E. coli O157:H7 Chromogenic Plating Medium

E. coli O157:H7 appears as blue-black domed colonies 1.5-2.5 mm in diameter with a black precipitate after 24 h at 35°C. Other enterics will either not grow or produce green, yellow, turquoise, white or colorless colonies. The Gram (+)s are inhibited.

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Mechanism

Our medium uses the X-β-D-galactopyranoside to detect the β-galactosidase produced by all E. coli and coliforms in the enteric family. With the addition of four sugars which E. coli O157:H7 strains are negative, coupled with a pH indicator this bacterium produces blue-black colonies. Other coliforms that ferment one or more of these sugars will produce green colonies which differentiate E. coli O157:H7 from other coliforms.

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Industry Types

Beef, poultry (packers and processors) and fresh produce and environmental sources including drinking water and soils.

See Product Brochure, Use Protocol, SDS, Certificate of Analysis and Medium Preparation for more information about our medium.

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Advantages/Benefits

1. Highly selective/differential using 5 different parameters for isolating E. coli O157:H7 from other bacteria.

2. Use of a stable β-galactosidase to reduce the chances of false negatives, thereby reducing additional time consuming and labor intensive identifications.

3. Water insoluble chromogenic lattice prevents the colony color from diffusing into the agar making detection and enumeration much easier.

4. The shelf life of prepared plates remains stable for at least 60 days, stored in the dark at 2-8°C. One bottle of plating medium powder and one box of supplements will make approximately 350 plates.

5. Listed in FDA’s BAM and can be used as one of the equivalent media in USDA/FSIS Microbiology Laboratory Guidebook. Also is the medium of choice in Japan.

Publications

*Onoue, Y., H. Konuma, H. Nakagawa, Y. Hara-kudo, T. Fujita, and S. Kumagai. 1999. Collaborative evaluation of detection methods for Escherichia coli O157:H7 from radish sprouts and ground beef. International Journal of Food Microbiology. 46: 27-36.

*Restaino, L., E.W Frampton, K.N. Turner, and D.R.K. Allison. 1999. A chromogenic plating medium for isolating Escherichia coli O157:H7 from beef. Letters in Applied Microbiology. 29: 26-30.

*BCM O157:H7 is R & F® E. coli O157:H7

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Ordering Information

M-0350R & F® Escherichia coli O157:H7 Chromogenic Detection System (500 g Bottle of Powder & one Supplement Box – Makes 340-360 Plates)

M-0300

R & F® Escherichia coli O157:H7 Chromogenic Plating Medium (500 g Bottle)

M-0310

R & F® Escherichia coli O157:H7 Supplement for Plating Medium (1 Box)

M-0360

R & F® Escherichia coli O157:H7 Chromogenic Prepared Plate (Minimum Order of 20 Plates – Shelf life is 60 Days)