An in vitro rapid blood assay has been shown to differentiate between bacterial and viral infections with significant sensitivity and specificity, outperforming routine biomarker and laboratory tests. The diagnostic test is described online in the journal PLOS ONE.

Because bacterial and viral infections are often clinically indistinguishable from one another, this can lead to inappropriate use of antibiotics (both overprescribing for viral infections and underprescribing for bacterial ones). The ImmunoXpert diagnostic test extensively screens for immune system proteins in patients with acute infections to identify viral-induced host proteins and bacterial-induced proteins.

In this study, this diagnostic test was utilized on 1,002 pediatric and adult patients with suspected acute infectious disease at varying points following symptom onset and controls with no suspected infection. Three independent physicians assigned a diagnosis based on clinical and laboratory investigation including polymerase chain reaction (PCR) testing for 56 pathogen species and 600 immune system-related proteins. Well-established clinical parameters and laboratory measurements, including white blood count (WBC), absolute neutrophil count (ANC), percentage neutrophils, maximal temperature, pulse, and respiratory rate were compared to the ImmunoXpert assay results.

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The results indicated that the TNF-related apoptosis-inducing ligand (TRAIL) protein was dramatically increased in patients with viral infections but decreased in patients with bacterial infections. Based on these findings, the researchers developed an algorithm to computationally integrate TRAIL with other immune proteins for infection diagnosis. ImmunoXpert had superior performance and accuracy compared to all the comparable well-established clinical parameters and laboratory measurements.

Although C-reactive protein (CRP) testing is routinely used to support diagnosis of bacterial infections, proteins such as TRAIL are not widely used in clinical practice. Future studies should attempt to replicate these results in a diverse population, especially in areas with a high prevalence of endemic chronic pathogens, the authors conclude.

ImmunoXpert is currently approved for clinical use in the European Union and Israel. The company is planning to conduct clinical trials in the U.S. using a specially-designed point-of-care platform in development.

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