Other

Bruker Daltonik Gmbh

Bruker Daltonics Gmbh & Co. Kg

Katrin Sparbier

Markus Kostrzewa

Beatrix Wegemann

Christoph Lange

Jochen Franzen

Karsten Michelmann

Ulrich Weller

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

The invention relates to the preparation of biological cells for the mass spectrometric analysis of cellular properties such as taxonomic classification, antibiotic resistances, response to drugs or other active substances, and others. The cells can be prokaryotic or eukaryotic microorganisms which have particularly been cultivated directly on a mass spectrometric sample support, or eukaryotic cells from tissues or cell cultures. The invention proposes that the cells are not disrupted by adding matrix solution for a subsequent ionization by matrix-assisted laser desorption (MALDI), but that they are disrupted in a separate treatment step using acids and/or solvents on the sample support itself. Surprisingly, the cell proteins released then adhere to the sample support so that they can be carefully washed with buffer solution to remove salts and other soluble impurities which can stem from earlier treatment steps, for example from nutrient solution.

Preparation of biological cells on mass spectrometric sample supports for desorbing ionization

The invention relates to methods and instruments for determining the resistances of microbes to antibiotics, in particular those microbes which produce beta-lactamases. The method determines the resistance of the microbes in less than an hour by incubating a tiny quantity of the microbes on a mass spectrometric sample support plate after they have been combined with a dosed quantity of a suitable antibiotic, for example the beta-lactam antibiotic imipenem, and by direct mass spectrometric measurement of the breakdown of the antibiotic by the microbial enzymes.

Rapid test for microbial resistances by mass spectrometry

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 mass-spectrometric method to determine microbial resistances to antibiotics, in which the microbes are cultured in a medium comprising an antibiotic, and a mass spectrum of the microbes is acquired after they have been cultured. The method is characterized by the fact that any microbial growth taking place during the culture is mass-spectrometrically determined with the aid of a reference substance, which is added in a dosed amount and is co-measured in the mass spectrum, wherein a growth in microbes indicates the resistance to the antibiotic.

Mass-spectrometric resistance determination by growth measurement

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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Bremen, Germany

Katrin Sparbier