Volatile biomarkers of Pseudomonas aeruginosa in cystic fibrosis and noncystic fibrosis bronchiectasis.

The purpose of this study was to determine whether volatile organic compounds specific to Pseudomonas aeruginosa could be detected in clinical sputum specimens. Patients were recruited from specialist bronchiectasis and cystic fibrosis clinics. The gold standard for diagnosing Ps. aeruginosa infection was a positive sputum culture. About 72 sputum headspace samples taken from patients at risk of or known to have prior Ps. aeruginosa infection were analysed by solid phase micro-extraction mass spectrometry. 2-nonanone was a marker in Ps. aeruginosa in sputum headspace gas with sensitivity of 72% and specificity of 88%. A combination of volatile compounds, a sputum library of 17 compounds with 2-nonanone, increased sensitivity in the detection of Ps. aeruginosa to 91% with specificity of 88%. In contrast to the 48-hour turnaround for classical microbiological culture, these results were available within 1-2 h. These data demonstrate the potential for rapid and accurate diagnosis of Ps. aeruginosa infection from sputum samples. 2-Nonanone is a compound requiring further study in the exhaled breath as it may improve diagnostic of Ps. aeruginosa infection when combined with other reported volatile markers.