Chromogenic Coliform Agar (CCA) is for the enumeration of Escherichia coli and Coliforms in water and is not intended for use in the diagnosis of disease or other conditions in humans. Chromogenic Coliform Agar (CCA) is recommended by ISO 9308-1 for the simultaneous detection and enumeration of β-glucuronidase-positive Escherichia coli and β-D-galactosidase positive coliform bacteria from water samples using membrane filtration. Peptone and yeast extract provide a source of nitrogen and essential vitamins. Sodium chloride maintains the osmotic balance and the phosphates buffer the media. Sodium Pyruvate, Sorbitol and Tryptophan aid in the recovery and detection of the target organisms. Tergitol™ 7 is a surfactant that acts as a selective agent. The dual chromogens are incorporated to differentiate between E. coli and coliforms based on their enzymatic activity. IPTG induces β-D-galactosidase and agar is the gelling agent. E. coli possess both β-D-galactosidase and β-glucuronidase activity so appear dark blue to violet. Coliform bacteria that are not E. coli possess only β-D-galactosidase so appear pink to red. Any organism able to grow that does not belong to these groups appears colorless. This medium conforms to the performance requirements of ISO 9308-1 2017.
