Thermo Scientific Limited has expanded its range of products for the growth and identification of methicillin resistant Staphylococcus aureus (MRSA) with the addition of a new Chromogenic Medium for screening of MRSA.

Thermo Scientific Chromogenic MRSA Agar (product code:P01091A UK/PO5083A other) has been specifically designed to screen clinical samples for the presence of MRSA, providing accurate, easy to read results in as little as 18 hours – up to 30 hours quicker than some alternative media that may require 48 hour incubations.

There is no need to re-incubate negative plates, making it a true next-day test.


The chromogen in Thermo Scientific Chromogenic MRSA Agar detects phosphatase activity (which is present in MRSA strains) producing distinct, easily visible, denim-blue colonies.

Fast and accurate screening is extremely important for infection control programmes to be effective. The speed of detection using Thermo Scientific Chromogenic MRSA Agar allows colonised patients to be targeted promptly for isolation and appropriate treatment, helping to minimise opportunities for transmission at the earliest opportunity. The accuracy of the new Thermo Scientific medium helps to ensure that costly resources are targeted towards those who need it, especially in hospitals where the MRSA rate is high.

The chromogen in Thermo Scientific Chromogenic MRSA Agar detects phosphatase activity, which is present in MRSA strains, producing distinct, easily visible, denim-blue colonies. Antimicrobial compounds within the medium, including cefoxitin, inhibit the growth of competitor organisms to allow accurate diagnosis of MRSA.

The medium may be inoculated directly from swabs, or from isolates or culture suspensions. The plate can then be examined for MRSA colonies after a short, 18-hour incubation.

In a comparative evaluation with four other commercially available chromogenic media and Oxacillin Resistance Screening Agar (ORSA), the Thermo Scientific Chromogenic MRSA Agar produced the best results at 18 hours and gave excellent colour differentiation [1].
For further information about Thermo Scientific Chromogenic MRSA Agar, please contact Carlene Simmons [details above] or click on the link below.

Reference:
1. Hutchinson, M. J., Edwards, G. F. S., Morrison, D., “Evaluation of chromogenic MRSA selective screening media,” poster by Scottish MRSA Reference Laboratory presented at the 2005 Institute of BioMedical Sciences Annual Conference.