Viral or Bacterial?

A blood test developed by researchers at Duke University can predict with tremendous accuracy whether someone with, say, pneumonia has a viral or bacterial infection, even if it's a previously unknown strain.

The test, described today in the journal Science Translational Medicine, could someday help stop the unnecessary prescribing of antibiotics to patients who have viral infections.

Although the study's authors say the timing of their report is coincidental, on Monday the director of the U.S. Centers for Disease Control and Prevention (CDC) told reporters that something must be done to curtail the inappropriate use of antibiotics. The practice has led to emerging bacterial strains that are resistant to all known drugs.

“The timing of the CDC report regarding the overuse of antibiotics and our results is really amazing,” said Dr. Christopher Woods, an infectious disease researcher at the Institute for Genome Sciences at Duke's School of Medicine in Durham, N.C.

The CDC director announced that 23,000 Americans per year die of antibiotic-resistant bacterial infections. “That's a small drop compared to what happens globally,” Woods said.

How the Test Works

The Duke test can recognize a specific genetic fingerprint that the body expresses when it's sick.

In the most recent experiment, 102 subjects with viral and bacterial infections, as well as healthy control patients, arrived at a hospital emergency room and were given the blood test. With about 90 percent accuracy, the test returned the proper diagnosis in just 12 hours.

Dr. Geoffrey S. Ginsburg, also of Duke's Genome Institute, told Healthline that the test results were confirmed using traditional lab tests, which take much longer and are far more labor-intensive. “It was really outstanding from our perspective having an assay [test] that performed so robustly in a real-world setting.”

In larger studies set to begin as early as this flu season, scientists will look at ways of paring down the number of genes the test analyzes and reducing the test's turnaround time to as little as one hour. “We'd love to have the pregnancy test equivalent to viral infections,” Ginsburg said.

Stamping Out a Bioterrorism Threat

Woods, Ginsburg, and others have filed for a provisional patent on the science behind the test. Their experiment was funded in part by the Defense Advance Research Project Agency (DARPA), an arm of the U.S. Department of Defense.

Many of the infectious samples the team used to develop the test came from the global H1N1 pandemic of 2009. Many H1N1 sufferers were not quickly diagnosed and treated, which allowed the disease to spread to even more individuals.

In addition to the early detection of naturally occurring global pandemics, the authors believe their test could also help the U.S. respond to a bioterrorism attack. “This could help screen people for exposure, perhaps even before they have fully developed symptoms,” Ginsburg said. “We hope it's an application, if it ever comes to that.”

Ginsburg said he expects medical technology companies will follow suit to develop smaller, more readily available diagnostic equipment for rapidly analyzing test samples. “Our hope is it could shut a pandemic down before it gets started,” he said.

The most immediate application, however, will be to curb the overuse of antibiotics. Patients often arrive at the doctor's office with a common cold, which is caused by a virus. Because the symptoms could falsely point to a bacterial infection, antibiotics are often prescribed.

Not only is the treatment futile, it lets bacteria learn to mutate and become more powerful, Ginsburg said, and wastes a patient's time and money.

In a brief statement to Healthline, the CDC said, “CDC welcomes new strategies and technologies that seek to curb unnecessary antibiotic use and resistance.”

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