Novel method of testing exhaled breath to detect infection

Researchers from Johns Hopkins University are developing a novel method of testing exhaled breath to detect infection rapidly after potential exposure to a biological warfare agent. They report their findings today at the 2005 ASM Biodefense Research Meeting.

"We want to have a tool that can help in the emergency room or first responders to triage on site so that people who are infected can get treatment first," says Joany Jackman, a researcher on the project. "It's not so hard to sample breath from many people very quickly as it is to draw blood."

When exposed to disease causing organisms, cells in the body release proteins, called cytokines, to help the immune cells identify and fight the infection. Jackman and her colleagues theorized that cytokines might work their way up through the tissue until eventually they would be exhaled through water vapor in the breath, and could be captured and identified.

"Old medical texts, in the days long before sophisticated diagnostics, would recommend that a doctor check a patient by checking his or her breath, so we knew there must be something to it," says Jackman.

In previous studies, Jackman and her colleagues exposed pigs to different infectious agents and collected breath samples, which they condensed and ran through a mass spectrometer to test for cytokines and other proteins. They were able to detect a strong surge in cytokines in exhaled breath in as little as an hour, long before any visible symptoms appeared.

"However for this technology to be an effective diagnostic, immune markers which appear as a result of exposure to agents should be absent in uninfected populations," says Jackman.

To determine whether the cytokine levels could be differentiated from a healthy population, Jackman and co-investigator Nate Boggs purchased exhaled breath samples from swine housed at a commercial pig farm and analyzed the condensates.

"In all animals, immune markers of infection were at or below the limit of detection, indicating that baseline levels of immune markers in uninfected and apparently healthy populations could be expected to be low or undetectable," says Boggs.

Now that they have shown the concept of exhaled breath diagnostics to be viable, the next step is to move into human testing. Having determined in earlier studies that the early responses of cells to infection vary based on infectious agent, they hope to create cytokine profiles that will help identify specific diseases. They are also working on redesigning the breath collector with an eye towards getting it approved by the Food and Drug Administration.