Mac Conkey-Sorbitol ChromoSelect Agar

The culture medium complies with the requirements of the DIN Norm 10167 for the detection of Escherichia coli (E. coli) serotype 0157:H7 in foods as well as with the methods of FDABAM for the isolation of enterohemorrhagic E. coli (EHEC).

Principle
Microbiological method.

Mode of Action
Bile salts mixture and crystal violet largely inhibit the growth of the Gram-positive microbial flora. The addition of Cefixime Potassium tellurite (CT) Supplement increases the selectivity for E. coli 0157:H7 and suppresses the remaining accompanying flora. For the detection of E. coli 0157:H7 the CT-SMAC Agar method is superior to the HC Agar (SZABO) method according to the study of WEAGANT (1995).Sorbitol, together with the pH indicator neutral red, is used to detect sorbitol-positive colonies and turning them red in colour.
Sorbitol-negative strains, on the other hand, form colourless colonies.

Typical Composition (g/litre)
Peptone 20.0; sodium chloride 5.0; bile salts No. 3 1.5; sorbitol 10.0; crystal violet 0.001; neutral red 0.03; agar-agar 15.0.

Preparation and Storage
Usable up to the expiry date when stored dry and tightly closed at +15 to +25°C. Protect from light.
After first opening of the bottle the content can be used up to the expiry date when stored dry and tightly closed at +15 to +25°C.
Suspend 51.5 g in 1 litre of demin. water, autoclave (15 min at 121 °C), pour plates. pH: 7.1 ± 0.2 at 25 °C.
The plates are clear and red and are stable for up to 6 months when stored at +2-8 °C.
CT-SMAC Agar
Suspend 25.8 g in 500 ml of demin. water, autoclave (15 min at 121°C).
Dissolve the lyophilisate of one CT Supplement in the original vial by adding about 1ml of sterile distilled water.
Mix gently and add the contents to the sterile, still liquid SMAC Agar cooled below 50 °C. Pour plates.
pH: 7.1 ± 0.2 at 25 °C.
The plates are clear and red and are stable for up to 6 months when stored at +2-8 °C.