A simple breath test could be used to diagnose lung infections such as TB by identifying bacterial "fingerprints", scientists have said.
Researchers distinguished between different types and strains of bacteria by testing the breath of mice.
A scaled-up version of the technique could reduce the time it takes to diagnose lung infections in humans from days and weeks to just minutes, it is claimed.
Dr Jane Hill, one of the US scientists from the University of Vermont, said: "Traditional methods employed to diagnose bacterial infections of the lung require the collection of a sample that is then used to grow bacteria.
"The isolated colony of bacteria is then biochemically tested to classify it and to see how resistant it is to antibiotics. 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 team analysed volatile organic compounds (VOCs) given off by two common bugs that infect lungs, Pseudomonas aeruginosa and Staphylococcus aureus. Mice infected with the bacteria had their breath sampled after 24 hours.
The results, published in the Journal of Breath Research, showed statistically significant differences between the breath profiles of infected and uninfected mice.
The test was not only able to tell the species of bacteria apart, but also identify two different strains of one of the bugs.
"I suspect that we will also be able to distinguish between bacterial, viral and fungal infections of the lung," said Dr Hill. "To that end, we are now collaborating with colleagues to sample patients in order to demonstrate the strengths, as well as limitations, of breath analysis more comprehensively."