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Brilliance VRE AGAR

Code: PO1175

BrillianceVRE Agar is a chromogenic screening plate for the detection of Vancomycin Resistant Enterococci (VRE). The medium provides presumptive identification of Enterococcus faecium and Enterococcus faecalis, direct from clinical samples in 24 hours.

Only available in certain territories. Please speak to your local Oxoid supplier.

Typical Formula*gm/ litre
Peptone mix 25
Salt mix 12
Agar12.5
Titanium dioxide1
Chromogenic mix 0.45
Antibiotic cocktail (including vancomycin) 5ml
pH 6.5 ± 0.2 @ 25 ºC  

* Adjusted as required to meet performance standards

Description
Vancomycin-resistant enterococci (VRE) have recently emerged as nosocomial pathogens, due to the increased use of vancomycin for treatment of meticillin-resistant Staphylococcus aureus in the United States of America and use of a vancomycin-like glycopeptide (avoparcin) as a growth promoter in animal husbandry in Europe1.

In the U.S.A., the Centers for Disease Control and Prevention reported that as many as 1 in 3 infections among intensive care patients were caused by VRE2. Early detection of VRE is important for infection control and prevention measures, epidemiological infectious disease follow-up, and also prevention of vancomycin resistant Staphylococcus aureus emergence3.

The importance of screening as part of an effective infection control programme to limit the spread of VRE is well recognised. Speed and accuracy of results are critical aspects of this. Colonised patients can be accurately targeted for isolation and appropriate treatment as early as possible. Resource is not wasted on patients who are not colonised.

A variety of media are used to screen for VRE. These include Bile Aesculin Azide agar and Enterococcosel™ agar, both supplemented with vancomycin. Most of these traditional media have issues of sensitivity or specificity, all require up to 48 hours incubation and some need broth pre-enrichment. Traditional media can not differentiate between E. faecium and E. faecalis, the two predominant strains of VRE, or the intrinsically resistant (VanC) organisms, E. gallinarum and E. casseliflavus. These VanC organisms, although resistant to vancomycin, are deemed less clinically significant and are rarely associated with transmission or hospital outbreaks4.

In recent years, VRE screening technology has improved with chromgenic media becoming available for the detection of VRE. While sensitivity of these chromogenic media is higher than that of tradition media, most still require 48 hours incubation to detect certain VanB VRE strains.

Oxoid Brilliance VRE Agar utilises a novel formulation for the recovery and detection of VRE, including VanB isolates, which are especially difficult to culture, ensuring that even these slower growing strains are detectable at 24 hours on Brilliance VRE Agar.

Brilliance VRE Agar can be inoculated directly from a screening swab, isolated colony or liquid suspension. VRE grow as either light blue colonies (E. faecalis) or as indigo-purple colonies (E. faecium), both of which are very easy to read against the new, semi-opaque background. Plates are incubated at 37ºC, and provide high sensitivity and specificity, with results available in just 24 hours. This allows a rapid response from infection control teams and enables the patient to receive the most appropriate treatment, as early as possible. Accuracy minimises costs, by helping to ensure that only those in need receive what can be costly treatment.

Technique
Brilliance VRE Agar can be inoculated direct from faecal screening swabs, faecal sample, isolated colony or from liquid suspension, according to local guidelines. The medium should be allowed to warm to room temperature before inoculation. Incubate for 18-24 hours at 37ºC. Negative plates may be re-incubated for an additional 24 hours. Light blue colonies are presumptive positive for VRE E. faecalis and indigo-purple colonies for VRE E. faecium.

Identifications can be confirmed using Oxoid Streptococcus Grouping Kit (DR0585 -Lancefield group D) and O.B.I.S. PYR (ID0580) direct from the plate, or if sub-cultured on to a suitable medium, RapID STR can be used to confirm speciation. For an accurate determination of the vancomycin minimum inhibitory concentration Vancomycin M.I.C.Evaluator™ Strips (MA0102), may be used but only from a suitable AST media.

For further instructions on the use and interpretation of Brilliance VRE Agar, simply download the data sheet (770KB) in PDF format.

Storage conditions and shelf life
Brilliance VRE Agar plates should be stored in the original packaging at the temperature stated on the pack or product specification, and protected from direct light. When stored as directed, the unopened product will remain stable until the expiry date on the label.

Appearance
Prepared medium: Pale, off-white, semi-opaque gel medium in Petri dishes

Quality Control

Positive ControlsExpected results
Enterococcus faecalis (VRE) ATCC®51299Good growth: light blue colonies
Enterococcus faecalis (VRE) ATCC®12201Good growth: light blue colonies
Enterococcus faecium (VRE) ATCC®12202Good growth: indigo/purple colonies
Negative Controls 
Enterococcus faecalis ATCC®35667Inhibited
Enterococcus faecium ATCC®19433Inhibited
Enterococcus gallinarum ATCC®700425Inhibited

Precautions
Brilliance VRE Agar is for in vitro diagnostic use only, by trained individuals. Do not use beyond the expiry date given on the label, or if the product shows any sign of deterioration.
Sterilise specimens, equipment and media properly after use.

Limitations
Samples containing faecal material or blood may cause some localised discolouration within the medium this discolouration should not be confused a true chromogenic reaction were coloured colonies are visable.

References

1. Bell J.M., Paton J.C., Turnidge J. (1998). Emergence of Vancomycin Resistant Enteroccocci in Australia: Phenotypic and Genotypic Characteristic of Isolates. J. Clin. Microbiol. 36, 2187-2190.
2. Centers for Disease Control and Prevention (2006). Recommendations for Preventing the Spread of Vancomycin Resistance: HICPAC.
3 Delmas J., Robin F.,Schweitzer C., Lesens O., Bonnet R. (2007). Evaluation of a new chromogenic medium, chromID VRE, for detection of Vancomycin Resistant Enterococci in stool samples and rectal swabs. J. Clin. Microbiol. 45, 2731-2733.
4. Werner G., Coque T.M., Hammerum A.M., Hope R., Hryniewicz W., Johnson A., Klare I., Kristinsson K.G., Leclercq R., Lester C.H., Lillie M., Novais C., Olsson-Liljequist B., Peixe L.V., Sadowy E., Simonsen G.S., Top J., Vuopio-Varkila J., Willems R.J., Witte W., Woodford N. (2008) Emergence and spread of vancomycin resistance among enterococci in Europe. Eurosurveillance, 13, 1-10.

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