E.coli O157 Chromogenic Medium

Item code: CRM0007
 
Usages:
For rapid separation and identification of E. coli O157: H7.
                                                                    
Principle:
Peptone provide carbon and nitrogen; bile salts inhibit the growth of Gram-positive bacteria; and sodium chloride maintains osmotic equilibrium; agar as medium coagulant ; mixing carbohydrates into fermentable sugars; neutral red a pH indicator, the bacteria ferment the sugar acid colonies were pink; potassium tellurite inhibit non E. coli O157: H7 bacteria growth; pigment mixed with E. coli O157: H7 has enzymes that react specifically, hydrolysis of the substrate matter, releasing the color groups to produce blue-green light red colonies on the plate.
 
Formulation (per liter):
Peptone :8.6g
Sodium chloride:5g
Carbohydrate mix:25g
Neutral red :0.015g
Bile: 1.5g
Pigment mixed:0.3g
Agar: 15g
Final pH 7.0 ± 0.2
 
How to use:
1.Suspend 55.4g of the product , adding 1L of distilled or deionized water , heated to boiling stirring until completely dissolved, dispensing into flask.
2.After cooling the basal medium to 50 ? , adding 1 bottle of (SR0200) sterile potassium tellurite solution into the medium for per 100 ml . if the sample contains more variants bacteria, add 0.0025mg of cefixime into 100 ml of culture medium, mix and pour sterile Petri dish, after solidification spare.
3.According to the national standard, SN standards, FDA standards or other sample preparation methods, take an inoculation loop ring enrichment broth, streaked on the color plate, placed in 36 ± 1 ? cultured for 18-24 hours.
4.Observe the results. Picked up a blue-green color on the plate, flat and transparent, smooth edges, about 2mm in diameter suspicious colonies for further testing.
5.MicrogenTMGN-ID or API20E or biochemical test tube and serological tests can be used for further comformation of suspected E. coli O157: H7 colonies.
 
Quality control:
          This product appears light red after the pour plate, these strains were inoculated after 36 ± 1 ? cultured for 18-24 hours growth in the following table:
 
 
Bacteria name             bacteria NO.          growth situation         feature
E. coli O157: H7          NCTC12900              good             blue-green
E. coli                   HK70115                good             deep blue
E. coli                  ATCC25922               suppressed          Pink
Enterococcus faecalis      ATCC29212             suppressed             --
 
Storage: Keep container tightly closed, store in a cool, dry place, away from bright light.