|Soya peptone||5 g|
|Sodium chloride||5 g|
|Ferric ammonium citrate||1 g|
|Sodium desoxycholate||1 g|
|Sodium thiosulphate||1 g|
|Agar||9 to 18 g|
|Water, distilled||1000 mL|
Final pH is 7.3 ± 0.2 at 25°C. Agar amount can be adjusted depending on the gel strength.
Grind the 5-bromo-4-chloro-3-indolyl-α-D-glucopyranoside with sodium chloride in a pestle and mortar to yield evenly distributed fine powder. Dissolve the other components in the water by boiling, remove from the heat and add the sodium chloride:5-bromo-4-chloro-3-indolyl-α-D-glucopyranoside mixture. Adjust the pH, if necessary, so that it is 7.3 ± 0.2 at 25°C after sterilization. Autoclave at 121°C for 15 minutes. Cool the medium to between 47°C and 50°C. Mix well and pour about 15 mL to 20 mL into sterile Petri dishes and allow to solidify on a cool even surface.
After the plates have been poured and dried upside down in the dark at room temperature for up to 48 h, they can be placed in petri plate sleeves (cutting a 0.5" to 1" hole in the sleeves to allow condensation to escape) and stored upside down at 2-8 ºC in the dark for up to 2 weeks.
Enterobacter sakazakii agar (DFI formulation) is available commercially from Oxoid, Lenexa, KS (Brilliance™ Enterobacter sakazakii Agar, Cat. No. CM1055). Follow the manufacturer’s instructions if using commercial dehydrated medium. Media made from manufacturers following the recipe above can be used after verification.