Latent Tuberculosis Infection

SPOT the hidden DANGER of latent TB







Active TB vs Latent TB

Of the global population, approximately 2 billion people is estimated to be infected with Mycobacterium tuberculosis1. There are two types of tuberculosis (TB) conditions: active tuberculosis (TB) disease and latent TB infection (LTBI). If untreated, approximately 5%–10% of persons with LTBI may progress to active TB disease, passing the infection to others2 According to the WHO End TB Strategy, systematically providing TB preventive treatment to those at highest risk of developing active TB will prevent the development of disease and reduce the risk of transmission in the population; this is a critical step to End TB.

Latent tuberculosis infection (LTBI) is a state of persistent immune response to stimulation by M. tuberculosis antigens without evidence of clinically manifested active TB3. The immune system cannot eliminate TB bacteria completely instead it is contained in the granuloma. They may develop disease in the future when the immune system weakens, making the person ill and at risk of spreading the infection.






The WHO’s annual report4 on the status of global efforts to End TB notes that, at the present trajectory, most WHO regions and individual countries will fall significantly short of the End TB milestones. Hence, global TB prevention efforts along with targeted testing and treatment of latent TB infection builds a strong core TB infrastructure to realizing TB elimination. For an infection that kills 1.3 million a year, there’s routine screening or a gold standard test for LTBI5 – Either a tuberculin skin test (TST) or interferon-gamma release assay (IGRA) is used. A diagnosis of LTBI first requires that active TB disease be excluded by medical evaluation.

IGRAs are whole-blood tests that measure the individual’s immune reactivity to tuberculosis. Leukocytes from most individual who have been infected with M. tuberculosis will release interferon-gamma (IFN-g) when mixed with antigens derived from M. tuberculosis. To conduct the test, fresh blood samples are extracted and mixed with antigens and controls. Two IGRAs approved by the U.S. Food and Drug Administration (FDA) are6:

  • QuantiFERON® – TB Gold In-Tube test (QFT–GIT);
  • SPOT® TB test (T–SPOT.TB)

The antigens, testing methods, and interpretation criteria for IGRAs differ as below:










The incremental cost-effectiveness of IGRAs and TSTs appears to be influenced mainly by their accuracy. Bacille Calmette-Guérin (BCG) vaccination plays a decisive role in reducing the specificity of TST, leading the choice towards adopting IGRA-only strategies for better diagnostic accuracy.As with TSTs, IGRAs should be used as an aid in diagnosing latent infection with M. tuberculosis. A positive test result suggests that M. tuberculosis infection is likely; negative result suggests that infection is unlikely. An indeterminate result or borderline test result (T-Spot only) indicates an uncertain likelihood of M. tuberculosis infection6.

NOT all IGRAs are the same.

The T-SPOT.TB test is the only globally regulated IGRA that is normalised for both cell number and culture conditions in each patient specimen. The cell enumeration technology in the proprietary T-SPOT.TB test removes serum factors that could adversely affect the test result, making it the most sensitive and most specific test for TB infection7, supported by clinical data obtained even in challenging patient populations.

Learn more about the T-SPOT.TB Test here.



  1. Houben RM, Dodd PJ. The global burden of latent tuberculosis infection: a re-estimation using mathematical modelling. PLoS Med 2016;13:e1002152.
  2. Sutherland I. Recent studies in the epidemiology of tuberculosis, based on the risk of being infected with tubercle bacilli. Adv Tuberc Res 1976;19:1–63.
  3. Latent tuberculosis infection: updated and consolidated guidelines for programmatic management. Geneva: World Health Organization; 2018.
  4. WHO End TB Strategy. World Health Organization. WHO End TB Strategy. Published September 8, 2015. Assessed January 9, 2020.
  5. WHO End TB Strategy. Latent tuberculosis infection Updated and consolidated guidelines for programmatic management. Published 2017, Assessed November 30, 2021 via
  6. Centres for Disease Control and Prevention, Interferon-Gamma Release Assays (IGRAs) – Blood Tests for TB Infection Fact Sheets. Published May 4, 2016. Assessed November 30, 2021 via
  7. Oxford Immunotec. T-SPOT.TB Package Insert PI-TB-IVD-UK V3. Abingdon, UK. February 2019
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Abionic Early Sepsis Detection with Pancreatic Stone Protein (PSP)

Early Sepsis Detection with Pancreatic Stone Protein (PSP)


Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection.

