Bruker Daltonik Gmbh

Other

Bruker Saxonia Analytik Gmbh

Bruker Daltonics Gmbh & Co. Kg

Markus Kostrzewa

Jochen Franzen

Thomas Maier

Karsten Michelmann

Katrin Sparbier

Ulrich Weller

Wolfgang Pusch

Thomas Wenzel

Stefan Klepel

Christoph Lange

Thomas Fröhlich

Andres Jäschke

Felix Hausch

Thomas Fr&ouml;hlich

The invention relates to the determination of resistances of microorganisms which produce β-lactamases, in particular 'extended spectrum β-lactamases' (ESBL). The invention provides a method whereby the microbial resistance can be measured very simply and quickly by means of the catalytic effect of the microbially produced β-lactamases on β-lactam antibiotics, which consists in a hydrolytic cleavage of the β-lactam ring. The method determines the resistance of the bacteria a few hours after a suitable substrate, either a β-lactam antibiotic or a customized β-lactam derivative, has been added to a suspension of the microbes, by direct mass spectrometric measurement of the substrate breakdown caused by the β-lactamases.

Mass spectrometric measurement of β-lactamase resistances

A method of detecting specified target microbes in different types of sample uses only one to two cultivation steps for the enrichment of the target microbes from the sample, preferably in selective culture media, combined with a mass spectrometric detection method that identifies the target microbes in mixtures with other microbes even if the target microbes account for only a small proportion of the mixture. The sample may be a food sample, a sample from bodies of water used for bathing, a soil sample, a swabbed sample, a stool sample, an impactor sample with collected aerosol particles, amongst many others. The detection method is several days faster than standard methods and less expensive.

Mass spectrophotometric detection of microbes

The invention relates to a mass spectrometric method to determine microbial resistances to antibiotics. The decrease or modification of specific nutrient components by microbes, and thus the metabolism of the microbes, is determined mass spectrometrically in culture media containing antibiotics. Hence it is not the microbes which are introduced into the mass spectrometric analysis, but the culture medium. The special nutrient components which are subject to the mass spectrometric observation are indicators for the metabolism exhibited by the microbes in the culture in the presence of antibiotics, and are thus indicators for their susceptibility or resistance.

Mass spectrometric resistance determination by measuring metabolism

The invention relates to a method for identifying unknown microbes in a sample, wherein a mass spectrometric determination down to the taxonomic level of the genus or species is supplemented by a detailed determination of a lower taxonomic level or variety by means of infrared spectrometry, using restricted reference libraries of infrared spectra. These libraries can be genus-specific, containing only infrared spectra of microbes of one genus, or species-specific, containing only infrared spectra of microbes of one species. In so doing, a robust mass spectrometric identification of the species of unknown microbes is advantageously supplemented with a detailed analysis of the subspecies and varieties by means of infrared spectrometry, primarily in order to identify medically important varieties such as pathovars like EHEC and EPEC, and antibiotic-resistant microbes like MRSA.

Microbe identification by mass spectrometry and infrared spectrometry

The invention relates to methods and instruments for the rapid detection and rapid mass spectrometric identification of microbial infective agents in blood or other body fluids. The invention recognizes that blood is not a good environment for the cultivation of microbes and provides a method which (a) largely destroys or dissolves the human particles in body fluids, such as erythrocytes and leukocytes in blood, without impairing the ability of the microbes to reproduce, (b) separates the microbial pathogens from the fluid, (c) cultivates them in a nutrient broth which contains none of the antimicrobial components of the body fluids, (d) separates them from the nutrient broth, and (e) identifies the microbes by a mass spectrum of the microbial proteins. The dissolution of the human particles also releases the microbes nesting in macrophages. The cultivation in an optically clear nutrient broth with optimum composition not only accelerates the propagation of the microbes compared to all other cultivation methods, but also makes it possible to continuously measure their quantitative growth starting from a low microbe density. This firstly allows the mass spectrometric identification to be carried out at the earliest possible time, secondly provides a positive detection of microbes far ahead of their identification, which can be lifesaving for the patient; and thirdly makes it possible to start the determination of resistances early.

Mass spectrometric diagnosis of sepsis without blood culture

The invention relates to a mass spectrometric method for determining microbial resistances to antibiotics. The invention provides specific methods comprising cultivation in synthetic media, in which several amino acids, preferably only a single amino acid, are isotopically labeled by incorporatingC,N,O orS. If several amino acids are isotopically labeled, they are labeled in such a way that they are each heavier than the corresponding unlabeled amino acids by the same integer mass difference &#x394;m. This ensures that the mass shifts of the peaks always amount to an integer multiple of the mass difference &#x394;m. The total mass difference can be kept relatively small by selecting suitable amino acids. A mass shift of the protein peaks in media with antibiotics indicates that the microbes are resistant. A second embodiment first produces isotopically labeled microbes, which are then tested for their resistance by cultivating them in normal media.

