Viral or bacterial infection? New test can tell quickly

"Patients with these symptoms are inappropriately treated with antibiotics far too often due to challenges in discriminating the cause of illness, fueling antibiotic resistance," says Ephraim Tsalik. (Credit: Getty Images)

New testing technology can accurately distinguish between a viral and a bacterial infection for respiratory illness, according to a new study proving feasibility.

The critical difference determines whether antibiotics are warranted. And, importantly, the test may provide results in under an hour.

When patients complain of coughing, runny nose, sneezing, and fever, doctors are often stumped because they have no fundamental tool to identify the source of the respiratory symptoms and guide appropriate treatments. The new technology could solve that problem.

“This is exciting progress,” says study lead Ephraim Tsalik, associate professor in the medicine and molecular genetics and microbiology departments at Duke University School of Medicine.

“We’ve been working on this for over a decade,” Tsalik says. “We knew in 2016 that our test worked in the research setting, but it’s always been our goal to have a test that could produce results rapidly, while patients are at their doctor’s office. It’s important that the distinction can be made quickly to ensure that antibiotics are not inappropriately prescribed.”

The researchers developed a gene expression method that diverges from current diagnostic strategies, which focus on identifying specific pathogens. The current tests are time-consuming and can only identify a pathogen if they specifically target it in the first place.

Host gene expression, however, looks for a distinct immune signal that is unique to the type of infection the body is fighting. The immune system activates one set of genes when fighting bacterial infections and a different set of genes in response to a viral infection.

After the team discovered these gene expression signatures for bacterial and viral infection, they collaborated with BioFire Diagnostics, a company that specializes in molecular diagnostics, to develop this first-of-its kind test.

In a multisite study of more than 600 patients presenting to hospital emergency departments with respiratory infections, the tests identified bacterial infections with 80% accuracy and viral infections with nearly 87% accuracy. The current standard tests have about 69% accuracy. Tests provided results in less than an hour, and two different methods retrospectively confirmed their accuracy.

“Acute respiratory illness is the most common reason that people visit a health care provider when feeling sick,” Tsalik says. “Patients with these symptoms are inappropriately treated with antibiotics far too often due to challenges in discriminating the cause of illness, fueling antibiotic resistance. Our study shows that a rapid test to distinguish between these two sources of illness is possible and could improve clinical care.”

Additional studies are underway to validate this approach in additional groups of patients, Tsalik says. The researchers are also working to adapt the technology to produce more specific information, including whether the virus causing illness is influenza or SARS-CoV-2.

The study appears in the journal Critical Care Medicine,

The National Institute of Allergy and Infectious Diseases of the National Institute of Health supported the work. Among other conflicts listed in the study manuscript, Tsalik and coauthors Ricardo Henao, Micah T. McClain, Geoffrey S. Ginsburg, Thomas W. Burke, and Christopher W. Woods have filed for patents pertaining to the gene signatures; Tsalik, Ginsburg, and Woods are co-founders of Predigen, Inc., to develop the technology.

Source: Duke University