Performance of a rapid strip test for the serologic diagnosis of latent tuberculosis in children

Evaluation of serological assays for the diagnosis of childhood tuberculosis disease: a study protocol

BACKGROUND

Tuberculosis (TB) poses a major public health challenge, particularly in children. A substantial proportion of children with TB disease remain undetected and unconfirmed. Therefore, there is an urgent need for a highly sensitive point-of-care test. This study aims to assess the performance of serological assays based on various antigen targets and antibody properties in distinguishing children (0-18 years) with TB disease (1) from healthy TB-exposed children, (2) children with non-TB lower respiratory tract infections, and (3) from children with TB infection.

METHODS

The study will use biobanked plasma samples collected from three prospective multicentric diagnostic observational studies: the Childhood TB in Switzerland (CITRUS) study, the Pediatric TB Research Network in Spain (pTBred), and the Procalcitonin guidance to reduce antibiotic treatment of lower respiratory tract infections in children and adolescents (ProPAED) study. Included are children diagnosed with TB disease or infection, healthy TB-exposed children, and sick children with non-TB lower respiratory tract infection. Serological multiplex assays will be performed to identify M. tuberculosis antigen-specific antibody features, including isotypes, subclasses, Fc receptor (FcR) binding, and IgG glycosylation.

DISCUSSION

The findings from this study will help to design serological assays for diagnosing TB disease in children. Importantly, those assays could easily be developed as low-cost point-of-care tests, thereby offering a potential solution for resource-constrained settings.

CLINICALTRIALS

GOV IDENTIFIER

NCT03044509.

Improved Serodiagnostic Sensitivity of Strip Test for Latent Tuberculosis

INTRODUCTION

Diagnosis of Latent Tuberculosis Infection (LTBI) is difficult due to no clinical manifestations. Cases of LTBI are mostly sputum negative. The World Health Organization recommends the Tuberculin Skin Test (TST) as the current diagnostic standard for LTBI. Our previously developed serologic strip test for LTBI detection had suboptimal sensitivity. Additional Mycobacteriumtuberculosis (MTB) latency-associated antigens may improve the detection rate of LTBI.

AIM

The present study aimed to optimize sensitivity of existing strip test.

MATERIALS AND METHODS

A combination of recombinant latency proteins Rv2029c, Rv2031c, Rv2032, Rv2627c, Rv3133c, and Rv3716c was used to prepare the strips and evaluate the performance with the sera of patients in four well-classified categories: LTBI, active pulmonary TB, healthy TB contacts and other non-TB diseases.

RESULTS

A total of 91 serum samples from various clinical categories were screened with the strips. Among clinically diagnosed LTBI patients, strip test yielded a sensitivity of 75.0%. Among clinically diagnosed non-LTBI subjects, strip test yielded 88.1% specificity. The diagnostic positive and negative predictive values for strip test in reference to various clinical contexts were 77.4% and 86.7%, respectively.

CONCLUSION

Addition of the six potential latency proteins could improve the diagnostic performance of existing strip test for LTBI. The use of suitable immunodominant antigens could maximize sensitivity in the diagnosis and differentiate MTB infection status.