Early recognition of sepsis is essential and is a major determinant of the disease’s outcome, according to The WHO and the Surviving Sepsis Campaign.

However this has proven to be challenging as the confirmation of sepsis diagnosis is based largely on nonspecific clinical signs, laboratory findings and medical scores which are usually obtained after sepsis onset.

Currently, C-reactive protein (CRP) and procalcitonin (PCT) are biomarkers routinely used for patients suspected of sepsis. Pancreatic stone protein or PSP is an emerging biomarker showing promise as it is characterized by higher accuracy in the diagnosis and prognosis of sepsis compared to CRP and PCT.

The Pancreatic Stone Protein (PSP)

• A 16 kDa polypeptide of the C-type lectin family of protein.
• Mostly secreted by the acinar cells of the pancreas but also by the intestine and stomach.
• An early sensor of sepsis and multiple organ dysfunction acting as an “alert signal” to help clinicians provide adequate infection control strategies and organ support to restore homeostasis.


PSP was proven to be more accurate, with a higher sensitivity, specificity, positive and negative predictive values than CRP, PCT, IL-6 and other cytokines for the diagnosis of sepsis and prognosis of unfavourable outcomes in multiple studies and clinical settings (ED, ICU, surgical, nonsurgical adult and children).

It also performed well in studies involving a variety of critically ill patients including severe burns, polytrauma, post-cardiac surgery and on admission to the ICU.

Unique Characteristic

PSP may start to increase above the normal level before the development of clinical signs and symptoms of sepsis.

It was found to be the only biomarker able to identify sepsis 72 hours before clinical diagnosis, thereby providing a large window of opportunity for timely initiation of accurate clinical management.

PSP Measurement

Can now be done via a Point-of-Care(POC) device, which is uncommon for CRP and PCT in ICU, leading the way for simple, on-demand, around-the-clock, serial biomarker assessments instead of one-off testing upon clinical suspicion of sepsis.

This is key to faster treatment decisions, reducing mortality and lowering sepsis-related healthcare costs.

The IVD CAPSULE PSP on the abioSCOPE® is the first CE-marked in vitro diagnostic test to enable fast, reliable and early sepsis detection at the pointof-care from a single drop of blood in only 5 minutes.

Click the link below for more information:

Products | Abionic



Eggimann, Philippe & Que, Yok-Ai & Rebeaud, Fabien. (2019). Measurement of pancreatic stone protein in the identification and management of sepsis. Biomarkers in Medicine. 13. 10.2217/bmm-2018-0194.

Pugin, J., Daix, T., Pagani, JL. et al. Serial measurement of pancreatic stone protein for the early detection of sepsis in intensive care unit patients: a prospective multicentric study. Crit Care 25, 151 (2021).

World Health Organization (WHO). Sepsis.

Rudd KE, Johnson SC, Agesa KM, Shackelford KA, Tsoi D, Kievlan DR, et al. Global, regional, and national sepsis incidence and mortality, 1990-2017: analysis for the Global Burden of Disease Study. Lancet (London, England). 2020;395(10219):200-11.

Klein HJ, Niggemann P, Buehler PK, Lehner F, Schweizer R, Rittirsch D, Fuchs N, Waldner M, Steiger P, Giovanoli P, Reding T, Graf R, Plock JA. Pancreatic Stone Protein Predicts Sepsis in Severely Burned Patients Irrespective of Trauma Severity: A Monocentric Observational Study. Ann Surg. 2021 Dec 1;274(6):e1179-e1186. doi: 10.1097/SLA.0000000000003784. PMID: 31972652.

Keel et al., 2009 and Reding et al., 2018 Pathophysiological mechanisms of PSP function in Sepsis- Abionic slides; Abionic brochure

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