Bacterial screening system with enhanced shelf life
AssigneeCambridge Bioscience Corporation
InventorsJohn W. Roberts, Karen E. DeBell
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Abstract
A tetrazolium-based system for testing for the presence of organisms or cells in a specimen includes in one embodiment a mixture of a substrate and an indicator system, wherein the overall system is buffered to a pH above 8.0, and in a preferred embodiment at about a pH of 9.0 when mixed. The substrate solution and indicator solution are not mixed until shortly before use. The indicator solution is buffered at a pH of approximately 3.3, thereby enhancing the shelf life. The substrate may consist of glucose with at least one amino acid in a buffered solution formulated such that, by mixing equal parts with the indicator solution, a pH above 8, preferably 9.0 results.
Claims3
A disposable test system for testing for the presence of bacterial organisms in a specimen, the system consisting essentially of:
- a buffered substrate solution, for bacterial dehydrogenases in the specimen;
- and
- an indicator solution for detecting the presence of the bacterial dehydrogenases in the specimen, including
- (a) a tetrazolium salt;
- and
- (b) phenazine ethosulfate,
- wherein
- (i) the indicator solution is buffered to a pH of approximately 3.3, thereby enhancing the shelf life of the indicator solution,
- (ii) the substrate solution and the indicator solution are not mixed until shortly before use, wherein the shelf-life of the test system is enhanced, and
- (iii) the substrate solution is buffered to a sufficiently high pH so that the test system when mixed has a pH between 8.8 and 9.2, whereby enhanced test sensitivity is achieved without a resulting loss of test specificity.
Dependencies are inferred from the claim text.