The researchers, from the University of Vermont in the US, write about their findings in the 10 January issue of the online Journal of Breath Research.
The study was conducted on mice, but if it can be repeated in humans, then the hope is that a simple breath test could reduce the time taken to diagnose lung infections from days and weeks to minutes.
Another advantage of the breath-test method over the current alternative is that it is easy to administer and non-invasive.
Current Diagnosis Of Lung Infection Is Lengthy and LaboriousCurrently, correct diagnosis of bacterial lung infection requires taking a sample, growing a colony of bacteria from it in a lab, then doing biochemical tests to find out the class of bacteria and which antibiotics it is resistant to.
Co-author Jane Hill says in a press statement:
"This whole process can take days for some of the common bacteria and even weeks for the causative agent for tuberculosis. Breath analysis would reduce the time-to-diagnosis to just minutes."
The StudyFor their study, Hill and colleagues infected mice with two bacteria that are common in acute and chronic lung infections, Pseudomonas aeruginosa and Staphylococcus aureus, and then tested their breath after 24 hours. They also tested the breath of a second group of uninfected mice for comparison.
The method they used to test for volatile organic compounds is called secondary electrospray ionization mass spectrometry (SESI-MS). The technique can find minute traces of such compounds, down to one part per trillion.
When they analyzed the results, the researchers found a statistically significant difference in the chemical breath profiles of the infected and uninfected mice.
The team was also able to identify the two species of bacteria, to a level that was statistically significant. The researchers could even distinguish between the two strains of P. aeruginosa they used.
Strong EvidenceHill says the study provides strong evidence that it is possible to use SESI-MS breathprints to distinguish among different bacterial infections in mice, and it is very likely the same method would be able to identify bacterial, viral and fungal infections of the lung.
She and her colleagues propose that as in mice, when bacteria infect the lungs of humans, they produce unique volatile organic compounds that are not present in exhaled breath of uninfected people, due to their different metabolism.
The team is now collaborating with others to test their new approach on samples taken from human patients. Breath tests are already being investigated to diagnose cancer, asthma, diabetes and other diseases.
In October 2011, scientists reported developing a breath test based on a sensor array that can diagnose multiple sclerosis (MS), the most common neurological disease in young adults.