Listeria Oxford Medium Base ( M1145 )
Intended use
Recommended for isolation of Listeria species from pathological specimens.
*Composition**
Ingredients Gms / Litre
Peptone, special 23.000
Lithium chloride 15.000
Sodium chloride 5.000
Corn starch 1.000
Esculin 1.000
Ammonium ferric citrate 0.500
Agar 10.000
Final pH ( at 25°C) 7.0±0.2
**Formula adjusted, standardized to suit performance parameters
Directions
Suspend 27.75 grams in 500 ml purified / distilled water. Heat to boiling to dissolve the medium completely. Sterilize by
autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C and aseptically add the rehydrated contents of 1 vialof Oxford Selective Supplement (FD071) or 1 vial of CM Selective Supplement (FD126). Mix well before pouring into sterile Petri plates.
Quality Control
Appearance
Light yellow to dark yellow homogeneous free flowing powder
Gelling
Firm, comparable with 1.0% Agar gel.
Colour and Clarity of prepared medium
Dark amber coloured clear to slightly opalescent gel with a blue cast forms in Petri plates
Reaction
Reaction of 5.55% w/v aqueous solution at 25°C. pH : 7.0±0.2
pH
6.80-7.20
Cultural Response
Cultural characteristics observed with added Oxford Selective Supplement (FD071) or CM Selective Supplement (FD126),after an incubation at 35-37°C for 24-48 hours.
Storage and Shelf Life
Store between 10-30°C in a tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the
label.