Researchers working with a mouse model have developed a technique for creating "breathprints" that flag up whether or not the animals have a lung infection.
Using secondary electrospray ionization mass spectrometry (SESI-MS), the team found significant differences in the volatile organic compounds (VOCs) present in the breath of mice that were infected with Pseudomonas aeruginosa or Staphylococcus aureus, compared with the breath of noninfected mice.
Furthermore, the SESI-MS breathprint allowed the researchers not only to detect the species of bacteria but also to distinguish between specific bacterial strains.
"To our knowledge, this is the first report profiling the breath volatiles of mice infected with P. aeruginosa or S. aureus," say Jane Hill (University of Vermont, Burlington, USA) and colleagues. "While there are many studies reporting various bacterial volatile biomarkers or fingerprints using in vitro experiments, it has proven difficult to translate these data to in vivo breath analysis."
However, the identification of bacteria by their volatilomes (the blend of VOCs) in breath is of particular interest to researchers as it has the potential to identify infections in humans.
As reported in the Journal of Breath Research, qualitative analysis of the SESI-MS breathprints showed that P. aeruginosa infections generate different volatilomes to those of S. Aureus infections, and both lung infections have different breathprints compared with uninfected controls.
In addition, the team found that SESI-MS breathprinting provided enough information to differentiate between two strains of P. aeruginosa, PAO1 and FRD1, with one peak identified belonging to PAO1 and nine belonging to FRD1. None of these 10 peaks were produced by S. aureus-infected mice.
"Therefore, for the strains investigated in this study, SESI-MS analysis of the breath of mice can distinguish between infected and uninfected animals, and identify the infectious species to the strain level," writes the team.
"Our in vivo breathprinting study adds to the growing body of literature advancing the promise of successful breath-based diagnostics for infectious diseases," remark the researchers.
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