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Screening for MRSA Using PCR

Fewer patients in the rapid-testing group than in the conventional-culture group acquired MRSA, but the difference was not significant.

Compared with methicillin-sensitive Staphylococcus aureus infections, methicillin-resistant S. aureus (MRSA) infections are associated with higher mortality, morbidity, and costs. Thus, preventing MRSA acquisition is a top priority at many hospitals. One preventive approach is screening at admission for MRSA using rapid PCR testing, which can detect MRSA within 1 day, as opposed to the 2 to 3 days necessary for conventional cultures; earlier detection could lead to earlier implementation of control measures (e.g., strict isolation). In this trial, investigators assessed whether universal screening with rapid PCR testing leads to lower MRSA acquisition rates among hospitalized patients.

Ten wards at a London hospital were randomized to provide either rapid testing or conventional-culture screening. After initial treatment and washout periods, each ward crossed over to the other method. Complete data were available for nearly 7000 patients. The median time from admission to results reporting was significantly shorter for rapid testing (22 hours) than for conventional culture (46 hours). Furthermore, rapid-testing patients spent significantly fewer days inappropriately isolated than did conventional-culture patients (277 vs. 399 days). Although fewer patients in the rapid-testing group (2.8%) than in the conventional-culture group (3.2%) acquired MRSA, this difference was not significant.

Comment: Using rapid PCR testing for universal MRSA screening of hospitalized patients provides results more quickly and leads to less use of inappropriate control measures. However, this approach did not reduce MRSA acquisition in this study, and results have been mixed in other recent studies (Journal Watch Mar 11 2008 and Mar 25 2008). Notably, rapid PCR tests are expensive, and savings from less use of inappropriate control measures could be offset by the costs of rapid testing.

— Paul S. Mueller, MD, MPH, FACP

Published in Journal Watch General Medicine May 13, 2008

Citation(s):

Jeyaratnam D et al. Impact of rapid screening tests on acquisition of meticillin resistant Staphylococcus aureus: Cluster randomised crossover trial. BMJ 2008 Apr 26; 336:927.

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