New Assay Can Distinguish Between Viral and Bacterial Infections in Kids Interview with:
Prof. Alain Gervaix
Head of the Emergency Division
Department of Children and Adolescents
University Hospitals of Geneva
Switzerland What is the background for this study?

Response: Many are familiar with the following ‘seemingly’ simple clinical dilemma that occurs on a daily basis across the world. A patient visits the doctor with a fever. Commonly, assigning a diagnosis comes down to deciding whether the infection is bacterial or viral. Accordingly, the doctor decides if to treat or not to treat with antibiotics. The problem is that bacterial and viral infections often present with very similar symptoms, causing uncertainty that leads to antibiotics being used, in many instances, when they are not needed. This antibiotic misuse contributes to the rise of antimicrobial resistance, one of the biggest health threats of the 21st century.

Host biomarkers hold great promise as routine diagnostic tools that can assist doctors in making correct antibiotic treatment decisions, as they overcome key limitations of currently applied pathogen-based tests. Recently, a novel host-assay (ImmunoXpert™) for differentiating bacterial from viral infections was developed and validated to yield high sensitivity and specificity. The three-protein host-assay comprises tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), Interferon gamma-induced protein-10 (IP-10) and C-reactive protein (CRP). What are the main findings?

Response: We wanted to conduct a study to validate the diagnostic performance of this new test in children. PATHFINDER is an international, multi-center, external double-blinded, clinical study that evaluated the ImmunoXpert™ test in pediatric population (aged ≥3 months to ≤18 years). The study enrolled 597 patients with suspected acute infection including fever without identifiable source, upper and lower respiratory tract infections, urine tract infections, and non-infectious controls. Patient samples were collected from five pediatric emergency departments and two pediatric wards in Switzerland and Israel.

The study demonstrated that the new assay accurately distinguished between bacterial and viral patients with 94% sensitivity and 90% specificity, and a negative predictive value of 98%.  Subgroup analysis supports that the assay exhibits consistent performance across a wide range of ages, time from symptom onset, and clinical syndromes. Moreover, the assay outperformed routine laboratory parameters used to manage patients with infections, including white blood count, C-reactive protein and procalcitonin. What should clinicians and patients take away from your report?

Response: Well overall, this study supports that the ImmunoXpert™ test can help doctors with the seemingly simple clinical dilemma mentioned before, namely decide if an infection is bacterial or viral. Specifically, the Pathfinder study is the first double-blind, investigator-driven validation study in febrile children ≥3 months and ≤18 years old of a novel assay comprising the host-proteins (TRAIL, IP-10 and CRP) for distinguishing between bacterial and viral etiologies. The assay was found to be highly accurate and compared to routine care it significantly reduced both false negatives, potentially reducing missed bacterial infections, and false positives, potentially reducing antibiotic overuse. A key strength of this study is the double-blinded design, as this ensured that the principle investigator and the expert panel were not influenced by the assay result and that the assay performer was not biased by the reference standard diagnosis. This type of strict study design is rarely applied in our field, and increases confidence in the results. What recommendations do you have for future research as a result of this study?

Response: ImmunoXpert™ is a simple blood test that is cleared for clinical use in the EU (CE-IVD certified), Switzerland and Israel, and is currently in pilot distribution in these territories. The first generation of the test has a two-hour analytical time and requires a trained laboratory technician, which precludes its wide use in the outpatient setting where much antibiotic overuse occurs. A rapid (within minutes) and easy to use format of the assay for the ED and point-of-care is needed, and currently in final stages of development. Future studies will need to evaluate the point-of-care test in real clinical settings. Additionally, future studies should seek to replicate the results in other pediatric populations, including the developing world, where there isneed for reliable tests to aid in the diagnosis of pediatric non-malarial febrile illness, particularly tests that take into account different co-morbidities, such as malnutrition Thank you for your contribution to the community.


Pediatrics September 2017
Validation of a Novel Assay to Distinguish Bacterial and Viral Infections

Isaac Srugo, Adi Klein, Michal Stein, Orit Golan-Shany, Nogah Kerem, Irina Chistyakov, Jacob Genizi, Oded Glazer, Liat Yaniv, Alina German, Dan Miron, Yael Shachor-Meyouhas, Ellen Bamberger, Kfir Oved, Tanya M. Gottlieb, Roy Navon, Meital Paz, Liat Etshtein, Olga Boico, Gali Kronenfeld, Eran Eden, Robert Cohen, Helène Chappuy, François Angoulvant, Laurence Lacroix, Alain Gervaix

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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