Breath Test Detects Broad Range of Bacterial Infections Within 10 Minutes

Researchers have developed a breath test that can detect bacterial infections in the lungs, blood, muscles, and bone. In a study published today in ACS Central Science, the test successfully detected the presence of pathogenic bacteria such as E. coli or S. aureus in mice, opening the door for a new generation of fast and affordable infection tests. 

“Accurately and quickly distinguishing invasive bacterial infection from viral illnesses and noninfectious conditions remains a critical challenge in clinical medicine,” writes David M. Wilson, MD, PhD, professor at the department of radiology and biomedical imaging of the University of California, San Francisco. “With the increasing frequency of antibiotic resistance, efficient and non-invasive diagnostic methods are more important than ever.”

Currently, bacterial infections are diagnosed using a variety of tools including blood tests, imaging, cultures, and molecular diagnostics. However, these methods can be slow, non-specific, or expensive, limiting their applicability in routine clinical practice. 

Wilson and colleagues set out to create an affordable and non-invasive test that can give results right away, helping inform immediate treatment decisions. They took inspiration from urea breath tests, which have long been used to diagnose Helicobacter pylori infections. 

These breath tests measure the amount of carbon dioxide produced by H. pylori by administering a liquid that contains urea molecules tagged with carbon-13. In the presence of an infection, the bacteria will metabolize the urea and release the tagged carbon-13 in the form of carbon dioxide, which can be detected in the patient’s breath. 

Based on this concept, the researchers developed a prototype that employed a range of sugars and sugar alcohol compounds tagged with carbon-13, all of which are metabolized by pathogenic bacteria but not human cells. Previous studies using imaging data had shown that healthy bacteria already living in our bodies do not significantly metabolize these compounds when delivered intravenously, while bacteria in actively infected tissues do. 

This approach was then tested in mice with a wide range of bacterial infections, including pneumonia as well as blood, muscle and bone infections. In infected mice, signs of labeled carbon dioxide showed up within the first 10 minutes of administration. In contrast, little to none levels of carbon-13 were found in the breath of healthy mice.

In a mouse model of E. coli infection, the amount of tagged carbon detected in breath decreased over time as the animals received antibiotic treatment. In another mouse model of S. aureus infection, test results correlated with the performance of pathogen-targeted PET tracers used in imaging-based diagnostics. 

While more work will be needed to translate this research into human clinical trials, these findings suggest breath tests could offer a portable, fast alternative to not just diagnose but also monitor the progression of a broad range of bacterial infections. Down the line, the researchers are confident that this method could also be expanded to applications beyond infectious disease. 

“We anticipate that this approach could also be useful in the detection of cancer and other diseases, as a safe and potentially straightforward way to identify metabolic abnormalities,” added Wilson.