Changes

Coliscan media incorporate a patented combination of color-producing chemicals and nutrients that mark coliforms and E. coli in differing colors for easy identification and isolation. This means that a test sample of water or other material may be added to the medium, and coliform bacteria will grow as pink-magenta colonies while E. coli will grow as purple-blue colonies. Other bacterial types will generally grow as non-colored colonies. There are two approaches to the Coliscan method: Coliscan Easygel and Coliscan-MF.

Easygel is produced by Micrology Labaroties, this company specializes in easy-to-use, accurate water testing and microbiology applications.

Their patented testing methods eliminate the dependence on agar and expensive equipment, and offer the easiest and most effective ways to test water for coliform and E. coli bacteria.

==Suitable Conditions==

Both the Easygel and the MF approaches work very well when used properly. The Easygel® is provided as a liquid medium which contains a gelling agent that causes the medium to solidify when it is poured into a petri dish containing a layer of calcium ions so that it resembles a standard prepoured agar plate. The gelled dish can be streaked or swabbed with test material or a small test sample (generally 1-5 mL) can be added prior to pouring. The MF consists of a liquid medium without a gelling agent which is used to saturate a sterile pad in a small petri dish in conjunction with a micropore membrane filter which has filtered an aqueous test sample, with the sample generally being of a larger volume. Both approaches use very similar formulations and ingredients with the exception of the gelling agent. (For those familiar with the membrane filter approach where the medium is agar based and a solid layer is formed in a dish as the foundation for the membrane filter, Coliscan® can also be prepared in this manner. It is not currently offered in this format other than by custom request.)

The Easygel® is designed for use when the number of target organisms/mL of sample is quite high and therefore the number of colony forming units/plate will be high enough to count with accuracy when a 1-5 mL sample is added directly to the medium.

The MF is designed for situations where the test sample has very low numbers of target organisms and it is necessary to validate the absence or very low count of the target organisms, while the Easygel approach is excellent for determining populations of target organisms when they are commonly present in relatively large numbers in the test materials.

Either collect your water sample in a sterile container and transport the water back to the test site, or take a measured water sample directly from the source and place directly into the bottle of Coliscan Easygel. Water samples kept longer than one (1) hour prior to plating, or any Coliscan Easygel bottle that has had a sample placed into it for transport longer than ten (10) minutes, should be kept on ice or in a refrigerator until plated. <br>

# Label the petri dishes with the appropriate sample information. A permanent marker or wax pencil will work. <br>

## Place 5 ml (about 1 teaspoon) of straight bleach onto the surface of the medium of each plate. Allow to sit at least 5 minutes. Place in a watertight bag and discard in trash. <br>

This test method utilizes well established, widely accepted criteria for the recognition of coliforms and E. coli and proper application of the method will result in accurate results. Therefore, if you suspect that your water is dangerously contaminated based on the results you get using Coliscan Easygel, you should contact your local health department and ask for their help in performing an official assessment of water. <br>

Non-fecal coliforms are widely distributed in nature, being found both as naturally occurring soil organisms, and in the intestines of warm-blooded animals and humans. Fecal coliforms are coliforms found naturally only in the intestines of warm-blooded animals and humans. Fecal coliform contamination is therefore the result of some form of fecal contamination. Sources may be either animal or human.

Depending on the contents of the kit, and which type of gel is used, the cost of an Easygel kit ranges between $14 and $55.