Shimadzu Corporation

Meijo University

Hiroto Tamura

Teruyo Kato

Keisuke Shima

Naomi Yamamoto

Shinji Funatsu

Koretsugu Ogata

Noriyuki Ojima

Akifumi Hosoda

Yudai Hotta

Yoshihiro Yamada

Yuko Fukuyama

Yosihiro Yamada

Provided is a method of identifying a serovar ofbacteria including a step of subjecting a sample containing microorganisms to mass spectrometry to obtain a mass spectrum, a step of reading a mass-to-charge ratio m/z of a peak derived from a marker protein from the mass spectrum, and an identification step of identifying a serovar ofbacteria in the sample, based on the mass-to-charge ratio m/z, wherein the serovars ofbacteria are classified using cluster analysis using as an index the mass-to-charge ratio m/z derived from at least 12 types of ribosomal proteins S8, L15, L17, L21, L25, S7, SODa, peptidylprolyl isomerase, gns, YibT, YaiA and YciF as the marker proteins.

Microorganism identification method

To provide a method for discriminating a microorganism by selecting and using a marker protein capable of reproducibly and quickly discriminating a bacterial species of the genus. The method for discriminating a microorganism according to the present invention includes: a step of subjecting a sample containing a microorganism to mass spectrometry to obtain a mass spectrum; a reading step of reading a mass-to-charge ratio m/z of a peak derived from a marker protein from the mass spectrum; and a discrimination step of discriminating which bacterial species ofbacteria the microorganism contained in the sample contains based on the mass-to-charge ratio m/z, in which at least one of 17 ribosomal proteins L3, L4, L23, L2, L24, L6, L18, S5, L15, S13, S11, L10, L21, L13, S9, L31, S16 is used as the marker protein and particularly at least one of 8 ribosomal proteins L24, L6, L18, L15, S9, L31, S16 among the 17 ribosomal proteins is used.

Method for discriminating a microorganism

A microorganism identification method according to the present invention includes a step of subjecting a sample containing microorganisms to mass spectrometry to obtain a mass spectrum, a step of reading a mass-to-charge ratio m/z of a peak derived from a marker protein from the mass spectrum, and an identification step of identifying which bacteria of serovar ofgenus bacteria the microorganisms contained in the sample contain, based on the mass-to-charge ratio m/z, in which at least one of two types of ribosomal proteins S8 and Peptidylpropyl isomerase is used as the marker protein.

A sample group forming sectionclassifies samples derived from microorganisms into groups according to empirical information showing the species or strain of each sample. A differential analysis sectionperforms a differential analysis using a peak matrix created based on the result of the grouping. An operator enters group rearrangement conditions concerning the drug resistance of microorganisms. Under the entered conditions, a sample group rearranging/rearrangement-cancelling sectionrearranges the already formed groups by selecting or merging groups using another kind of previously registered empirical information which shows the drug resistance of each group. The differential analysis sectionperforms a differential analysis using a peak matrix newly created based on the result of the rearrangement of the groups. Thus, differential analysis results concerning the resistance to different drugs can be sequentially acquired as the group rearrangement condition is successively changed.

Data analying device and program for data analysis

In a method for analyzing a microorganism using a matrix assisted laser desorption/ionization mass spectrometer, a matrix-and-additive mixture solution prepared by mixing one or both of an alkylphosphonic acid and a surfactant with a matrix substance is used for matrix assisted laser desorption/ionization. Either an alkylphosphonic acid or a surfactant, or both of them are used as matrix additives and are mixed with the matrix substance beforehand to prepare a matrix-and-additive mixture solution. After a solution which contains a microorganism to be analyzed has been dropped onto a sample plate, the matrix-and-additive mixture solution is dropped onto that solution and dried to form a mixed crystal which contains both the constituents of the microorganism and the matrix substance. This crystal is used as a sample for MALDI-MS analysis. The sensitivity of analysis is thereby improved, without increasing the amount of time and labor required for sample preparation.

Method for analyzing microorganisms

To provide a method for discriminating a microorganism including: a step of subjecting a sample containing a microorganism to mass spectrometry to obtain a mass spectrum; a reading step of reading a mass-to-charge ratio m/z of a peak derived from a marker protein from the mass spectrum; and a discrimination step of discriminating which bacterial species ofbacteria, andthe microorganism contained in the sample contains based on the mass-to-charge ratio m/z, in which at least one of 13 ribosomal proteins S5, L15, S13, L31, L22, L19, L20, L13, S15, L25, HNS, HdeB, and L29 is used as the marker protein.

Method for discriminating microorganism

A microorganism identification method includes steps of: obtaining a mass spectrum through mass spectrometry of a sample including microorganisms; reading, from the mass spectrum, a mass-to-charge ratio m/z of a peak associated with a marker protein; and identifying which bacterial species of the genusare included in the microorganisms in the sample based on the mass-to-charge ratio m/z. The microorganism identification method is further characterized in that at least one of the following 18 marker proteins is used as the marker protein, S10, L23, S19, L22, L16, L29, S17, L14, L24, S14, L18, L15, L36, S13, S11 (Me), L32, and L7/L12.

An apparatus that identifies the type of a test cell based on a result obtained by performing mass spectrometry on the test cell includes a higher-level database, which contains mass lists that each list ion mass values of constituent components of a known cell, and a lower-level database, which contains partial mass lists that each list only strain-specific ion mass values out of the ion mass values. The higher-level database is first searched for a test mass list which is created from the result of the mass spectrometry performed on the test cell, and based on a result of the search, an organism species to be searched in the following search operation is determined. Mass values common to the organism species are subsequently deleted from the mass list for the test cell, and the mass list having undergone the deletion operation is used to search the lower-level database.

Cell identification device and program

[Problem to be Solved] To select a marker peak which characterizes a difference between groups, even when the number of samples belonging to each group is small. [Solution] A peak matrix is created based on the peaks detected from mass spectra of a plurality of samples belonging to a plurality of groups (S-S). Each row of the peak matrix represents a peak-intensity distribution for a large number of samples at one mass-to-charge-ratio value. If there is no difference between the groups at a certain mass-to-charge-ratio value, the peak-intensity distribution at that mass-to-charge-ratio value should be a lognormal distribution (or normal distribution). Accordingly, a hypothesis test for the conformity of the peak-intensity distribution to the lognormal distribution is performed for each mass-to-charge-ratio value (S). A mass-to-charge-ratio value at which a significant difference has been found is selected as a candidate of the marker peak (S).

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Kani, Japan

Hiroto Tamura