Patent

1. A method of distinguishing a colony of non- Salmonella microorganisms from a colony of Salmonella microorganisms, the method comprising

forming an inoculated culture device by combining in a dry film culture device comprising a film substrate and a cover sheet:

a dry selective growth medium that includes a gelling agent; nutrients to facilitate the growth of Salmonella microorganisms; and a plurality of selective agents that includes Nalidixic Acid, Streptomycin, and bile salts;

a first differential indicator system comprising 2-deoxy-D-ribose and a pH indicator;

a second differential indicator system comprising a chromogenic β-galactosidase enzyme substrate;

a third differential indicator system comprising urea; and

a predefined volume of a liquid sample;

wherein the dry selective growth medium is adhered to the substrate;

incubating the inoculated culture device for a period of time;

observing the inoculated culture device to detect a bacterial colony surrounded by an acid zone; and

observing the bacterial colony to detect a blue-green-colored zone proximate the colony, wherein the blue-green-colored zone is associated with a reaction involving the β-galactosidase enzyme substrates;

determining whether the bacterial colony is a Salmonella microorganism or a non- Salmonella microorganism;

wherein observing a bacterial colony that is surrounded by the acid zone and that does not have a blue-green-colored zone proximate the colony indicates the bacterial colony is a colony of Salmonella microorganisms;

wherein observing a bacterial colony that is surrounded by the acid zone and that does have a blue-green-colored zone proximate the colony indicates the bacterial colony is a colony of a non- Salmonella microorganisms.

2. The method of claim 1 , wherein forming the inoculated culture device comprises:

depositing the predefined volume of the liquid sample into a culture device that comprises the selective growth medium, the first differential indicator system, and the second differential indicator system;

incubating the inoculated culture device for a first period of time;

observing the inoculated culture device to detect a bacterial colony surrounded by an acid zone;

when a bacterial colony surrounded by the acid zone is observed, contacting the selective growth medium with a detection article comprising the third differential indicator system;

incubating the inoculated culture device for a second period of time; and

observing the inoculated culture device to detect a bacterial colony reacting with the urea.

3. The method of claim 2 , wherein incubating the inoculated culture device for a first period of time comprises incubating the inoculated culture device for about 0.5 hours to about 24 hours.

4. The method of claim 3 , wherein incubating the inoculated culture device for a first period of time comprises incubating the inoculated culture device for about 0.5 hours to about 6 hours.

5. The method of claim 2 , wherein incubating the inoculated culture device for a second period of time comprises incubating the inoculated culture device for about 30 minutes to about 360 minutes.