Chromogenic medium provides a rapid and easily visualised result within 24 hours, reducing the need for further lengthy confirmation steps
Oxoid has launched a new chromogenic culture medium to enhance the detection and enumeration of E coli and coliforms - important indicators of environmental and food hygiene.
Oxoid Selective E coli/coliform chromogenic medium provides a rapid and easily visualised result within 24 hours, reducing the need for further lengthy confirmation steps.
Oxoid Selective E coli/coliform chromogenic medium can be used without the need for pre-enrichment or the use of a filter membrane.
The selective agent in the medium, sodium lauryl sulphate, inhibits the growth of gram-positive microorganisms that may interfere with the growth of the target organisms.
Two chromogens then allow E coli and coliform colonies to stand out from any other organisms that may grow on the selective medium, allowing accurate colony counts to be obtained of each.
Chromogen X-Gal detects the presence of b-galactosidase activity in coliforms (including E coli), causing them to be bright pink in colour.
In addition X-Glu detects the enzyme b-glucuronidase, which is possessed by E coli but not by other coliforms.
The resulting blue chromophore causes E coli colonies to appear purple, allowing them to be easily differentiated from other coliforms.
