Method and medium for use in detecting E. coli and total coliforms
AssigneeHach Company
InventorMichael A. Grant
Life of this patent
Estimating the term…
Abstract
A selective culture medium which permits simultaneous detection of total coliform and Escherichia coli in a test sample with a single growth phase incubation period. The culture medium includes the required components of: (i) carbon nutrients, (ii) a nitrogen nutrient, (iii) a source of metabolizable potassium, (iv) a source of metabolizable phosphate, (v) vitamins, (vi) minerals, (vii) amino acids, (viii) sodium pyruvate, (ix) a bactericidal system selective for non-coliform bacteria which includes methylene blue, erythromycin and an azide, and (x) a sensible indicator selectively metabolized by Escherichia coli to the exclusion of other coliforms.
Claims13
A culture medium which provides for selective growth of coliforms and simultaneous detection of coliforms and Escherichia coli as distinct from other coliforms, and which does so with the use of a chromogenic indicator, to the exclusion of use of any fluorogenic indicators, consisting essentially of:
- a media containing a carbon nutrient source, a nitrogen nutrient source, a source of metabolizable,potassium, a source of metabolizable phosphate, a source of vitamins, a source of minerals, a source of amino acids, and sodium pyruvate;
- a bacterial system selective for non-coliform bacteria which includes methylene blue, erythromycin, and an azide;
- a nonionic surfactant for enhancing visibility of bacterial colonies by increasing colony diameter;
- and
- a .beta.-glucuronidase substrate selectively metabolized by Escherichia coli to the exclusion of other coliforms.
A selective culture medium providing simultaneous detection of total coliform and Escherichia coli with a single growth phase incubation period comprising:
- (a) a carbon nutrient source;
- (b) a nitrogen nutrient source;
- (c) a source of metabolizable potassium;
- (d) a source of metabolizable phosphate;
- (e) a source of vitamins;
- (f) a source of minerals
- (g) a source of amino acids;
- (h) sodium pyruvate;
- (i) a bactericidal system selective for non-coliform bacteria which includes methylene blue, erythromycin and an azide;
- and
- (j) a .beta.-glucuronidase substrate selectively metabolized by Escherichia coli to the exclusion of other coliforms.
A selective culture medium providing simultaneous detection of total coliforms and Escherichia coli from a single growth phase incubation period comprising:
- (k) about 0.1 to 30 g/l lactose,
- (l) about 0.01 to 50 g/l mixed proteins,
- (m) about 0.001 to 20 g/l monobasic potassium phosphate,
- (n) about 0.002 to 40 g/l dibasic potassium phosphate,
- (o) about 0.01 to 20 g/l yeast extract,
- (p) about 0.01 to 10 g/l magnesium sulfate,
- (q) about 0.01 to 10 g/l sodium chloride,
- (r) about 0.005 to 40 g/l sodium pyruvate as a protective agent,
- (s) a bactericidal system selective for non-coliform bacteria of:
- 1) about 0.0001 to 0.1 g/l methylene blue,
- 2) about 0.0001 to 0.05 g/l erythromycin, and
- 3) about 0.005 to about 0.04 g/l azide, and
- 4) about 0.2 to 10 g/l nonionic surfactant,
- (t) about 0.001 to 1.0 g/l of an indicator selectively metabolized by Escherichia coli to the exclusion of other coliforms selected from the group consisting of the ammonium and sodium salts of 5-bromo-4-chloro-3-indolyl-.beta.-D-glucuronic acid cyclohexane;
- (u) 0.001 to 20 g/l methionine for enhancing the formation of glucuronidase by Escherichia coli growing in the medium;
- and
- (v) 0.001 to 0.5 g/l triphenyltetrazolium chloride as a highlighting dye metabolized by coliforms.
A culture medium which provides for selective growth of coliforms and simultaneous detection of coliforms and Escherichia coli as distinct from other coliforms, and which does so with the use of a chromogenic indicator, to the exclusion of use of any fluorogenic indicators, consisting essentially of:
- a media containing a carbon nutrient source, a nitrogen nutrient source, a source of metabolizable potassium, a source of metabolizable phosphate, a source of vitamins, a source of minerals, a source of amino acids, and sodium pyruvate;
- a bacterial system selective for non-coliform bacteria which includes methylene blue, erythromycin, and an azide;
- a .beta.-glucuronidase substrate selectively metabolized by Escherichia coli to the exclusion of other coliforms;
- and
- a recovery agent.
Dependencies are inferred from the claim text.