Unit and method for preparing a sample for the microbiological analysis of a liquid
View Patent ↗A method comprising obtaining a preparation unit comprising a filter module and a collection for each liquid coming from the filter module, with the filter module comprising an inlet compartment as well as an evacuation compartment for the liquids, the filter and collection modules being rotatably mounted relative to each other; disposing the filter and collection modules in a first position; passing a liquid from the filter module to attain the collection module; disposing the filter and collection modules relative to each other in a second position, and passing another liquid from the filter module to attain the collection module.
1. A method of preparing a sample for the microbiological analysis of a predetermined volume of liquid that contains microorganisms, comprising:
the step of obtaining a preparation unit comprising a filter module having a membrane, and a collection module for each liquid coming from said filter module, with said filter module comprising an inlet compartment for inletting a predetermined volume by an inlet opening of said filter module, said inlet compartment being adapted to contain the whole of said predetermined volume, as well as an evacuation compartment for evacuating said predetermined volume by an evacuation opening of said filter module to said collection module, said evacuation compartment being separated from said inlet compartment by said membrane, the filter and collection modules being rotatably mounted relative to each other, and having, relative to each other, a first relative predetermined position, in which said evacuation opening of said filter module is in register with a first opening of said collection module and a second relative predetermined position different from said first position, in which said evacuation opening of said filter module is in register with a second opening of said collection module; wherein said inlet and evacuation compartments are on opposite sides from each other relative to said membrane with said inlet compartment being arranged such that, when said predetermined volume is in said inlet compartment, the liquid is in contact with the filter membrane over at least the majority of its surface;
the step of disposing the filter module and collection module of that unit relative to each other in said first predetermined position;
the step of passing said predetermined volume of liquid that may contain microorganisms from the filter module to attain the collection module through said evacuation opening of the filter module and through said first opening of the collection module;
the step of disposing the filter module and collection module relative to each other in said second predetermined position; and
the step of passing a predetermined volume of another liquid from the filter module to the collection module through said evacuation opening of the filter module and through said second opening of the collection module by centrifugation.
2. A method according to claim 1 , wherein it comprises, prior to said step of passing said predetermined volume of said another liquid through said evacuation opening of the filter module and through said second opening of the collection module, the step of selecting as another liquid, a liquid adapted to cause the lysis of the microorganisms retained on said filter membrane, the step of depositing on said filter membrane said predetermined volume of said another liquid, and then the step of leaving said another liquid to act on said microorganisms for a predetermined time.
3. A method according to claim 2 , wherein it comprises, subsequent to the step of passing said predetermined volume of said another liquid through said evacuation opening of the filter module and through said second opening of the collection module, the step of retrieving said predetermined volume of said another liquid for analysis.