Variability in the concentrations of volatile metabolites emitted by genotypically different strains of Pseudomonas aeruginosa

Abstract

To characterize the volatile metabolites produced by genotypically diverse strains of Pseudomonas aeruginosa in order to evaluate their potential for use as biomarkers of lung infection in noninvasive breath analysis. Volatile organic compounds (VOCs) emitted from 36 clinical strains of Ps. aeruginosa (belonging to different multilocus sequence types) cultured in liquid and on solid media were analysed by gas chromatography mass spectrometry (GC-MS) and selected ion flow tube mass spectrometry (SIFT-MS). Several previously identified VOCs were detected, including ethanol, acetone, 2-butanone, 2-pentanone, isoprene, aminoacetophenone, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and methyl thiocyanate. Additionally, significant production of 3-methyl-butanone, acetophenone, methylthioacetate and methyl thiobutanoate was observed for the first time in this study. SIFT-MS quantifications of VOCs showed high variability between genotypically distinct strains. The data obtained indicate that the production rates of the volatile biomarkers of Ps. aeruginosa vary by two orders of magnitude between different strains cultured under the same conditions. Similar variability was observed for both liquid and solid media. Inter-strain genotypic variability strongly influences the concentrations of the volatile biomarkers from Ps. aeruginosa. A group of several biomarkers quantified in real time in exhaled breath may thus provide a more valuable indicator of the course of pulmonary infections compared to a single biomarker.