Harlequin® E. coli/Coliform Agar

E. coli / Coliform Agar is for the simultaneous enumeration of Escherichia coli and coliforms in food and environmental samples and is not intended for use in the diagnosis of disease or other conditions in humans.

This dual chromogenic substrate medium makes the different colony types easy to distinguish allowing rapid counting of both E. coli and coliforms on a single agar.

Based upon the formulation of Tryptone Bile Agar, the medium has been modified by the addition of two chromogenic substrates, one to detect the ß-glucuronidase enzyme (X- glucuronide) and another to detect the ß-galactosidase enzyme (magenta-ß-gal). Typical E. coli strains possess both enzymes but only cleave the X-glucuronide substrate, thereby producing blue-green colonies. Typical coliforms, however, possess only the ß-galactosidase enzyme and produce rose-pink colonies.

The colony types are easily distinguishable, even in the presence of other organisms, or when large numbers are observed, making simultaneous enumeration of E. coli and coliforms a quick and simple procedure.