Establishment and evaluation of a pathogen identification assay based on waste components of MALDI-TOF MS pre-extraction sample preparation

ObjectiveTo improve the pathogen identification power, especially the identification of trace pathogen, of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), a new sample adoption assay was established by using the waste components of its pre-extraction sample preparation.MethodsIn this study, 63 freshly cultured pathogen strains (including 23 strains of bacteria and 40 strains of fungi) were used. After ethanol/formic acid extraction of protein of the pathogen strains, the waste sediment was used to smear the sample target, then the MALDI-TOF MS data collection and analysis were conducted after the combination with the matrix. The identification power for the pathogens was compared with conventional analysis components.ResultsUsing the conventional ethanol/formic acid assay, 50 strains (79.37%) were identified at species level, 10 strains (15.87%) were identified at genus level and 3 strains (4.76%) were not identified. Using precipitation smear assay, 49 strains (77.78%) were identified at species level, 14 strains (22.22%) were identified at genus level. Under the same collection condition, the data collection ability of precipitation smear assay was slightly better than that of conventional assay, and there was no statistical difference in the number of mass spectra peaks obtained by two methods under the same signal-to-noise ratio.ConclusionIn this study, a new pathogen identification assay based on waste components of MALDI-TOF MS pre-extraction sample preparation was established. Two samples can be obtained in one experiment, maximizing the use of sample resources. This method can improve the identification power of MALDI-TOF MS for pathogens, especially for single colony pathogen, providing us a new way for the enhancement of high-throughput and rapid identification of pathogens by mass spectrometry.