Innovative Breath Test Offers New Hope for Bacterial Infection Diagnosis

A groundbreaking non-invasive breath analysis has been developed, showing significant potential for the rapid diagnosis and monitoring of bacterial infections. This innovative test, created by researchers at the University of California, San Francisco (UCSF) in collaboration with St. Jude Children's Research Hospital, utilizes pathogen-specific metabolic tracers along with a laser-based detection system to identify infections in real time.

During a presentation at the ESCMID Global 2025 conference, lead researcher Dr. Marina Lopez-Alvarez outlined the promising results obtained from preclinical models, emphasizing the test's feasibility for future clinical use.

The breath test operates on the principle that pathogenic bacteria metabolize certain enriched compounds, producing detectable levels of [13C]CO2 in exhaled breath, unlike mammalian cells. The research team focused on five bacterial species: Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Enterococcus faecalis, and Enterobacter cloacae. They discovered that these bacteria metabolized specific 13C-enriched compounds, including 13C-maltose and 13C-mannitol, while others like 13C-glucose and 13C-sorbitol were also metabolized by mammalian cells, making them less effective for infection detection.

To validate their approach, infected mice models were administered 13C-maltose and 13C-mannitol, and their exhaled breath was analyzed for [13C]CO2. The results showed that healthy mice did not produce [13C]CO2 after ingestion of these substances, confirming their specificity for bacterial metabolism. This specificity is crucial, especially in cases where traditional imaging tools might reflect the host's immune response rather than directly identifying the pathogens.

Dr. Lopez-Alvarez pointed out that this innovative method allows for rapid and accurate detection of infections, which is particularly important given the challenges posed by sterile inflammatory diseases that can lead to misdiagnosis.

Additionally, the research demonstrated that E. coli-infected mice treated with the antibiotic ceftriaxone showed a marked decrease in [13C]CO2 levels, indicating a reduced bacterial presence. This suggests that the breath test could serve not only for diagnosing infections but also for monitoring the effectiveness of antibiotic therapies in real-time.

While the study did not directly assess the sensitivity of the detection method, previous research indicates that the laser-based approach offers cost and portability benefits compared to conventional isotope ratio mass spectrometry (IRMS) methods. Professor David M. Wilson, a principal investigator in the study, noted that the integrated cavity output spectroscopy (ICOS) system is both affordable and compact, making it feasible for use in emergency rooms and other acute care settings.

Before clinical testing on patients suspected of bacterial infections can commence, researchers must first confirm that healthy humans do not produce [13C]CO2 from these metabolites, a critical step to ensure the test's reliability in clinical environments.

While breath tests are currently employed to diagnose Helicobacter pylori infections, there is an intention to broaden this diagnostic technique for a wider range of bacterial infections. Dr. Lopez-Alvarez concluded that this research represents a significant advancement towards non-invasive and rapid infection detection, which could have profound implications in emergency medicine, intensive care, and antimicrobial stewardship initiatives.