Minnesota Mining and Manufacturing Company

Marlys E Lund

Patrick A Mach

Robert L Nelson

John K Hood

An article for detecting thermostable nuclease positive, potentially enterotoxigenic, staphylococci, containing unhydrolyzed nucleotides, toluidine blue O, and a binder, wherein the article is adapted for placement against a sample suspected of containing enterotoxigenic staphylococci. A method of detecting thermostable nuclease positive staphylococci in a sample utilizing the article, and a kit for the detection of thermostable nuclease positive staphylococci containing the article, are also described.

Article and method for detection of enterotoxigenic staphylococci

A medium for detecting staphylococci is described. The medium contains components selective for growing staphylococci, and a glucopyranoside indicator substance in sufficient quantity to distinguish colonies containing Bacillus and other microorganisms from colonies containing staphylococci. Methods of detecting staphylococci utilizing such medium are also described.

Culture medium and methods for detecting staphylococci

The present invention exploits the herein first reported, empirical observation that even though staphylococci produce the enzyme, beta-glucosidase, this genus of bacteria is not able to produce a metabolite that will enzymatically react with 5-bromo-4-chloro-3-indolyl-beta-D-glucopyranoside, a substrate commonly used to detect the presence of beta-glucosidase produced by other bacteria. In view of this unexpected observation, one embodiment of the present invention includes a selective medium containing inhibitors to enhance staphylococci growth as well as a first glucopyranoside substrate, such as 5-bromo-4-chloro-3-indolyl-beta-D-glucopyranoside, and a second phosphatase substrate, Such as 6-chloro-3-indolylphosphate or 5-bromo-6-chloro-3-indolylphosphate. In a particularly preferred embodiment of this invention, a thin film culture plate device, such as a PETRIFILM culture plate device, is prepared using a dry culture medium containing selected inhibitors, a first glucopyranoside substrate and a second phosphate substrate. When the thin film culture plate device is inoculated with a sample and then incubated for a sufficient period of time, staphylococci in the sample will produce colonies on the thin film device having a red color and other bacteria in the sample will produce colonies on the device having a blue color.

Method for detecting staphylococci

The present invention exploits the herein first reported, empirical observation that even though staphylococci produce the enzyme, beta-glucosidase, this genus of bacteria is not able to produce a metabolite that will enzymatically react with 5-bromo-4-chloro-3-indolyl-beta-D-glucopyranoside, a substrate commonly used to detect the presence of beta-glucosidase produced by other bacteria. In view of this unexpected observation, one embodiment of the present invention includes a selective medium containing inhibitors to enhance staphylococci growth as well as a first glucopyranoside substrate, such as 5-bromo-4-chloro-3-indolyl-beta-D-glucopyranoside, and a second phosphatase substrate, such as 6-chloro-3-indolylphosphate or 5-bromo-6-chloro-3-indolylphosphate. In this embodiment, staphylococci in a sample will produce metabolites that will react with the phosphate substrate in the medium to produce colonies having red to red-violet color while other bacteria in the sample will produce beta-glucosidase that will react with the glucopyranosidase substrate in the medium and produce colonies having a blue color. In a particularly preferred embodiment of this invention, a thin film culture plate device, such as a PETRIFILM culture plate device, is prepared using a dry culture medium containing selected inhibitors, a first glucopyranoside substrate and a second phosphate substrate. When the thin film culture plate device is inoculated with a sample and then incubated for a sufficient period of time, staphylococci in the sample will produce colonies on the thin film device having a red color and other bacteria in the sample will produce colonies on the device having a blue color.

A wand assembly having an elongate rod with a lower end having a groove or grooves formed therein. When contacted with (e.g., touched to) a colony, the lower end is able to ingest a predetermined quantity of bacteria into the groove or grooves by capillary action. The wand assembly is particularly suitable for ingesting very small quantities of bacteria, e.g., on the order of 1.times.10.sup.7 colony forming units, since it is provided with a collar that is releasably attached to the rod, and can be detached from the rod after the lower end has been touched to a colony, in a manner that wipes excess, unwanted bacteria from the peripheral surface of the rod.

Device for obtaining predetermined amounts of bacteria

A microbial profile tray formed of a light transmitting material and having a planar surface in which a plurality of uniformly shaped cup-like receptacles have their openings. Some of these cup-like receptacles have a surface which causes transmitted light to be diffused. The cup-like receptacles having the light diffusing surface can be used as control cups to simulate the turbidity which occurs in cups not having this light diffusing surface but in which microbial growth has occurred.

Disposable microbial profile tray

A broth medium for the detection of DNAse-positive microorganisms. The medium contains conventional nutrients for growing the microorganisms, a source of essential divalent cations to insure activity of the DNAse and a biological indicator comprising DNA, toluidine blue and lambda carrageenan in sufficient quantity so that the medium turns from blue to a visually distinguishable reddish-pink or reddish-violet color in the presence of DNAse-positive microorganisms.

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Eden Prairie, MN, United States of America

Marlys E Lund