OXFORD-LISTERIA-SELECTIVE-AGAR (BASE)

General description

GranuCult^® Oxford Agar (Base) formulation is based on Columbia Agar with the addition of lithium chloride, acriflavin, colistin sulfate, cefotetan, cycloheximide, and fosfomycin. These ingredients suppress the growth of the common bacteria (e.g., Gram-negative bacteria and a greater part of Gram-positive bacteria). Lithium chloride is one of the ingredients of Oxford Agar base, while the other substances are derived from the Oxford Listeria Selective Supplement (1.07006). Listeria monocytogenes hydrolyses esculin to esculetin and forms a black complex with iron (III) ions, thereby producing brown-green colored colonies with a black halo.

Application

GranuCult^® Oxford Agar (Base) is a selective agar for the isolation and detection of Listeria monocytogenes in milk and milk products and other food products.

Analysis Note

Base tested with Oxford-Listeria-selektiv-supplement art. no. 1.07006.
Appearance (clearness): clear
Appearance (color): blueish-brown to greenish-brown
pH-value (25 °C): 6.8 - 7.2
Growth promotion test in accordance with the current version of DIN EN ISO 11133.
Inoculum on reference medium (Listeria monocytogenes ATCC 35152 (WDCM 00109)):
Inoculum on reference medium (Listeria monocytogenes ATCC 13932 (WDCM 00021)):
Inoculum on reference medium (Listeria innocua ATCC 33090 (WDCM 00017)):
Colony count (Listeria monocytogenes ATCC 35152 (WDCM 00109)):
Colony count (Listeria monocytogenes ATCC 13932 (WDCM 00021)):
Colony count (Listeria innocua ATCC 33090 (WDCM 00017)):
Recovery on test medium (Listeria monocytogenes ATCC 35152 (WDCM 00109)): ≥ 50
Recovery on test medium (Listeria monocytogenes ATCC 13932 (WDCM 00021)): ≥ 50
Recovery on test medium (Listeria innocua ATCC 33090 (WDCM 00017)): ≥ 50
Growth Escherichia coliATCC 25922 (WDCM 00013): total inhibition
Growth(Escherichia coli ATCC 8739 (WDCM 00012)): total inhibition
Growth (Staphylococcus aureus ATCC 25923 (WDCM 00034)): partial inhibition
Growth (Candida albicans ATCC 10231 (WDCM 00054)): partial inhibition
Black zone (Listeria monocytogenes ATCC 35152 (WDCM 00109)): black zone
Black zone (Listeria monocytogenes ATCC 13932 (WDCM 00021)): black zone
Black zone (Listeria innocua ATCC 33090 (WDCM 00017)): black zone
Incubation: up to 48 hours at 35 ± 1 °C, aerobic
A recovery rate of 50 % is equivalent to a productivity value of 0.5.
The indicated colony counts result from the sum of a triple determination.
Reference media: Tryptic Soy Agar

Footnote

We offer two media types: the superior granulated GranuCult^® and the cost-efficient powdered NutriSelect^® culture media, depending on your needs.
The designations basic, plus, or prime are added to indicate the quality control level, from basic quality control to standard QC plus to prime for full regulatory compliance.

Legal Information

GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany

NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany