CHROMOGENIC COLIFORM AGAR (CCA) (ISO 9308 : 2014)

Coliforms including Escherichia coli are used as primary indicators of faecal contamination in water and food industries. Their presence and enumeration in samples is used as an index of the presence of faecal matter and is indicative of the possible presence of enteric pathogens. Chromogenic Coliform Agar (CCA) is a fast, accurate, and efficient way to detect coliforms and E. coli during microbiological quality testing of water and food samples. Escherichia coli are also the most common pathogen in urinary tract infections. This product incorporates the company’s chromogenic galactoside that detects clinical levels of coliforms with high sensitivity. The composition and performance criteria of Chromogenic Coliform Agar (CCA) are as per the specifications laid down in ISO 9308-1:2014.

This medium contains enzymatic digest of casein, yeast extract, sorbitol and sodium pyruvate for growth of microorganisms, as sources of carbon, nitrogen, fermentable carbohydrate and other growth nutrients. Disodium hydrogen phosphate and sodium dihydrogen phosphate are the buffering agents.The osmotic balance of the medium is maintained by sodium chloride. L-Tryptophan improves the indole reaction and gives improved differentiation between Escherichia coli and other coliforms. Tergitol-7 inhibits gram-positive bacteria. The two chromogens used; salmon-β-D-galactoside and X-glucuronide helps in differentiation of Escherichia coli and other coliforms on the basis of colony colour. The enzyme β-D-galactosidase cleaves salmon-β-D-galactoside, and gives a salmon red colour to the coliform bacteria. E. coli have β-D galactosidase and β-D-glucuronidase enzymes to cleave both the chromogens, which give blue-violet colour to colonies. Expression of β-D-galactosidase is strengthened in the presence of IPTG. Chromogenic Coliform Agar is a gelling agent.

for determination of coliforms and Escherichia coli in water samples