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Blood Test May Lower Antibiotic Use

Could Help Decrease Spread of Antibiotic Resistance

WebMD Health News

Feb. 18, 2004 -- Currently, some doctors prescribe antibiotics for respiratory infection knowing good and well that they won't help in many cases. That's because doctors have no good way of telling who would benefit from such treatment. But now a new blood test promises to one day make that decision much easier -- and more accurate.

Researchers say that as many as 75% of antibiotics prescriptions for respiratory infections are unnecessary because these infections are caused by viruses. Antibiotics commonly used to treat such infections only fight bacteria -- not viruses.

This inappropriate use of antibiotics is believed to be a main cause for the spread of antibiotic-resistant bacteria, say Swiss researcher Beat Muller and colleagues. The problem is that doctors have no good way of telling if someone has a bacterial or a viral infection.

But in a new study, the researchers found that identifying bacterial infections with a quick blood test could cut antibiotic prescriptions in half. The study is published in the Feb. 21 issue of The Lancet.

Muller and colleagues studied 243 patients admitted to the hospital with a suspected lower respiratory infection, such as pneumonia or bronchitis. Half of the participants were treated with standard care -- relying on the doctor's diagnosis to determine antibiotic use -- while the other half received the blood test to help determine the need for antibiotics.

The test looks for high levels of a chemical called procalcitonin in the blood. Levels of this chemical are high in people with a bacterial infection but low in those with a viral infection.

Antibiotic prescriptions were cut in half among the blood test group -- without increasing the number of deaths or worsening illness. Both groups had similar outcomes -- four deaths in each group. Delayed or withheld antibiotics did not cause any of the deaths in the blood test group, researchers say.

Although the blood test is not yet widely available, the researchers say that their finding could one day help significantly lower the use of inappropriate antibiotics -- and thus hopefully slow the development of more antibiotic resistance.

SOURCE: Christ-Crain, M. The Lancet, Feb. 21, 2004; vol 363: pp 600-607.