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山東拓普生物工程有限公司

Shandong Tuopu Biol-Engineering Co.,Ltd

Cefiximine Rhamnose Sorbitol MacConkey Agar
(CR-SMAC Agar Base)

培養(yǎng)基配方
Composition per liter:
Peptone........................................................20.0g
Agar ..........................................................15.0g
Sorbitol.......................................................10.0g
NaCl............................................................5.0g
Rhamnose........................................................5.0g
Bile Salts No.3.................................................1.5g
Neutral Red....................................................0.03g
Crystal Violet................................................0.001g
Selective supplement solution ................................10.0mL
pH 7.1 ± 0.2 at 25°C
Source:  This medium is available as a premixed powder from Oxoid
Unipath.
Selective Supplement Solution:
Composition per 10.0mL:
Cefiximine ...................................................0.05mg
Preparation of Selective Supplement Solution:  Add cefiximine to
distilled/deionized water and bring volume to 10.0mL. Mix thorough-
ly. Filter sterilize.
Preparation of Medium: Add components, except selective sup-
plement solution, to distilled/deionized water and bring volume to
990.0mL. Mix thoroughly. Gently heat while stirring and bring to boil-
ing. Autoclave for 15 min at 15 psi pressure–121°C. Cool to 50°C.
Aseptially add selective supplement solution. Mix thoroughly. Pour
into sterile Petri dishes.
Use:  For the detection of Escherichia coli O157:H7. This is a elective,
differential medium based on Sorbitol MacConkey Agar with added
rhamnose and cefixime. This medium provides a selective base with
improved differentiation of E. coli O157. The addition of rhamnose
aids in the differentiation of Escherichia coli O157 from background
flora. Cefixime reduces the level of competing flora, particularly Pro-
teus spp., that often account for large numbers of non-sorbitol ferment-
ing colonies. E. coli O157 do not usually ferment sorbitol or rhamnose,
so will appear as straw colored colonies. However, rhamnose is fer-
mented by most sorbitol negative E. coli of other serogroups. These
colonies will be pink/red and will not be counted as presumptive E. coli
O157 colonies.