Microbial test standard for use in infrared spectrometry
The invention relates to a microbial test standard for use in infrared spectrometry which has at least two resealable vessels which are liquid-tight when closed, each of which contains a predefined amount of dried biomass of a microorganism. The microorganisms in the different vessels differ in at least one characteristic, which is selected in particular from the group comprising species, subspecies, strain, serovar, pathovar, toxivar and variety, and the difference manifests itself in a predefined intermicrobial spectral distance. The disclosure furthermore comprises a method of using the microbial test standard.
1. An infrared (IR) spectrometry system for acquiring IR spectra of unknown microbe samples, the system comprising:
an IR spectrometer;
a sample support on which the unknown microbe samples are located at respective sample sites; and
a microbial test standard comprising a predefined amount of a first reference microorganism and a predefined amount of a second reference microorganism, IR spectra of said first and second reference microorganisms having respective first and second spectral signatures that, when acquired with the IR spectrometer under reliable measurement conditions, are separated by a spectral distance greater than a predetermined minimum spectral distance, and that, when acquired with the IR spectrometer under unreliable measurement conditions, are not separated by a spectral distance greater than said predetermined minimum spectral distance,
said first and second reference microorganisms being applicable to sample sites on the sample support to allow acquisition of IR spectra of the first and second reference microorganisms and IR spectra of the unknown microbe samples under similar measurement conditions, which are deemed reliable for identification of the unknown microbe samples if the first and second spectral signatures in the acquired IR spectra of the first and second reference microorganisms are separated by a spectral distance greater than said predetermined minimum spectral distance.
2. The system according to claim 1 , wherein the first and second reference microorganisms differ in at least one of their characteristics selected from the group: species, subspecies, strain, serovar, pathovar, toxivar and variety.
3. The system according to claim 1 , wherein the first and second reference microorganisms belong to different respective strains of one bacterial species.
4. The system according to claim 1 , wherein an identity and/or a specific property of at least one of the reference microorganisms is known.
5. The system according to claim 1 , wherein the reference microorganisms of the microbial test standard are in the form of dried biomasses.
6. The system according to claim 5 , wherein the dried biomasses are sterilized.
7. The system according to claim 5 , wherein the dried biomasses comprise vacuum-dried pellets.
8. The system according to claim 1 , further comprising a first resealable vessel that contains the first reference microorganism, and second resealable vessel that contains the second reference microorganism.
9. The system according to claim 8 , wherein the vessels comprise screw caps.
10. In an infrared (IR) spectrometry system for acquiring IR spectra of unknown microbe samples, the system having an IR spectrometer and a sample support on which the unknown microbe samples are located at respective sample sites, a microbial test standard comprising:
a predefined amount of a dried biomass of a first reference microorganism contained within a first resealable vessel, an IR spectrum of the first reference microorganism having a first predetermined spectral signature; and
a predefined amount of a dried biomass of a second reference microorganism contained within a second resealable vessel, an IR spectrum of the second reference microorganism having a second predetermined spectral signature;
wherein said first and second reference microorganisms are selected such that, when IR spectra of the first and second reference microorganisms are acquired with the IR spectrometer under reliable measurement conditions, the first and second predetermined spectral signatures are separated by a spectral distance greater than a predetermined minimum spectral distance, and when IR spectra of the first and second reference microorganisms are acquired with the IF spectrometer under unreliable measurement conditions, the first and second predetermined spectral signatures are not separated by a spectral distance greater than a predetermined minimum spectral distance; and
wherein said first and second reference microorganisms are applicable to sample sites on the sample support to allow acquisition of IR spectra of the first and second reference microorganisms and IR spectra of the unknown microbe samples under similar measurement conditions, said measurement conditions being deemed reliable for identification of the unknown microbe samples if the first and second spectral signatures in the acquired IR spectra of the first and second reference microorganisms are separated by a spectral distance greater than said predetermined minimum spectral distance.