Rapid identification of lung infection by analysing volatile
compounds in breath
16 January 2012
The chemical ‘fingerprints’ given off by specific bacteria
when present in the lungs, can be identified by a type of mass
spectrometry, potentially allowing for a quick and simple breath test to
diagnose infections such as tuberculosis.
The researchers have successfully distinguished between different
types of bacteria, as well as different strains of the same
bacteria, in the lungs of mice by analysing the volatile organic
compounds (VOCs) present in exhaled breath. It is hoped that a
simple breath test could reduce the diagnosis time of lung
infections from days and weeks to just minutes.
Co-author of the paper, publishd in IOP Publishing’s Journal
of Breath Research, Jane Hill, 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”
Clinicians see breath-testing as an attractive method for
diagnosing disease due to its ease of use and non-invasiveness.
Scientists have already investigated breath-based diagnostics for
multiple cancers, asthma and diabetes.
In this study, the researchers, from the University of Vermont,
analysed the VOCs given off by Pseudomonas aeruginosa and
Staphylococcus aureus, both of which are common in acute and chronic
They infected mice with the two bacteria and sampled their breath
after 24 hours. The VOCs were analysed using a technique called
secondary electrospray ionization mass spectrometry (SESI-MS), which
is capable of detecting VOCs down to parts per trillion.
They found a statistically significant difference between the
breath profiles of the mice infected with the bacteria and the mice
that were uninfected. The two different species of bacteria could
also be distinguished to a statistically significant level, as could
the two different strains of the P. aeruginosa that were used.
They hypothesise that bacteria in the lungs produce unique VOCs
that are not found in regular human breath due to their differing
“We have strong evidence that we can distinguish between
bacterial infections of the lung in mice very effectively using the
breathprint SESI-MS approach and I suspect that we will also be able
to distinguish between bacterial, viral and fungal infections of the
“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,” continued
Jiangjiang Zhu et al. Detecting bacterial lung
infections: in vivo evaluation of in vitro volatile fingerprints” J.