LAUSR

Introduction: Early differentiation of bacterial species is crucial especially in the scope of emerging multiresistant strains. Conventional diagnosis takes about 3 working days even Maldi-TOF requires a preculture and is normally not available in less than 12 – 24 hours. During growth bacteria produce specific volatile compounds (VOC). At the 2014 ERS meeting we could show that these VOC can be detected 2 to 4 hours after incubation in headspace over solid culture but only 4 different bacteria species had been investigated. Methods and materials: In this study patient derived strains of E. coli (5), P. aeruginosa (5), H. influenza (4), Proteus mirabilis (5), MRSA (5), MSSA (5) and Streptococcus pneumoniae- (5) were diluted (McFarlane 0.5), incubated in Brain-Heart-Infusion liquid culture at 37° C for 90-120 minutes and measured as well as non inoculated specimens (7) by MCC-IMS (Fa. Graupner, Geyer). Results: 88 spectra could be derived by cluster analysis. For each species at least one cluster could be found that was significantly increased against all other species and controls. Using this single cluster specifity and sensitivity was calculated as well as for the combination of different clusters: Conclusion: By MCC-IMS a distinction of clinical important bacterial species is possible as early as 90-120 minutes after incubation even for MRSA and MSSA. Investigations with more species and strains are ongoing.