Value of the tuberculin skin testing and of an interferon-gamma release assay in haemodialysis patients after exposure to M. tuberculosis

Background: Interferon-gamma release assay (IGRA) has emerged as a useful tool in identifying latent tuberculosis infection (LTBI). This assay can be performed through testing platforms, such as QuantiFERON-TB Gold Plus (QFT-Plus). This in vitro test has been incorporated by several guidelines worldwide and has recently been considered for the diagnosis of LTBI by the World Health Organization (WHO). The possibility of systematically implementing IGRAs such as QFT-Plus in centers that perform LTBI screening has been accelerated by the decreased availability of tuberculin skin testing (TST) in several countries. Nevertheless, the process to implement IGRA testing in routine clinical care has many gaps. Methods: The study utilized the expertise acquired by the laboratory teams of the Regional Prospective Observational Research in Tuberculosis (RePORT)-Brazil consortium during study protocol implementation of LTBI screening of TB close contacts. Results: RePORT-Brazil includes clinical research sites from Brazilian cities and is the largest multicenter cohort of TB close contacts to date in the country. Operational and logistical challenges faced during IGRA implementation in all four study laboratories are described, as well as the solutions that were developed and led to the successful establishment of IGRA testing in RePORT-Brazil. Conclusions: The problems identified and resolved in this study can assist laboratories implementing IGRAs, in addition to manufacturers of IGRAs providing effective technical support. This will facilitate the implementation of IGRA testing in countries with a high TB burden, such as Brazil.

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Intraocular Tuberculosis: A Challenging Case Mimicking Wet Age-Related Macular Degeneration

Case Reports in Ophthalmology ◽

10.1159/000512578 ◽

2021 ◽

pp. 519-524

Author(s):

Emanuela Interlandi ◽

Francesco Pellegrini ◽

Carlos Pavesio ◽

Marco De Luca ◽

Rocco De Marco ◽

...

Keyword(s):

Macular Degeneration ◽

Skin Testing ◽

Chinese Patient ◽

Age Related Macular Degeneration ◽

Interferon Gamma Release Assay ◽

Tuberculin Skin Testing ◽

Delayed Treatment ◽

Age Related ◽

Release Assay ◽

Systemic Symptoms

An otherwise healthy 72-year-old Chinese patient diagnosed with exudative age-related macular degeneration and decreased vision in left eye was fully investigated. The retrospective analysis of past multimodal imaging revealed bilateral severe choroidal neovascularization and choroiditis associated with a positive tuberculin skin testing and interferon-gamma release assay (QuantiFERON-TB Gold – Cellestis<sup>®</sup>, Chadstone, VIC, Australia) suggestive of latent ocular tuberculosis. The variable presentation and tests’ results interpretation represent the greatest limitations in understanding and treating intraocular TB (IOTB). This may present without any other systemic symptoms, the intraocular tissues are of limited access to biopsies and other tests, including imaging and immunological tests, are of relative value. This case highlights how variable may be the presentation of IOTB, which can be easily misdiagnosed leading to a delayed treatment and worse prognosis.

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Diagnosis and Risk Factors of Latent Tuberculosis Infection among Healthcare Workers Using Whole Blood Human Interferon-gamma Release Assay and Tuberculin Skin Testing

Asian Journal of Research in Infectious Diseases ◽

10.9734/ajrid/2020/v3i330127 ◽

2020 ◽

pp. 15-21

Author(s):

A. N. Umo ◽

O. J. Akinjogunla ◽

N. O. Umoh ◽

G. E. Uzono

Keyword(s):

Risk Factors ◽

Interferon Gamma ◽

Whole Blood ◽

Healthcare Workers ◽

Latent Tuberculosis Infection ◽

Latent Tuberculosis ◽

Tuberculosis Infection ◽

Interferon Gamma Release Assay ◽

Tuberculin Skin Testing ◽

Release Assay

This study established the diagnosis and risk factors of latent tuberculosis infection (LTBI) among health-care workers in an endemic population using Tuberculin skin test (TST) and Quantiferon TB-gold. A total of 609 Healthcare workers from tuberculosis treatment facilities in Akwa Ibom State, Nigeria were studied. The Interferon-gamma release assay was performed using 3ml of whole blood by ELISA according to the manufacturer’s instruction (Cellestis Ltd., Carnegie, Australia) after which 0.1 ml of 5 tuberculin units of Purified Protein Derivative (PPD) was administered intra-dermally to each subject. TST results were read after 72 hours by measuring the size of indurations in millimetres. Data were analysed using SPSS version 17 (SPSS Inc., Chicago, Illinois). At the threshold of 10 mm, the prevalence of LTBI by TST was 45.8% and 24.8% at the IGRA diagnostic value of ≥ 0.351 IU. Laboratory staff and ward orderlies as well as being in service for >10 years, were more significantly associated with LTBI. A moderate agreement of 76.7%, k = 0.51 was obtained between TST at 10 mm, and QFT. Neither previous exposure to TST nor BCG vaccination affected the prevalence of LTBI in the study population. The difference of 54% prevalence of LTBI between TST and QFT may be due to non-tuberculous mycobacterium (NTM) since TST is non-specific. This may have grave implications of drug toxicity and development of resistance to anti-TB drug among individuals harbouring NTM, but receiving anti-TB medication. The 76.7% agreement between the two tests is an indication that the 10 mm cut-off induration for TST is still relevant in the diagnosis of LTBI.

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