Description

INTENDED USE

CBSAlife EC Medium is a culture medium for the detection of coliform bacteria at 35°C and of Escherichia coli at an elevated temperature (44.5 or 45.5°C).

SUMMARY AND EXPLANATION

CBSAlife EC Medium was devised by Hajna and Perry and is used for the examination of water, milk, shellfish and other material for evidence of fecal pollution. Tennant et al. reported on the use of this medium for the estimation of E. coli densities in seawater and shellfish. Fishbein and Surkiewicz used the EC confirmation test for recovery of E. coli from frozen foods and nut meats and reported that the test worked optimally when conducted at 45.5°C with incubation being limited to 24 hours.

EC Medium is recommended for use in the fecal coliform Most Probable Number (MPN) procedure for the examination of water, wastewater and foods. The procedure employing EC Medium provides information regarding the source of the coliform group (fecal or nonfecal) when used as a confirmatory test. It should not be used for the direct isolation of coliforms since prior enrichment in a presumptive medium for optimal recovery of fecal coliforms is required.

PRINCIPLE

EC Medium contains peptone as a source of nutrients. Lactose provides fermentable carbohydrate for the growth of coliforms. Bile salts are inhibitory for gram-positive bacteria, particularly bacilli and fecal streptococci. The medium has a strong potassium phosphate buffering system to control the pH in the presence of considerable fermentative action. Sodium chloride maintains the osmotic balance of the medium.