Diagnosis of latent tuberculosis infection among pediatric household contacts of Iranian tuberculosis cases using tuberculin skin test, IFN- γ release assay and IFN-γ-induced protein-10

Effect of tuberculosis-specific antigen stimulation on the diagnostic accuracy of interferon-γ inducible protein-10 in distinguishing active and latent tuberculosis infection: a meta-analysis

BACKGROUND

Identifying active tuberculosis (ATB) from latent tuberculosis infection (LTBI) persists as a challenge, and interferon-γ inducible protein-10 (IP-10) has been employed as the solution. To further improve its diagnostic performance, the sample can be stimulated with TB specific antigen (TBAg).

AIM

To perform meta-analysis on diagnostic accuracy of unstimulated and TBAg-stimulated IP-10 in differentiating ATB from LTBI.

METHODS

Systematic search was performed on five major scientific databases as of 29 November 2023. Observational studies reporting diagnostic values of unstimulated or TBAg-stimulated IP-10 in identifying ATB from LTBI were included. Meta-analysis was carried out using two-level mixed-effect logistic regression model.

RESULTS

Twenty-five studies recruiting 2301 patients (1137 ATB versus 1164 LTBI) were included in the quantitative analysis. The pooled sensitivity and specifity of IP-10 were 72% (95%CI: 0.59-0.82) and 78% (95%CI: 0.63-0.88), respectively. As for TBAg-stimulated IP-10, the sensitivity and specifity were 82% (95%CI: 0.76-0.87) and 85% (95%CI: 0.73-0.92), respectively. The senstivity was reduced signiticantly (p < 0.01) when the patients with human immunodeficiency virus infection were included, except after the TBAg stimulation.

CONCLUSION

Stimulating IP-10 with TBAg could improve the diagnostic accuracy in differentiating ATB from LTBI.

Management implications of latent TB among under-five children at risk: Insights from a community study in Mumbai, India

BACKGROUND

Latent tuberculosis infection (LTBI) management is crucial to WHO's End TB Strategy. Indian guidelines recommend treating under-five children with household TB contacts after ruling out active TB, regardless of TBI testing. However, the precise LTBI burden among children in high TB burden settings like India is unknown. A community-based study in Mumbai's urban slums screened and managed under-five children at LTBI risk to understand its epidemiology and inform TB control interventions.

METHODS

Total 369 eligible under-five children were enrolled for the study. LTBI screening was done using Tuberculin skin test and Interferon gamma release assay. Active TB was ruled out before initiation of TB preventive therapy among LTBI positives. Statistical tests like chi-square, logistic regression analysis and Hosmer-Lemeshow test were used.

RESULTS

Overall, LTBI prevalence among under-five children was 12.4% by IGRA and 21.4% by TST. Undernourished children had significantly lower LTBI positivity by IGRA (p = 0.027), while those with household contacts, longer contact duration and drug-resistant tuberculosis (DR-TB) exhibited proportionally greater IGRA positivity (p = <0.001).

CONCLUSION

The study found a lower LTBI prevalence among under-five children compared to adults, with key risk factors being HHC, DR-TB contact, and prolonged exposure. These findings suggest the need to revise or revisit the TPT framework for this age group in India, particularly by implementing a test-and-treat approach.

QuantiFERON-TB Gold Plus Performance in Children: A Narrative Review

This review summarizes studies evaluating the performance of the QuantiFERON-TB Gold Plus (QFT-Plus) interferon-gamma release assay (IGRA) test for Mycobacterium tuberculosis ( Mtb ) infection in children. Literature searching was conducted using PubMed, MEDLINE and Embase (January 2017 to December 2021) and the terms "children" or "pediatric" and "IGRAs" or "QuantiFERON-TB Gold Plus." Selected studies (N = 14; 4646 subjects) enrolled children with Mtb infection, tuberculosis (TB) disease or healthy children with household TB contacts. Agreement between QFT-Plus and tuberculin skin test (TST) (kappa values) ranged from -0.201 (no agreement) to 0.83 (almost perfect agreement). Assay sensitivity of QFT-Plus (against reference standard of microbiologically confirmed TB disease) was 54.5%-87.3%, with no reported difference in children less than 5 versus greater than or equal to 5 years of age. In individuals less than or equal to 18 years of age, the rate of indeterminate results was 0%-33.3% (2.6% in children <2 years). IGRAs may overcome the limitations of TST in young, Bacillus Calmette-Guérin-vaccinated children.

Interferon-Inducible Protein-10 as a Marker to Detect Latent Tuberculosis Infection in Patients with Inflammatory Rheumatic Diseases

It is important to identify cases of latent tuberculosis infection (LTBI) who are at risk for tuberculosis (TB) reactivation. We aimed to evaluate the performance of interferon (IFN)-gamma-inducible protein 10 (IP-10) as a marker to detect LTBI in patients with inflammatory rheumatic diseases (IRD). This study comprised 76 consecutive subjects with IRD. Patients with a history of TB or having active TB were excluded. In all patients, IP-10 level was measured and tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube test (QFT-GIT) were performed. Seventy patients with complete test results were analyzed. Twenty-one (30%) QFT-GIT-positive patients were defined as having LTBI. IP-10 yielded 2197 pg/mL cut-off point. At this cut-off point, IP-10 showed 89% specificity with a sensitivity of 91% (AUC: 0.950, 95% CI 0.906–0.994). TST, QFT-GIT, and IP-10 were positive in 77.1%, 30%, and 44.3% of the patients, respectively. Concordance among the results of TST, QFT-GIT, and IP-10 tests was evaluated. Agreement was poor between IP-10 and TST (58.6%, κ = 0.19), whereas it was good between QFT-GIT and IP-10 (84.3%, κ = 0.65). The results of the present study demonstrated that sensitivity and specificity of released IP-10 were as high as those of QFT-GIT in indicating LTBI in IRD patient group.