New Medium Enhances MRSA Screening

A new broth medium for the quick and easy screening of clinical samples for the presence of methicillin staphylococcus aureus (MRSA) saves time and resources by enabling a laboratory to screen out negative samples.

The new medium, from Oxoid (Basingstoke, UK), is called Selective Monnitor Broth. Samples from patients and hospital staff can be simply inoculated into vials containing 5 ml of the medium and then incubated overnight. Selective agents within the medium are designed to inhibit the growth of other organisms, while permitting the MRSA to grow. MRSA is able to ferment the mannitol in the broth, which acidifies the medium, causing the color to change from red to yellow and giving a presumptive positive reaction. All the negative broths can be discarded, while confirmatory tests are performed on isolates from the positive broths.

Multiple samples from an individual can be pooled, reducing the number of tests required. The ability to screen out negative cultures reduces the number of confirmation tests required. A recent review of MRSA isolation policies concluded that it should be possible to eradicate an endemic MRSA problem with an effective isolation policy, over time. In addition, such a policy could result in cost savings by reducing the length of stay in the hospital. The new medium contributes to an effective isolation policy by providing a fast and efficient method for screening clinical samples for MRSA.




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