CHROMOGENIC E.COLI O157 AGAR
A selective chromogenic medium for the detection of E.coli O157.
Code: CB1/605
Typical formula g/l
| Peptone mix | 17.0 |
| Bile salts No.3 | 1.5 |
| Agar | 12.0 |
| Chromogenic mixture | 0.5 |
pH 7.2 +/- 0.2
Directions
Suspend 31g in 1000 ml of cold distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Cool to 50°C and distribute into sterile petri dishes.
Description
Chromogenic E.Coli O157 Agar is a selective and differential medium for the isolation and immediate identification of E.coli O157. The selectivity of the medium is obtained by the presence of Bile Salts No.3, thus Gram-positive bacteria are completely inhibited. The Enterobacteriaceae differentiation is obtained by the presence of a chromogenic mixture, which allows the detection of E.coli O157, which develops on the medium with purple colonies. E.coli strains not belonging to O157 serotype, Citrobacter, Enterobacter, Klebsiella, Serratia grow with blue-green colonies. E. hermanni grow with colourless colonies.
Method
Use the medium with the normal laboratory procedures, incubating the inoculated plates at 37°C for 24 +/- 2 hours. Confirm the identification with the appropriate immunological tests.
User quality assurance (24 h-37°C)
Productivity control
E.coli O 157 ATCC 43888: growth, purple colonies
Specificity control
E.coli ATCC 25922: growth, blue colonies
Selectivity control
E.faecalis ATCC 19433: inhibited
Storage
Dehydrated medium: 2-8°C
User prepared plates: 24 hours at 2-8°C