Profiles of volatile indole emitted by Escherichia coli based on CDI-MS

Escherichia coli is an important pathogen of nosocomial infection in clinical research, Thus, exploring new methods for the rapid detection of this pathogen is urgent. We reported the early release of molecular volatile indole vapour of E. coli cultures and blood cultures analyzed by direct atmospheric corona discharge ionization mass spectrometry (CDI-MS). The concentration of indole in E. coli cultures remarkably increases during the early log and lag phases of bacterial growth, thereby enabling early detection. Technical replicates were cultivated for 3 days for reference diagnosis using current conventional bacteraemia detection. A reference MS screen of common microbes from other genera confirmed that the peaks at m/z 116 signal corresponded to indole were specifically present in E. coli. Our results indicated that volatile indole based on CDI-MS without the need for any sample pretreatment is highly suitable for the reliable and cost-efficient differentiation of E. coli, especially for bacteraemia in humans.