Early release of 1-pyrroline by Pseudomonas aeruginosa cultures discovered using ambient corona discharge ionization mass spectrometry

Abstract

Pseudomonas aeruginosa (PA) is a leading cause of nosocomial infections in humans with an increasing number of health-threatening implications, which urges faster clinical detection of this pathogen. In the present study, we discovered for the first time the early release of 1-pyrroline vapor by PA cultures using direct ambient mass spectrometry (AMS) analysis of the bacterial culture headspace based on corona discharge ionization. Importantly, the concentration of 1-pyrroline in PA cultures was found to greatly increase during the lag phase and early log phase of bacterial growth (3–6 h, 200–800 ppb), enabling early detection. Typically, 1-pyrroline produced by PA cultures could already be detected in our experiments after 0.5–4 h of incubation at the clinically relevant initial bacterial counts. A reference AMS screen of common infectious microbes from other genera, including Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Escherichia coli, Klebsiella pneumonia, Acinetobacter baumannii, Enterococcus faecalis, Klebsiella oxytoca, Candida albicans, Candida tropicalis, Candida parapsilosis, Enterococcus faecalis, Enterobacter cloacae, did not reveal a notable release of 1-pyrroline. Our results indicate the high suitability of volatile 1-pyrroline for the early and reliable diagnosis of Pseudomonas infections using commonly available MS instrumentation.