Bacterial and viral infections are often clinically indistinguishable, leading to antibiotic overuse and contributing to the spread of antibiotic resistance, which the World Health Organization says is approaching crisis proportions. "The incorporation of novel viral-induced proteins, currently not in clinical use, enables ImmunoXpert to attain high levels of accuracy, which can help physicians make better informed antibiotic treatment decisions. The assay was validated in a diverse group of pediatric and adult patients at different time points after the onset of symptoms (from the first day up to 12 days) and across 56 different pathogen species. The accurate differential diagnosis provided by this novel combination of viral- and bacterial-induced proteins has the potential to improve management of patients with acute infections and reduce antibiotic misuse. For the past four years, our team has been collaborating with leading clinicians and scientists from around the world to develop and validate our novel approach for distinguishing between bacterial and viral infections. https://doi.org/10.1371/journal.pone.0120012 Academic Editor: Oliver Schildgen, Kliniken der Stadt Köln gGmbH, GERMANY Received: December 2, 2014; Accepted: February 2, 2015; Published: March 18, 2015 Copyright: © 2015 Oved et al. Funding: This study was funded by MeMed. ### 
 
 About MeMed 
 
 MeMed is dedicated to improving patient lives through research, development and commercialization of pioneering products that monitor the body's immune state. Paradoxically, the inability to rapidly differentiate infections also results in the underuse of antibiotics, estimated to occur in 20-40% of all bacterial infections, putting patients at risk of complications and increasing healthcare costs. MeMed researchers developed the ImmunoXpert test to accurately distinguish between bacterial and viral infections, with the goal of improving patient management by providing physicians with information that enables them to reduce both the overuse and underuse of antibiotics. These include: (i) pathogen detection in cases where the infection site is not readily accessible (e.g., pneumonia), or is unknown (e.g., fever without source); (ii) time to microbiological laboratory results may be lengthy (hours or days); (iii) interpreting whether a detected bacteria is the disease causing agent or a mere colonizer [12–14], and (iv) identification of a virus does not preclude the possibility that an undetected bacteria may be the cause of the underlying illness (i.e. By conducting extensive screening of immune system proteins in patients with acute infections, researchers identified three soluble proteins that are uniquely activated by bacteria or viruses. Unlike most infectious disease diagnostics that rely on direct pathogen detection, MeMed's assay decodes the body's immune response to accurately characterize the cause of the infection. Study population Pediatric patients (≤18 years) were recruited from pediatric emergency departments, pediatric wards and surgical departments, and adults (>18 years) from emergency departments, internal medicine departments and surgical departments. The signature is amenable to rapid measurement using a blood test run on standard hospital and laboratory-deployed automated platforms, or using a point-of-care device now in development. Bioinformatics analysis was then used to identify a combination of three proteins with complementary dynamics: (i) We found that TRAIL was induced in response to a wide range of viral infections and surprisingly, also exhibited significantly reduced levels in bacterial infected patients (Fig. Despite advances in infectious disease diagnosis, timely identification of bacterial infections remains challenging, leading to antibiotic misuse with its profound health and economic consequences.
– When you're hacking up a lung and it's not getting better, you know you're going to have to visit the doctor. What you (and even the doctor) often don't know is whether that antibiotic Rx you may get is going to work, simply because it's often hard to tell the difference between a viral and bacterial infection. But a study published in PLOS One says that may all change with a blood test that can quickly differentiate between the two, the BBC reports. And if MeMed's ImmunoXpert proves to work as scientists say it does, it could not only get antibiotics more quickly to patients with bacterial infections (the only ones antibiotics work on), but also cut down on patients who don't have bacterial infections from taking them. That's big, because overuse is linked to widespread antibiotic resistance. The study in Israel examined some 1,000 patients, scrutinizing the body's immune response to the sickness and honing in on protein trails that are activated depending on whether an infection is viral or bacterial. In particular, levels in blood of one protein called TRAIL significantly shot up in subjects who had been infected with viruses, while it dropped in patients with bacterial illnesses. The CEO of MeMed says the test works—a post at EurekAlert touts "highly accurate results, with sensitivity and specificity greater than 90%"—and offers results within two hours for most patients, per the BBC. "It is not perfect and it does not replace a physician's judgment, but it is better than many of the routine tests used in practice today," Eran Eden says. (A newly discovered antiobiotic may help fight superbugs.)