We’re all familiar with the concept of a breathalyzer—a device that indicates someone’s blood alcohol content by precisely analyzing his or her breath. Because the breakdown of alcohol produces predictable quantities of various gases, these machines are reliable enough to be used by law enforcement to declare a driver, say, as legally intoxicated.
Recently, a group of researchers from the University of Vermont saw this idea and had another: What if a device could be designed to detect a chemical signature that indicates a bacterial infection in someone’s lungs? Their result, revealed yesterday in the Journal of Breath Research, is a quick and simple breath test—so far used only with mice—that can diagnose infections such as tuberculosis.
In their study, they focused on analyzing volatile organic compounds (VOCs) in mouse breath to distinguish between different strains of bacteria that were infecting the animals’ lungs. They hypothesized that these bacteria produce VOCs not normally present in the lungs, thus allowing their test to differentiate between a healthy animal and a sick one.
Initially, a number of the mice were infected with either Pseudomonas aeruginosa or Staphylococcus aureus—both common types of bacteria in either acute and chronic lung infections—and their breath was tested 24 hours later. The researchers used a technique called “secondary electrospray ionization mass spectrometry” (a name that, admittedly, requires quite a mouthful of expelled air), which can detect VOC quantities of as little as a few parts per trillion.
Their test was a success: There was a significant difference between the chemical signatures of healthy and infected mouse breath, and their test was even able to indicate which type of bacteria were the source of the infection.
Although the concept has only been used on mice so far, the researchers think that you could someday be blowing into a bacterial breathalyzer as part of your routine medical exam. Their prediction stems from the fact that the approach offers several advantages over conventional ways of detecting bacterial infections in the lungs.
“Traditional methods employed to diagnose bacterial infections of the lung require the collection of a sample that is then used to grow bacteria,” said Jane Hill, one of the paper’s co-authors, in a statement. “The isolated colony of bacteria is then biochemically tested to classify it and to see how resistant it is to antibiotics.”
This process can take days and sometimes even weeks just to identify the type of bacteria. By contrast, she said, “Breath analysis would reduce the time-to-diagnosis to just minutes.”
This type of test would also be less invasive than current methods. Thus, for patients suffering from bacterial infections…a breath of fresh air.