Mass spectrometric determination of microbial resistances

The invention relates to the detection of specified, flagellated bacteria, particularly, in food and stool. A single culturing period of about 12 to 24 hours in a liquid nutrient medium without agitation is combined with a position-selective sampling of the flagellated microbes from the liquid of the culture, after which a mass spectrometric detection method is used which recognizes the target bacteria in mixtures. A second culture step is only necessary in exceptional cases. A species-selective or genus-selective culture medium is advantageous. Positional selection becomes possible because these bacteria use their flagella to counteract sedimentation by chemotaxis, and they collect near the surface. This provides a low-cost detection method that is several days faster than conventional methods

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The invention relates to a method for identifying unknown microbes in a sample, wherein a mass spectrometric determination termination down to the taxonomic level of the genus or species is supplemented by a detailed determination of a lower taxonomic level or variety by means of infrared spectrometry, using restricted reference libraries of infrared spectra. These libraries can be genus-specific, containing only infrared spectra of microbes of one genus, or species-specific, containing only infrared spectra of microbes of one species. In so doing, a robust mass spectrometric identification of the species of unknown microbes is advantageously supplemented with a detailed analysis of the subspecies and varieties by means of infrared spectrometry, primarily in order to identify medically important varieties such as pathovars like EHEC and EPEC, and antibiotic-resistant microbes like MRSA.

The invention concerns the reduction of the risk of an incorrect assignment of samples to sample sites during the manual deposition of samples for ionization by laser desorption (for example MALDI or LDCI). The invention offers a method wherein a sample support with several sample sites is provided, at least one sample site is selected, and the selected sample site is highlighted, at least in contrast to neighboring not selected sample sites, in a way which the human eye can perceive.

Deposition aid for the manual deposition of mass spectrometric samples

Microbes in a sample are identified by calculating similarities between a mass spectrum of the sample and reference mass spectra in a spectral library. The spectral library is divided into a hierarchy of sub-libraries where each sub-library contains reference mass spectra of microbes which are statistically the most prevalent in the samples, but are not included in other sub-libraries and all additional reference mass spectra in the library that have substantial similarity to the reference mass spectra of these microbes. Only if the search in a sub-library does not provide a hit with sufficient certainty of identification, is the search carried out in sub-libraries of higher stages.

Multi-stage search for microbe mass spectra in reference libraries

A dual-stage method is provided for identifying a microbe by, for example, its species or its subspecies. The method includes measuring a mass spectrum of the microbe using a mass spectrometer, calculating indicators for similarities between reference mass spectra in a library and the measured mass spectrum, selecting a group of reference mass spectra similar to the measured mass spectrum, determining a distinguishing weight for each mass signal of the reference mass spectra in the group, where the distinguishing weights emphasize differences between the reference mass spectra in the group, and calculating indicators for similarities between the reference mass spectra in the group and the measured mass spectrum as a function of the distinguishing weights.

Spectrophotometric identification of microbe subspecies

The invention relates to the determination of the nature and strength of enzymatic activity in blood using mass spectrometric measurement of a profile of the reaction products. The determination of the enzymatic activity can be used for medical diagnostics, for example, and also to check the effectiveness of medication. The invention provides a method whereby adding probe substances usually not present in blood offers standardized substrates for measuring the enzymatic activity. The probe substances may be added to whole blood, plasma, or serum. The mass spectrometric measurement of the reaction products, after their reversible immobilization on actively binding surfaces of solids, for example, can deliver biomarker patterns of the reaction products which may be indicators for metabolic anomalies or diseases, since these are often accompanied by the formation or activation of characteristic enzymes.

Mass spectrometric determination of blood enzyme activity

The invention generates mass scale comparability between mass spectra which are acquired in time-of-flight mass spectrometers, particularly with ionization by matrix-assisted laser desorption. Always slightly distorted mass scales of different mass spectra from the same type of sample can be aligned. The flight times of identical ions always differ slightly from one mass spectrum to the next due to non-reproducible processes in the ionization method. Thus the apparent mass values of ion signals of identical substances in different mass spectra do not match even if the flight times are converted into mass values with the identical calibration equation. After alignment of the mass scales, mass spectra can be reliably compared with respect to deviations in intensities of bio-makers, or be added together without deterioration in the mass resolution, and improved reference spectrum libraries can be created. Furthermore, the invention allows more reliable library searches to be carried out.

Mass scale alignment of time-of-flight mass spectra

The invention relates to a method of a mass-spectrometric analysis of known mutation sites in the genome, such as single nucleotide polymorphisms (SNPs), using the method of restricted primer extension. The invention consists of the use of primers with a photocleavable linker. The linker creates a gap in a DNA strand which is almost the same size as a natural DNA building block (nucleoside). The linker forms a bridge over a base pair without inhibiting hybridization or enzymatic extension. However, the linker allows the primers to be cleaved after extension in order to obtain short DNA fragments which can be more easily detected on the mass spectrometer.

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Lilienthal, Germany

Markus Kostrzewa