation of screening question responses. Among the other 8756 children, 831 (10%) were identified as at high risk for LTBI. Of these, 514 (62%) did not have documented TST placement in the appropriate time frame. Thirty-nine of 213 children (18%) who had a TST placed did not have documented results. Multivariable regression showed that parent language was not associated with TST placement or documentation of results, but non-Hispanic Black children were more likely to not have a documented test result (aOR, 2.12; 95% CI, 1.07-4.19; P=.03) when adjusting for age, sex, parent primary language, insurance status, day of the week, and study year of TST placement.

CONCLUSION

Parent primary language was not associated with LTBI testing. However, we found substantial gaps in TST placement and documentation of TST results among high-risk children, the latter of which was associated with race/ethnicity. Targeted quality improvement efforts should focus on developing processes to ensure complete screening in high-risk children.

Treatment of Latent Tuberculosis Infection in Children

Treatment of latent tuberculosis infection (LTBI) is an effective way of preventing future cases of tuberculosis disease. We review pediatric and adult studies of LTBI treatment (isoniazid and rifampin monotherapy, isoniazid plus rifampin, isoniazid plus rifapentine, and rifampin plus pyrazinamide). Based upon this review and our pediatric experience, we can offer recommendations for routine (isoniazid) and alternative courses of therapy.

Cost-effectiveness of latent tuberculosis screening before steroid therapy for idiopathic nephrotic syndrome in children

BACKGROUND

Guidelines differ on screening recommendations for latent tuberculosis infection (LTBI) prior to immunosuppressive therapy. We aimed to determine the most cost-effective LTBI screening strategy before long-term steroid therapy in a child with new-onset idiopathic nephrotic syndrome.

STUDY DESIGN

Markov state-transition model.

SETTING & POPULATION

5-year-old boy with new-onset idiopathic nephrotic syndrome.

MODEL, PERSPECTIVE, & TIMEFRAME

The Markov model took a societal perspective over a lifetime horizon.

INTERVENTION

3 strategies were compared: universal tuberculin skin testing (TST), targeted screening using a risk-factor questionnaire, and no screening. A secondary model included the newer interferon γ release assays (IGRAs), requiring only one visit and having greater specificity than TST.

OUTCOMES

Marginal cost-effectiveness ratios (2010 US dollars) with effectiveness measured as quality-adjusted life-years (QALYs).

RESULTS

At an LTBI prevalence of 1.1% (the average US childhood prevalence in our base case), a no-screening strategy dominated ($2,201; 29.3356 QALYs) targeted screening ($2,218; 29.3356 QALYs) and universal TST ($2,481; 29.3347 QALYs). At a prevalence >10.3%, targeted screening with a risk-factor questionnaire was the most cost-effective option. Higher than a prevalence of 58.5%, universal TST was preferred. In the secondary model, targeted screening with a questionnaire followed by IGRA testing was cost-effective compared with no screening in the base case when the LTBI prevalence was >4.9%.

LIMITATIONS

There is no established gold standard for the diagnosis of LTBI. Results of any modeling task are limited by the accuracy of available data.

CONCLUSIONS

Prior to starting steroid therapy, only patients in areas with a high prevalence of LTBI will benefit from universal TST. As more evidence becomes available about the use of IGRA testing in children, the assay may become a component of cost-effective screening protocols in populations with a higher burden of LTBI.

Pediatric and adolescent tuberculosis in the United States, 2008-2010

OBJECTIVE

We examined heterogeneity among children and adolescents diagnosed with tuberculosis (TB) in the United States, and we investigated potential international TB exposure risk.

METHODS

We analyzed demographic and clinical characteristics by origin of birth for persons <18 years with verified case of incident TB disease reported to National TB Surveillance System from 2008 to 2010. We describe newly available data on parent or guardian countries of origin and history of having lived internationally for pediatric patients with TB (<15 years of age).

RESULTS

Of 2660 children and adolescents diagnosed with TB during 2008-2010, 822 (31%) were foreign-born; Mexico was the most frequently reported country of foreign birth. Over half (52%) of foreign-born patients diagnosed with TB were adolescents aged 13 to 17 years who had lived in the United States on average >3 years before TB diagnosis. Foreign-born pediatric patients with foreign-born parents were older (mean, 7.8 years) than foreign-born patients with US-born parents (4.2 years) or US-born patients (3.6 years). Among US-born pediatric patients, 66% had at least 1 foreign-born parent, which is >3 times the proportion in the general population. Only 25% of pediatric patients with TB diagnosed in the United States had no known international connection through family or residence history.

CONCLUSIONS

Three-quarters of pediatric patients with TB in the United States have potential TB exposures through foreign-born parents or residence outside the United States. Missed opportunities to prevent TB disease may occur if clinicians fail to assess all potential TB exposures during routine clinic visits.

