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Brilliance ESBL Agar Datasheet

Brilliance ESBL AGAR

Code: PO5302

Brilliance™ ESBL Agar is a chromogenic screening plate for the detection of Extended Spectrum β-Lactamase-producing organisms. The medium provides presumptive identification of ESBL-producing E. coli and the Klebsiella, Enterobacter, Serratia and Citrobacter group (KESC), direct from clinical samples, in 24 hours.

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

Typical Formula*

gm/litre

Peptones

12.0

Sodium chloride

5.0

Phosphate buffers

4.0

Chromogenic mix

4.0

Antibiotic mix

0.28

Agar

15.0

* Adjusted as required to meet performance standards

Description
Extended Spectrum Beta-Lactamase producing organisms have recently emerged as nosocomial pathogens.

ESBLs are defined as tranferrable enzymes able to hydrolise third and fourth-generation cephalosporins but which may be inhibited by clavulanic acid. Unlike MRSA or VRE, the resistance mechanisms of ESBLs are not limited to one or even two species but rather a whole family of organism, the Enterobacteriaceae. Enterobacteriaceae have become one of the most important causes of nosocomial and community-acquired infections. The main therapeutic choices to treat such infections are β-lactam antiobiotics (mainly broad spectum penicillins and cephalosporins). The lack of treatment options combined with the transmissible nature of ESBL resistance mechanisms and the alarming rate at which they have spread, results in a significant threat to global public health.

The presence of an ESBL infection severely limits treatment options as the resistance mechanisms confer wider resistance than AmpCs, which may still be treated with certain β-lactamase-stable antibiotics. In addition to this, ESBL resistance genes are encoded on freely transmissible genetic elements, greatly increasing the risk of spread to other organisms.

Further information is available in an article "The new MRSA?" which first appeared in Health: Issue 24, in 2010.

Traditional culture-based screening is labour-intensive and time consuming, relying on antimicrobial susceptibility testing (AST) against a range of β-lactam antibiotics. Cefotaxime and ceftazidime have been found to be good markers for ESBL-expression1. Some culture media have been designed to exploit the organism’s resistance to one or both of these antibiotics. For example, a bi-plate format comprising Drigalski Agar+cefotaxime and MacConkey Agar+ceftazidime for the presumptive identification of ESBL-producing, or multi-drug resistant, Gram-negative organisms has been available from some manufacturers. The bi-plate format is rather awkward and requires double inoculation.

In recent years, ESBL screening technology has improved with a number of chromgenic media available for the detection of ESBL. While sensitivity of these chromogenic media is higher than that of tradition media, most still require 48 hours incubation to detect certain resistance mechanisms. Selectivity is often an issue, especially with certain AmpC possessing organisms.

Oxoid Brilliance ESBL Agar utilises a novel formulation which enhances the selectivity of the medium for the selective inhibition of AmpC resistance mechanisms, while maintaining a high degree of sensitivity for the detection of ESBL producing Enterobacteriaceae. Brilliance ESBL Agar can be inoculated from a screening swab taken from hospital patients, from an isolated colony or from a liquid suspension. ESBL-producing E. coli grow as either blue or pink colonies. ESBL-producing members of the KESC group produce green colonies; Proteus, Morganella and Providencia do not utilise either chromogen, but are able to deaminate tryptohan, resulting in tan colonies with a brown halo.

Colony colours are particularly 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 ESBL Agar can be inoculated direct from rectal screening swabs, faecal samples or from an isolated colony prepared as a liquid suspension approximately equivalent to 0.5 McFarland turbidity, according to local guidelines. Isolated colonies should not be directly plated onto Brilliance ESBL Agar, as the high level of inoculum is likely to cause false positive results. The medium should be allowed to warm to room temperature before inoculation. Incubate for 18-24 hours at 37ºC. Negative plates should be re-incubated for an additional 24 hours. Blue or pink colonies are presumptive positive for E. coli ESBLs and green colonies for KESC group ESBLs. Proteus, Morganella and Providencia produce tan colonies with a brown halo. E. coli identifications can be confirmed using RapID™ Spot Indole test (R8309002) or if sub-cultured on to a suitable medium RapID™ One can be used to confirm speciation.

For further instructions on the use and interpretation of Brilliance ESBL Agar, simply download the data sheet (1.60MB) in PDF format.

Storage conditions and shelf life
Brilliance ESBL 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 Controls

Expected results

Klebsiella pneumoniae SHV-18 ATCC® 700603

1 - 2 mm, green colonies

Escherichia coli TEM-3 NCTC 13351

1 - 2 mm; blue colonies

Negative controls  
Enterobacter cloacae ATCC® 23355

Complete inhibition

Citrobacter freundii NCTC 8581

Complete inhibition

Candida albicans ATCC® 10231

Complete inhibition


Precautions
Brilliance ESBL 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 where coloured colonies are visible. 

It should be noted that, as with all chromogenic media, organisms with atypical enzyme patterns may give anomalous reactions on Brilliance ESBL Agar.

References

1. H. K. Geiss, (1990) Comparison of two test kits for rapid identification of Escherichia coli by a beta-glucuronidase assay. European Journal of Clinical Microbiology & Infectious Diseases; 9 (2):151-152


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