Kit and methods for the rapid detection of the absence or presence of a β-lactamase in samples of body fluids
The present invention concerns a kit and methods for the detection of absence or presence of a β-lactamase, for example a penicillinase, in a sample comprising or derived from a body fluid taken from a patient suffering from an infection. In some embodiments, the goal of the invention is to rapidly identify infections which can be treated effectively with a penicillin compound. The invention contributes to slowing down the occurrence of resistances to last generation antibiotics. This is achieved by using penicillin compounds for treating infections whenever this can be done efficiently. In brief, the present invention provides a tool for maximizing the use and efficiency of penicillin antibiotics. In other embodiments, the test kit of the invention can be used to detect cephalosporinases (including ESBLs) or carbapenemases.
1. A method for detecting the presence of a β-lactamase in a sample comprising or derived from a body fluid taken from a patient suffering from an infection, the method comprising:
providing a filter system comprising a recipient comprising a filter at or in vicinity of the bottom of the recipient, wherein the filter system is adapted to receive said sample and to retain bacteria and/or bacterial proteins contained in the sample, wherein said filter system is adapted to centrifugation;
providing a tube adapted to centrifugation, said tube being adapted to receive said recipient and to collect a filtrate from said filter system during centrifugation;
loading the sample onto the recipient comprising said filter;
centrifuging said filter system comprising said tube, said recipient, and said sample and filtering said sample;
exposing bacteria in said recipient to a surfactant solution;
exposing bacterial proteins in said recipient to an indicator solution comprising a color indicator and a β-lactam compound selected from the group consisting of aminopenicillins, natural penicillins, carboxypenicillins and ureidopenicillins; and,
determining the presence or absence of a β-lactamase from the color of the indicator solution after incubation.
2. The method of claim 1 , which comprises:
(1) providing a filter system comprising a recipient comprising a filter at or in vicinity of the bottom of the recipient, wherein the filter is adapted to receive said sample and to retain bacteria and/or bacterial proteins contained in the sample, wherein said filter system is adapted to centrifugation;
(2) adding said sample in said recipient of said filter system;
(3) filtering said sample through said filter for separating bacteria from the sample;
(4) if not done previously, exposing bacteria to a surfactant solution;
(5) adding an indicator solution comprising at least one β-lactam compound and a colour indicator into the recipient comprising bacterial proteins;
(6) incubating the recipient comprising bacterial proteins and said indicator solution;
(7) determining the presence of a β-lactamase by detecting a color change of said indicator solution, and the absence of a β-lactamase by detecting an absence of a color change of said indicator solution.
3. The method of claim 1 , wherein said filter system is a centrifuge tube filter system comprising a filter cup comprising a filter and a centrifuge tube for harbouring said filter cup.
4. The method of claim 1 , wherein said color indicator is phenol red.
5. A method for identifying infections treatable with a penicillin compound, the method comprising:
providing a sample comprising or derived from a body fluid taken from a patient suffering from an infection;
loading the sample onto a recipient comprising a filter at or in vicinity of the bottom of the recipient, wherein the filter is adapted to receive said sample and to retain bacteria and/or bacterial proteins contained in the sample, wherein said recipient is adapted to centrifugation;
filtering said sample by centrifuging said recipient comprising said filter;
exposing bacteria to a surfactant solution and to a penicillin compound selected from the group consisting of amoxicillin, penicillin G, penicillin P, penicillin V, ampicillin, pivampicillin, hetacillin, bacampicillin, metampicillin, talampicillin, and epicillin;
exposing bacterial proteins in said recipient to an indicator solution comprising a color indicator and a β-lactam compound; and,
determining the presence or absence of a β-lactamase from the color of the indicator solution after incubation.
6. The method of claim 5 for identifying urinary tract infections treatable with a penicillin compound wherein said sample is urine sample.