Rapid Pathogen Identification Based On MS Analysis Of VOCs Fingerprints

Objective:The investigation on volatile organic compounds of common pathogens by mass spectrometry analysis for the clinical value of bacterial identification.Methods:BACT/ALERT 3D automated blood cultures instrument enriched the bacteria.Identified by VITEK2-compact automated microbial analyze. VOCs of solid cultures and blood culture were detected by SDAPCI-MS. The differences and similarities of fingerprint were assessed by principal component analysis(PCA).Results:The ion chromatograms were acquired by two ion detection mode(SDAPCI+/-)screen of eight microbial cultures corresponding to five bacterial and three fungal species, the mass spectrum of microbial VOCs on solid medium different between each other different strains can be distinguished by visual inspection. PCA can accurately distinguish the clinical common eight pathogens, Gram-negative bacteria clustered relatively, and were separated far away from candida, the replicates of Staphylococcus aureus were clustered at the largest distance from the rest of bacterial.Preliminary screening the specific biomarker signals of various pathogen, such as m/z116(indole)、m/z70(pyrroline) and m/z140(nitrophenol) signals were specifically present in Escherichia coli 、 Pseudomonas aeruginosa and Candida,m/z87(isobutyric acid) and m/z101(isovaleric acid) signals were specifically present in Staphylococci. m/z60(trimethylamine) 、 m/z88(dimethyl acetamide) and m/z64(nitric acid)、m/z76(glycine) signals of AB and KP were obvious. the specific VOCs of bacteremia blood cultures were consistent with corresponding strain cultured on solid medium, blood culture of 4 gram-positive Staphylococci significantly different from each other in PCA.Conclusion:VOCs are useful microbial biomarkers, the first application of VOCs successfully identify clinical common pathogens: pyrroline and nitrophenol were first discovered specifically exists in PA and Candida; isovaleric acid 、isobutyric acid and indole were discovered specifically exists in SA and EC; trimethylamine and dimethyl acetamide signals of AB as well as nitric acid and glycine signals of KP were obvious. Identification of bacteria by SDAPCI-MS method is fast, easy operation and repeatable high, further the results were reliable, particularly suitable for the detection of VOCs. rapid pathogen identification based on mass spectrometry analysis of VOCs fingerprints can be well applied to the diagnosis of bacterial infectious diseases.