EC Medium was designed to improve the isolation and detection of E coli in contaminated water, milk and shellfish. USBio recommends that EC Medium be used for the determination of water pollution. The addition of 4-methylumbelliferyl-B-D-glucuronide (MUG) to EC Medium allows for the rapid detection (4-24 hours) of E coli when the incubated medium is observed for fluorescence using a long-wave UV light (365nm) source. It can also detect anaerogenic E. coli strains. Most strains of E. coli produce B-glucuronidase which hydrolyzes MUG to the fluorogenic compound 4-methyl-umbelliferone. Studies by Feng and Hartman noted that most E. coli strains (96%) and all enterotoxigenic E. coli strains (100%) and a moderate number of Salmonella (17%) and Shigella (40%) stains produce B-glucuronidase. False positives can also be caused by Streptococcus sp. To eliminate false positive results with oyster samples an enrichment step in Lauryl Sulfate Broth is recommended and then subsequent transfer to EC Medium with MUG.
Used in the isolation of E. coli from water, milk and shellfish by a fluorogenic method.
Components shown as g/liter:
Casein Digest of Peptone 20.0
Lactose 5.0
Sodium Chloride 5.0
Bile Salts Mixture 1.5
Monopotassium Phosphate 1.5
Disodium Phosphate 4.0
MUG 0.05g
Total: 37g/liter