Blood test can predict if you need antibiotics

Researchers at Duke University Medical Centre have developed a blood test that can determine whether a respiratory illness is caused by infection from a virus or bacteria so that proper antibiotics can be prescribed.

The team developed what it calls gene signatures - patterns that reflect which of a patient's genes are turned on or off to indicate whether someone is fighting infection from a virus or bacteria.

Results can be derived from a small sample of the patient's blood. The signatures were tested in an observational study described in the journal Science Translational Medicine.

They were found to be 87 percent accurate in classifying more than 300 patients with flu viruses, rhinovirus, several strep bacteria and other common infections, as well as showing when no infection was present.

A respiratory infection is one of the most common reasons people come to the doctor.

“But there's no efficient or highly accurate way to determine whether the infection is bacterial or viral. Most patients end up on antibiotics to treat a bacterial infection despite the fact that the majority have viral infections. There are risks to excess antibiotic use, both to the patient and to public health,” explained," said lead author Ephraim l Tsalik, assistant professor of medicine at Duke.

The new technique is more accurate than other tests that look for the presence of specific microbes, the authors report.

“More precise ways of distinguishing infections could not only reduce unnecessary use of antibiotics, but also lead to more precise treatments of viruses,” added senior author Geoffrey S Ginsburg.

Still, with current technology, measuring a person's gene expression profile from blood could take as long as 10 hours.

The researchers are currently working with developers to create a one-hour test that could be used in clinics.

“Right now, we can give patients Tamiflu to help them recover from an influenza infection, but for most viral infections, the treatment is fluids and rest until it resolves,” Ginsburg noted.

With these findings, Duke researchers are a significant step closer to developing a rapid blood test that could be used in clinics to distinguish bacterial and viral infections and to guide appropriate treatment.