Oxford Modified Agar Base, Selective Supplement

The addition of a supplement containing antimicrobial agents to Oxford Modified Agar Base, is used to promote the selective cultivation and isolation of Listeria spp.

Purpose

The addition of antimicrobial agents to “Oxford Modified Agar Base” allows the selective isolation of Listeria spp, because they inhibit totally or partially the growth of the accompanying flora present in the test sample other than Listeria spp.

Formula (in grams per liter)		Instructions
Colistin	0.005	Aseptically add 2.1 ml of sterile distilled water to the content of one vial of this supplement. Then, add 2 ml of the vial content to 500 ml of sterile, melted and cooled to 50 ºC Oxford Modified Agar Base. Mix well and pour into sterile Petri dishes.
Ceftazidime	0.01

Each vial is useful to add into 500 ml of culture medium.

Inoculation

Directly, streak on the surface of the agar.

Incubation

At 35-37 ºC, for 24-48 hours in atmosphere with 5-10% % CO2.

Results

Organisms	Growth	Colonial Characteristics
Listeria monocytogenes ATCC 19114	Good	Small black colonies, with black haloes against amber background
Listeria ivanovii ATCC 19119	Good	Small black colonies, with black haloes against amber background
Escherichia coli ATCC 25922	Inhibited	----------
Enterococcus faecalis ATCC 29212	Inhibited	----------
Proteus mirabilis ATCC 43071	Inhibited	----------

Appearance

White coloured powder.

Storage:

Keep between 2-8 ºC.

Packaging
3 vials per 0.015 g	Code:  B03-617-21