Preventive therapy in children exposed to Mycobacterium tuberculosis: problems and solutions

Young children living with a tuberculosis patient are at high risk of Mycobacterium tuberculosis infection and disease. WHO guidelines promote active screening and isoniazid (INH) preventive therapy (PT) for such children under 5 years, yet this well-established intervention is seldom used in endemic countries. We review the literature regarding barriers to implementation of PT and find that they are multifactorial, including difficulties in screening, poor adherence, fear of increasing INH resistance and poor acceptability among primary caregivers and healthcare workers. These barriers are largely resolvable, and proposed solutions such as the adoption of symptom-based screening and shorter drug regimens are discussed. Integrated multicomponent and site-specific solutions need to be developed and evaluated within a public health framework to overcome the policy-practice gap and provide functional PT programmes for children in endemic settings.

Clinical perspectives of childhood tuberculosis in Taiwan

Tuberculosis (TB) is an important public health issue in Taiwan and worldwide. Taiwan has made major progress in combating TB in the past 40 years. However, childhood TB still constitutes a significant challenge in disease control. From January to mid December 2011, 369 new cases of pediatric TB were confirmed. The relatively low case number and variable clinical presentations made it difficult for early detection. Latent TB infections in children also pose further complexity in clinical management. Knowledge of the clinical features of active and latent TB infection is crucial for efficient TB control.

Tuberculosis in special populations

The susceptibility to infection, the pathogenesis and the clinical manifestations of tuberculosis (TB) depend on the immunological status of the host. Immunological status is largely determined by age and comorbidities, but is also affected by other less well known factors. In Spain, most incidental cases of TB arise from the reactivation of remotely acquired latent infections and are favored by the aging of the population and the use of aggressive immunosuppressive therapies. The diagnosis and management of TB in these circumstances is often challenging. On the one hand, the atypical presentation with extrapulmonary involvement may delay diagnosis, and on the other, the toxicity and interactions of the antituberculous drugs frequently make treatment difficult. Immigration from resource-poor, high incidence TB countries, where the social and economic conditions are often suboptimal, adds a new challenge to the control of the disease in Spain. This chapter summarizes our current knowledge of epidemiological, clinical and treatment aspects of TB in particularly susceptible populations.

Latent tuberculosis in children: diagnosis and management

Control of tuberculosis in children often escapes attention because of the paucibacillary nature of the illness. However, they contribute much of the morbidity, mortality and future reservoir of the disease which reiterates the importance of risk-factor based screening for latent infection and appropriate treatment. We review the modalities and importance of diagnosis and treatment of latent tuberculosis infection in children. At this time, the role for interferon-gamma release assays in low-income, high-burden settings is rather limited but further research in the coming years might clear their role in children. An important emerging area of research is the development of an improved skin test for TB that uses specific mycobacterial antigens rather than tuberculin, thus is more feasible and useful in resource limited settings.

High prevalence of childhood multi-drug resistant tuberculosis in Johannesburg, South Africa: a cross sectional study

BACKGROUND

There are limited data on the prevalence of multi-drug resistant tuberculosis (MDR-TB), estimated at 0.6-6.7%, in African children with tuberculosis. We undertook a retrospective analysis of the prevalence of MDR-TB in children with Mycobacterium tuberculosis (MTB) at two hospitals in Johannesburg, South Africa.

METHODS

Culture-confirmed cases of MTB in children under 14 years, attending two academic hospitals in Johannesburg, South Africa during 2008 were identified and hospital records of children diagnosed with drug-resistant TB were reviewed, including clinical and radiological outcomes at 6 and 12 months post-diagnosis. Culture of Mycobacterium tuberculosis complex (MTB) was performed using the automated liquid broth MGIT™ 960 method. Drug susceptibility testing (DST) was performed using the MGIT™ 960 method for both first and second-line anti-TB drugs.

RESULTS

1317 children were treated for tuberculosis in 2008 between the two hospitals where the study was conducted. Drug susceptibility testing was undertaken in 148 (72.5%) of the 204 children who had culture-confirmed tuberculosis. The prevalence of isoniazid-resistance was 14.2% (n = 21) (95%CI, 9.0-20.9%) and the prevalence of MDR-TB 8.8% (n = 13) (95%CI, 4.8-14.6%). The prevalence of HIV co-infection was 52.1% in children with drug susceptible-TB and 53.9% in children with MDR-TB. Ten (76.9%) of the 13 children with MDR-TB received appropriate treatment and four (30.8%) died at a median of 2.8 months (range 0.1-4.0 months) after the date of tuberculosis investigation.

CONCLUSIONS

There is a high prevalence of drug-resistant tuberculosis in children in Johannesburg in a setting with a high prevalence of HIV co-infection, although no association between HIV infection and MDR-TB was found in this study. Routine HIV and drug-susceptibility testing is warranted to optimize the management of childhood tuberculosis in settings such as ours.