Rainbow™ - Biolog | Shigella / Aeromonas Detection

For laboratory use as a selective, chromogenic culture medium to aid in the detection and isolation of Shigella and Aeromonas species. Not for human in vitro diagnostic use.

Summary of Test

Rainbow Agar Shigella / Aeromonas was developed to provide laboratories with a better culture medium for directly isolating pathogenic strains of Shigella and Aeromonas. Species of these genera can be important causative agents of gastroenteritis. The medium is inhibitory to gram-positive bacteria and most non-enteric gram-negative bacteria, but is not toxic to the target species. Escherichia coli is significantly inhibited, and colonies that grow are blue. Most other enteric species growing on the medium will also form blue colonies. Strains of all four Shigella species (sonnei, flexneri, boydii and dysenteriae) as well as some Aeromonas species (hydrophila, jandaei and tructi) grow as large or medium-sized orangered colonies. Shigella can be preliminarily differentiated from Aeromonas with an oxidase test (Shigella is oxidase-negative, Aeromonas is oxidase-positive).

Contents

This sealed packet contains dry powder to make Rainbow Agar Shigella / Aeromonas. 71.5 grams of powder will make 1 liter or approximately 50 plates.

Preparation

This medium can be prepared in any volume to suit the user’s needs. To prepare 1 liter of Rainbow Agar Shigella / Aeromonas, mix 71.5 grams of powder into 1 liter of purified water in a container large enough to hold twice the volume to be prepared. Bring it to a boil in a microwave oven or on a hot plate. Watch the medium as it is heated and as soon as it reaches a full boil, remove it immediately from the heat. The medium is very sensitive to heat and CANNOT BE AUTOCLAVED. Cool agar to 45-50°C before pouring. Dispense approximately 20 ml of media into each petri plate. The medium is ready to use as soon as it has cooled, gelled and the surface has dried. The final medium should be clear and light green in color.

No pH adjustment is needed. The final pH should be pH 7.2-7.6. For samples that have a high background count of enteric bacteria, 100 mg/L sodium selenite can be added to make the medium more selective.

Storage

Rainbow Agar Shigella / Aeromonas powdered medium is extremely hygroscopic and should be stored at 2°C to 25°C in a dry environment. Unopened packets may be stored in this manner until the expiration date on the label.

User Quality Control

The following organisms are recommended if quality control is desired or required. Inoculate Rainbow Agar Shigella / Aeromonas plates with the following strains by streaking for isolation, then incubate for 24 hours at 35°C without elevated CO2. Colony color should be read from isolated colonies.

	ATCC®	Color on Rainbow Agar
Organism	number	Shigella / Aeromonas

Shigella sonnei	25931	Orange-red
Shigella flexneri	12022	Orange-red
Aeromonas hydrophila	35654	Orange-red
Escherichia coli	25922	Blue

Procedure

Inoculate the medium by streaking or spreading a sample suspected of containing Shigella or Aeromonas on the surface of the medium. Incubate the platesfor 20 to 24 hours, or longer, at 35°C without elevated CO₂ and observe for the presence of colored colonies.

Expected Results

Organism

Growth

Colony coloration

Shigella sonnei	Good	Orange-red
Shigella flexneri	Good	Orange-red
Shigella boydii	Good	Orange-red
Shigella dysenteriae	Good	Orange-red
Aeromonas hydrophila	Good	Orange-red
Escherichia coli	Partially Inhibited	Blue

Limitations

This medium should not be used as the sole basis for identification of microorganisms. Any colony suspected of being Shigella or Aeromonas should be tested further to verify its identity using an approved confirmatory protocol.

Biolog Ordering Information

Rainbow Agar Shigella / Aeromonas

Catalog Number

Description

80302

Powder- 71.5 grams

Shigella sonnei

Escherichia coli

| Rainbow™ Agar 0157 | Rainbow™ Agar Salmonella | Rainbow™ Agar Shingella / Aeromonas |

BiolinkArg / Bioscan - Representante exclusivo de Biolog en Argentina