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BRILLIANCE LISTERIA AGAR BASE

Code: CM1080

Brilliance™ Listeria Agar (formerly Oxoid Chromogenic Listeria Agar (OCLA)) is a medium for isolation, enumeration and presumptive identification of Listeria species and Listeria monocytogenes from food samples.

Typical Formula*

gm/litre

Peptone
18.5

Yeast extract

4.0
Sodium chloride
9.5
Sodium pyruvate
2.0
Lithium chloride
15.0
Maltose
4.0
X-glucoside chromogenic mix
0.2

Agar

14.0

pH 7.2 ± 0.2 @ 25°C

 
*Adjusted as required to meet performance standards

BRILLIANCE LISTERIA SELECTIVE SUPPLEMENT

Code: SR0227

Typical Formula

SR0227E
(1 vial per 500ml
medium)

per litre
Nalidixic acid

13.0mg

26.0mg
Polymyxin B

5.0mg

10.0mg

Ceftazidime

3.0mg

6.0mg

Amphotericin

5.0mg

10.0mg


BRILLIANCE
LISTERIA
DIFFERENTIAL SUPPLEMENT

Code: SR0228

Typical Formula

SR0228E
(1 vial per 500ml
medium)

per litre
Lecithin solution

20.0ml

40.0ml


Brilliance
Listeria Agar is the isolation medium used in the Oxoid Listeria Precis™ rapid culture method. For more information simply download the Brilliance Listeria Agar data sheet (946KB) or the Listeria Precis data sheet (680KB) in PDF format.

Directions
Suspend 33.6g of Brilliance Listeria Agar Base (CM1080) in 480ml of distilled water. Mix well and sterilize by autoclaving at 121°C for 15 minutes. Cool the medium to 46°C and add one vial of Brilliance Listeria Selective Supplement, reconstituted as directed and one vial of Brilliance Listeria Differential Supplement. Mix well and pour into sterile Petri dishes.

Description
Listeria monocytogenes is the most common pathogenic Listeria spp. and has been shown to be pathogenic to both man and animals. Some Listeria ivanovii strains also possess lecithinase activity and, although Listeria ivanovii are primarily pathogenic to animals, there are strains which have been shown to cause infection in humans3. Studies have shown this medium to be superior to PALCAM or Oxford medium for the isolation of Listeria monocytogenes4.

Brilliance Listeria Agar uses the chromogen X-glucoside for presumptive identification of Listeria spp. This chromogen is cleaved by ß-glucosidase which is common to all Listeria species. Other organisms that possess this enzyme, such as enterococci, are inhibited by the selective agents within the medium; lithium chloride, polymyxin B and nalidixic acid, whilst amphotericin inhibits the growth of any yeasts and moulds present in the sample. Listeria monocytogenes and pathogenic Listeria ivanovii are then further differentiated by their ability to produce the phospholipase enzyme, lecithinase. This enzyme hydrolyses the lecithin in the medium, producing an opaque white halo around the colony.

Brilliance Listeria Agar is a modification of the formulation described by Ottaviani and Agosti2. As in the original formulation, the medium is designed to identify Listeria spp. based on their utilisation of a chromogenic substrate. However, in this modification, the pathogenic Listeria spp. are then further differentiated by the detection of lecithinase (phosphotidylcholine phospholipase C (PCPLC) activity, rather than phosphotidylinositol phospholipase C (PIPLC) activity. Both enzymes, PCPLC and PIPLC, are associated with virulence in Listeria spp., and, therefore, the presence of either enzyme is a useful indicator of pathogenicity.

Technique
Brilliance Listeria Agar can be used following a variety of enrichment procedures i.e. ISO, NMKL, BAM, etc. The following is a suggested protocol using ONE Broth-Listeria. This method has been validated by AFNOR and been shown to give equivalent results to ISO 11290-1:19971,5.

  1. Add 25g of food sample to 225ml of ONE Broth-Listeria (CM1066 & SR0234) and stomach for a minimum of 30 seconds to mix the sample.
  2. Incubate the broth without agitation at 30ºC for 24 ± 2 hours.
  3. Gently agitate the bag then, using a microbiological loop, remove 10µl and inoculate onto an Brilliance Listeria Agar plate and incubate at 37ºC for 24 ± 2 hours. Examine the plate for blue colonies with and without opaque white halos.
  4. When testing meat samples, incubate negative plates for a further 24 ± 2 hours and examine again.
  5. Confirm presumptive colonies on the agar plate as Listeria monocytogenes or Listeria species by appropriate methods e.g. Gram stain, catalase, Oxoid O.B.I.S. mono ID0600M, Oxoid Listeria Latex Test Kit DR1126A, Microbact Listeria 12L MB1128A.

Storage conditions & Shelf life
The dehydrated medium should be stored at 10-30°C and used before the expiry date on the label.
Prepared medium may be stored for up to 2 weeks at 2-8°C.

Appearance:
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Translucent, white gel

Quality control

Positive controls:

Expected results

Listeria monocytogenes ATCC®7644 *Good growth; blue/green colonies with haloes
Listeria innocua ATCC®33090 *Good growth; blue/green colonies with no halo
Negative contol: 
Enterococcus feacalis ATCC®29212 *Inhibited
* This organism is available as a Culti-Loop®

Reference
1.
Oxoid Folio No. 1059.
2. Ottaviani, F., Ottaviani, M. and Agosti, M. (1997) Quimper Froid Symposium Proceedings, P6 A.D.R.I.A. Quimper (F) 16-18 June
3. Cummins, A.J., Fielding, A.K. and McLauchlin, J. (1994) Listeria ivanovii infection in a patient with AIDS. Journal of Infection
28, p89-91
4. Data on file at Oxoid.
5. ISO 11290-1:1997 Horizontal method for the detection and enumeration of Listeria monocytogenes Part 1: Detection Method.

 
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