Method for detecting and enumerating of low concentrations of listeria
AssigneeSensilist AS
InventorsTaran SKJERDAL, Tone MATHISEN FAGERENG, Agnete FÆGRI, Isaac KOFITSYO SEWORNU CUDJOE
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Abstract
The present document is directed to a method for the detection and/or enumeration of Listeria bacteria, such as Listeria monocytogenes in a sample, said method comprising culturing a sample possibly containing Listeria bacteria in a culture medium comprising rhamnose, one or more of an antibiotic, a pH colour indicator and LiCl.
Claims15
A method for the detection of rhamnose fermenting Listeria spp., such as Listeria monocytogenes, in a sample, said method comprising or consisting of the steps of:
- i) preparing a suspension of a sample potentially containing Listeria bacteria in a first culture medium, said first culture medium comprising rhamnose, one or more of an antibiotic, a pH colour indicator and LiCl;
- ii) incubating said suspension at conditions allowing the growth of Listeria bacteria;
- and
- iii) identifying positive samples.
The method according to any one of the preceding claims, wherein said sample possibly containing rhamnose fermenting Listeria spp. is obtained by dividing said sample into small pieces such as by homogenization, slicing and/or chopping either before step i) is performed and/or in the first culture medium of step i).
The method according to any one of the preceding claims wherein said antibiotic is one or more of nalidixic acid, ceftazidime, polymyxin B sulfate, cycloheximide, amphotericin B, preferably a combination of two or more of any of said antibiotics.
A method according to any one of the preceding claims wherein said pH colour indicator is phenol red.
A method according to any one of the preceding claims wherein said LiCl is present in an amount of about 5-17 g/l, such as about 7-13 g/l, such as about 10 g/l.
A method according to any one of the preceding claims wherein said rhamnose is present in an amount of about 5-17 g/l, such as about 7-13 g/l, such as about 10 g/l.
The method according to any one of the preceding claims, wherein said sample is a food sample, an environmental sample, or a sample from an animal, such as a human, such as a tissue sample or a feces sample.
The method according to any one of the preceding claims, wherein said food sample is raw or processed meat, poultry or fish products, vegetables or a ready-to-eat food product.
The method according to any one of the preceding claims, wherein said method is performed in a closed system.
A culture medium for the growth and/or detection of rhamnose fermenting Listeria spp., such as Listeria monocytogenes, said culture medium comprising:
- e) rhamnose in a concentration of about 5-15 g/l, such as about 7-13 g/l, such as about 10 g/l;
- f) one or more antibiotics, such as nalidixic acid, ceftazidime, polymyxin B sulfate, cycloheximide, amphotericin B, preferably at least two of these;
- g) a pH colour indicator, such as phenol red;
- and
- h) LiCl in a concentration of about from 5 to about 15 g/l, such as about from 7 to about 13 g/l, such as about 10 g/l.
A kit for detecting and/or enumerating rhamnose fermenting Listeria spp., such as Listeria monocytogenes, in a sample, said kit comprising:
- a) a container comprising a culture medium comprising or consisting of rhamnose, one or more of an antibiotic, a pH colour indicator and LiCl;
- b) a container or multi-well tray for cultivating a sample possibly containing Listeria bacteria;
- and
- c) optionally a colour chart for identifying positive samples;
- and
- d) optionally instructions for use.
Dependencies are inferred from the claim text.