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

Performance of Tuberculin Skin Tests and Interferon-γ Release Assays in Children Younger Than 5 Years

BACKGROUND

Available data to assess the optimal diagnostic approach in infants and preschool children at risk of tuberculosis (TB) are limited.

METHODS

We conducted a prospective observational study in children younger than 5 years undergoing assessment with both tuberculin skin tests (TST) and QuantiFERON-TB Gold In-Tube (QFT-GIT) assays at 2 tertiary TB units in Barcelona, Spain.

RESULTS

A total of 383 children were included. One of 304 participants considered uninfected developed active TB during follow-up {median [interquartile range (IQR)]: 47 [30; 48] months}, compared with none of 40 participants with latent TB infection [follow-up since completion of anti-TB treatment: 42 (32; 45) months]. Overall test agreement between TST and QFT-GIT was moderate (κ = 0.551), but very good in children screened after TB contact (κ = 0.801) and in Bacillus Calmette-Guérin (BCG)-unvaccinated children (κ = 0.816). Discordant results (16.8%, all TST+/QFT-GIT-) were mainly observed in new-entrant screening and in BCG-vaccinated children. Children with indeterminate QFT-GIT results were on average younger than those with determinate results (median age: 12 vs. 30 months; P < 0.001). The sensitivity of TSTs and QFT-GIT assays in children with confirmed active TB was 100% (95% confidence interval: 79.4%-100%) and 93.7% (95% confidence interval: 69.8%-99.8%), respectively. In patients with latent TB infection or active TB, there was no correlation between age and antigen-stimulated interferon-γ responses (r = -0.044; P = 0.714).

CONCLUSIONS

In young BCG-unvaccinated children with recent TB contact, a dual testing strategy using TST and QFT-GIT in parallel may not be necessary. However, TST+/QFT-GIT- discordance is common, and it remains uncertain if this constellation indicates TB infection or not. In active TB, QFT-GIT assays do not perform better than TSTs.

Implementation challenges of a TB programme in rural northern mozambique: evaluation of 2012-2013 outcomes

BACKGROUND

We aimed to identify challenges and to propose solutions for the implementation of tuberculosis (TB) programmes in rural Sub-Saharan Africa (SSA) by evaluating the outcomes of the TB programme in the Ancuabe district in rural Northern Mozambique.

METHODS

Retrospective descriptive study of the patients included in the TB programme in 2012-2013. Follow-up was continued till June 2014.

RESULTS

Three hundred nineteen patients were registered, 62.1% male, mean age 36.3 (SD 14.4), estimated case detection rate (eCDR) of 24.24%. Two hundred seventy-two were new cases, 21 transferred-in, 11 back after lost to follow-up (LTFU), 10 relapsing TB, 5 previous treatment failures. 94.4% were tested for Human immunodeficiency virus (HIV), 41.9% HIV-positive. 87.5% of the new cases were pulmonary TB (PTB), 43.4% were HIV co-infected. Initial sputum results were available in 207 cases, with 145 smear-positive (SP) cases. Outcomes of new cases: 122 (44.9%) LTFU, 55 (20.2%) cured, 43 (15.8%) treatment completed (98-36%-treatment success), 31 (11.4%) died, 19 (7%) transferred out and 2 (0.7%) failures.

CONCLUSIONS

A low eCDR and high proportion of LTFU demonstrate that few patients were identified and had a low probability of complete treatment, suggesting a fragile health system. This raises the hypothesis that, probably, to improve TB health care in rural SSA, interventions should aim at improving health systems. Special attention should be given to social protection and compensation of the financial burden associated with TB.

Microscopic observation drug susceptibility assay for the diagnosis of TB and MDR-TB in HIV-infected patients: a systematic review and meta-analysis

The objective of the present study was to assess the diagnostic accuracy of the microscopic observation drug susceptibility (MODS) assay for tuberculosis (TB) diagnosis in HIV-infected patients. MEDLINE, EMBASE, LILACS, the Cochrane Central Register of Controlled Trials, African Index Medicus, ResearchGate, SciELO, and the abstracts of the main conferences on infectious diseases and tropical medicine were searched, and other sources investigated. Only studies including HIV-infected patients evaluating MODS for the diagnosis of TB and using culture-based diagnostic tests as a gold standard were analysed. Summary sensitivity and specificity were calculated with a bivariate model. 3259 citations were found, 29 were selected for full-text review and 10 studies including 3075 samples were finally analysed. Overall diagnostic accuracy of MODS for the diagnosis of TB was a sensitivity of 88.3% (95% CI 86.18-90.2%) and specificity 98.2% (95% CI 97.75-98.55%). For multidrug-resistant (MDR)-TB, sensitivity was 89% (95% CI 66.07-97%) and specificity was 100% (95 CI 94.81-100%). For smear-negative pulmonary TB, a sensitivity of 88.2% (95% CI 86.1-89.9%) and specificity of 98.2% (95% CI 96.8-98.9%) were found. Costs varied between USD 0.72 and 7.31 per sample. Mean time to positivity was 8.24 days. MODS was found to have a good accuracy for the diagnosis of TB and MDR-TB in HIV-infected patients with low cost and fast results.