Rapid evaporative ionization mass spectrometry (REIMS) is a new technique that has been shown to accurately classify yeast and bacteria. Thermal stress is applied onto bacterial colonies which results in evaporation and ionisation of metabolites and structural lipids. The mass spectrometer detects and identifies analytes through spectral database comparison (Strittmatter N, et al. Anal Chem. 2014;86:6555-62). We describe the application of REIMS to cystic fibrosis (CF)-related pathogens and show that the technology can identify P. aeruginosa with 100% accuracy. Differences were observed in the phospholipid and rhamnolipid range; derivatives of quorum sensing molecules (QSM) were also detected. These may provide useful biomarkers for a non-invasive diagnostic tool using ambient mass spectrometric (MS) approaches currently in development.