- Macconkey Agar with Sorbitol is Selective and differential medium for the research of E. coli 0157:H7 which cause Hemorrhagic Collitis and HUS (haemolytic uraemic syndrome).
Colonoscopic view of colon – haemorragic colitis by E. coli 0157:H7
Macconkey Agar with Sorbitol Composition
Macconkey Agar with Sorbitol Composition
Preparation:
- Suspend 51,5 grams of the medium in one liter of distilled water. Heat to boiling with frequent agitation until totally dissolved. Dispense and sterilize at 121° C (15 lbs psi) for 15 minutes. Distribute into sterile Petri dishes. If needed, allow the plate surface to dry.
Uses:
- Sorbitol MacConkey Agar is based on the formula developed by Rappaport & Henig. This medium is recommended for the research of E. coli 0157:H7. The composition is similar to MacConkey Agar but the lactose has been substituted by sorbitol. E. coli 0157:H17 does not ferment the sorbitol and therefore produces colourless colonies. Most of the other E. coli do ferment it and therefore their colonies are pink.
- E. coli 0157:H7 has been recognized as being responsible for haemorragic colitis, characterized by a blooding diarrhea with intense abdominal ache. Optimal temperature for E. coli 0157:H7 is 35°C -37°C.
E coli O157:H7 on a sorbitol-MacConkey agar plate
Arrow indicates distinctive colourless E coli O157:H7 colony.
