Surveillance is a critical component of any program for controlling multi-drug resistant organisms (MDROs). Many institutions use active surveillance cultures to identify patients who are colonized with a targeted MDRO. With respect to MRSA, an increasing number of hospitals screen patients upon admission and on a periodic basis (usually weekly). The anterior nares is the primary site that is swabbed for screening.
Chromogenic agars have been developed for the isolation and presumptive identification of different species of bacteria and yeast. The media are formulated so that as different organisms utilize various substrates in the media, the organism of interest produce colonies with a unique color. For MRSA, depending on the manufacturer's instructions, the colors produced are sometimes described as either mauve or denim blue. Chromogenic agars specifically designed for the detection of MRSA are commercially available and used in most clinical laboratories.
In addition to culture methods, there are now commercially available, FDA-approved methodologies for screening for MRSA by PCR. Although equipment and cost factors may not make these a viable option for every laboratory, they may offer greater sensitivity and improved turnaround times.
