New Blood Test Could Reduce Global Antibiotic Use

Scientists at Stanford Medicine have made a new gene expression-based test that could help doctors differentiate between bacterial and viral infections. This could reduce the overuse of antibiotics globally.

Key takeaways:
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    Stanford Medicine researchers created a gene expression-based test to distinguish between bacterial and viral illnesses. This could reduce antibiotic misuse globally.
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    Antibiotic resistance is one of the greatest threats to health, food security, and economic growth worldwide, according to the WHO.
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    Slow bacterial tests and the inappropriate use of antibiotics in otherwise healthy animals contribute to the widespread misuse and overuse of antibiotics.

Published in Cell Report Medicine, this blood test is able to reach up to 90 percent accuracy.

The test, the first to be validated globally, can detect a broader range of bacterial infections than tests that came before it. It is also the first to meet targets set by the WHO to address antibiotic resistance.

The test is one of a new group of diagnostic tests called host-responses that look at how the patient's immune system reacts to determine what type of infection it is.

“The immune system has been doing this for millions of years, constantly learning the bacteria, and viruses, and how to respond to it. Instead of looking for the bug itself, we can ask the immune system,” said Dr. Purvesh Khatri, senior author of the study.

Previous host-response tests didn’t account for developing countries, which leads to specific issues.

"Bacterial infections in developed countries are usually from bacteria that replicate outside the human cell. In developing countries, common bacterial infections like typhus and tuberculosis are caused by intracellular bacteria, which replicate inside human cells, as do viruses."

Dr. Khatri

Current host-response tests can tell the difference between bacterial infections outside of cells with 80 percent accuracy, but they can only tell the difference between 40 and 70 percent of intracellular infections.

The new diagnostic test has a much broader data set from 35 countries. That’s what led to the test’s high 90 percent accuracy rating. It is also a simple blood test that can be performed in 30 to 45 minutes, making it easy to use worldwide.

The WHO says that antibiotic resistance is one of the biggest threats to health, food security, and economic growth worldwide.

Antibiotics are medicines used to stop and treat infections caused by bacteria. When bacteria change because of the use of antibiotics, antibiotics are no longer effective, which is called antibiotic resistance.

“Strong, sustained action across all sectors is vital if we are to turn back the tide of antimicrobial resistance and keep the world safe," said Dr. Tedros Adhanom Ghebreyesus, Director-General of WHO.

Currently, there is a worldwide issue with overusing and misusing antibiotics. Antibiotic resistance happens naturally, but how people and animals use antibiotics speeds up the process.

The slow process of detecting infection in humans is one of the reasons for misuse and overuse. Previous methods for detecting infection could take several days, which is a long time for those who may be infected.

"Accurately diagnosing whether a patient has a bacterial or viral infection is one of the biggest global health challenges. [So] doctors prescribe antibiotics empirically. They say, ‘We’re going to give you an antibiotic and if you get better, you had a bacterial infection. If you don’t, you have a viral infection, and we’ll stop the antibiotic.’"

Dr. Khatri

The Natural Resources Defense Council says that agricultural workers often give healthy animals the same or similar antibiotics that doctors use on people.

In some countries, nearly 80% of all antibiotics are used on animals, primarily to help healthy animals grow faster and larger.

Some bacteria that cause serious infections in humans have already developed resistance to most or all of the available treatments. These bacteria are called “superbugs,” and they can cause illnesses like pneumonia, tuberculosis, and salmonellosis.

Dr. Khatri’s team has applied for a patent on the test and hopes to be able to offer it in both developed and developing countries soon.


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