Blood Test Quickly Distinguishes Between Viral and Bacterial Infections

A new blood test capable of distinguishing between viral and bacterial respiratory infections could allow for quicker treatment and help curb the overuse of antibiotics.

The test, developed by researchers at Duke Medicine, works by detecting a specific genetic "signature" expressed by a sick person's immune system when responding to a virus.

Published in the journal Science Translational Medicine, the finding paves the way toward faster and more accurate diagnosis and treatment.

"In instances such as pandemic flu or the corona-virus that has erupted in the Middle East, it's extremely important to diagnose a viral illness far more accurately and speedier than can be done using traditional diagnostics," co-senior author Dr. Geoffrey Ginsburg, director of Genomic Medicine and professor of medicine at Duke University School of Medicine, said in a statement. "Current tests require knowledge of the pathogen to confirm infection, because they are strain-specific. But our test could be used right away when a new, unknown pathogen emerges."

A total of 102 individuals were included in the blood test's trial run, which took place in a "real-world" setting at a hospital's emergency department. Of this total number, 28 had a viral infection, 39 a bacterial infection and 35 acted as healthy controls. All told, researchers using the tests accurately classified more than 90 percent of the patients as having a virus or not.

"We were very pleased that the assay could pick out those with viral infection with a high degree of accuracy," said lead author Dr. Aimee Zaas, an associate professor of infectious diseases and international health. "This is perhaps the most important aspect of this effort -- the accuracy of the new test in a real-world setting. It is a major step forward in the test becoming a useful diagnostic to help physicians and patients."

Such accuracy is key in reducing the number of wrongly-prescribed antibiotics -- a subject of growing concern among health officials.

"One of the big global threats at the moment is the emergence of bacterial resistance, and that is largely driven by overuse of antibiotics," said co-senior author Dr. Christopher Woods, an associate professor of medicine, pathology and global health. "This is a growing public health threat, creating infections that are increasingly difficult to manage. A tool that enables us to accurately identify viral infections could curb the indiscriminate use of antibiotics and reduce the development of resistant pathogens."