This blood test could fight antibiotic resistance

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Antibiotics are lifesaving drugs, but overuse is leading to one of the world’s most pressing health threats: antibiotic resistance. Researchers are developing a tool to help physicians prescribe antibiotics to patients who really need them—and avoid giving them to individuals who don’t.

Antibiotic resistant bacteria cause at least 2 million infections and 23,000 deaths each year in the United States, according to the Centers for Disease Control. The use of antibiotics is the single most important factor leading to antibiotic resistance around the world.

Scientists identified 11 genetic markers in blood that accurately distinguished between viral and bacterial infections (antibiotics help us fight bacterial infections, but aren’t effective and shouldn’t be used to treat viruses).

The findings, which appear in Scientific Reports, are important because physicians don’t have a good way to confirm bacterial infections like pneumonia and more-often-than-not default to an antibiotic.

“It’s extremely difficult to interpret what’s causing a respiratory tract infection, especially in very ill patients who come to the hospital with a high fever, cough, shortness of breath, and other concerning symptoms,” says Ann R. Falsey, lead study author, professor, and interim chief of the Infectious Diseases Division at UR Medicine’s Strong Memorial Hospital.

“My goal is to develop a tool that physicians can use to rule out a bacterial infection with enough certainty that they are comfortable, and their patients are comfortable, foregoing an antibiotic.”

Unnecessary antibiotics are far from harmless

For the study, researchers recruited a group of 94 adults hospitalized with lower respiratory tract infections. The team gathered clinical data, took blood from each patient, and conducted a battery of microbiologic tests to determine which individuals had a bacterial infection (41 patients) and which had a non-bacterial or viral infection (53 patients).

Thomas J. Mariani, professor of pediatrics and biomedical genetics used complex genetic and statistical analysis to pinpoint markers in the blood that correctly classified the patients with bacterial infections 80 to 90 percent of the time.

“Our genes react differently to a virus than they do to bacteria,” Mariani says. “Rather than trying to detect the specific organism that’s making an individual sick, we’re using genetic data to help us determine what’s affecting the patient and when an antibiotic is appropriate or not.”

The main limitations of the study are the small sample size and that the genetic classifiers selected from the study population may not prove to be universal to all patients, the researchers say.

A patent application has been filed for the method of diagnosing bacterial infection. Edward Walsh, , professor of infectious diseases, and Derick Peterson, professor of biostatics and computational biology contributed to the research.

Source: University of Rochester