MRSA Molecular Testing

Infections that patients acquire during treatment in a healthcare setting have become a topic of news headlines across the country. It is estimated that each year, 1.7 million individuals in the United States acquire such infections—commonly referred to as healthcare-associated infections (HAIs)—and 8% of these infections are caused by methicillin-resistant Staphylococcus aureus, or MRSA (Diekema and Climo 2008).

MRSA is virulent and difficult to treat. It is transmitted in the healthcare setting at a rate that has been rising rapidly in recent years: The proportion of intensive care unit S. aureusinfections that are attributable to a MRSA strain grew from 22% in 1995 to 64% in 2004 (CDC 2007). In fact, some experts consider MRSA to be endemic in the U.S. population. For these reasons, controlling the spread of MRSA has become a top priority among clinicians, health officials, and the general public.

The pressure to eradicate MRSA infections is growing. Last fall, the Centers for Medicare & Medicaid Services (CMS) indicated that it would no longer reimburse hospitals for the treatment of certain preventable injuries occurring during a patient’s stay, including certain HAIs such as catheter-related urinary tract and bloodstream infections. CMS has since added certain surgical-site HAIs to the list of unreimbursed conditions. In addition, states have passed legislation requiring public reporting of HAIs and/or reporting of MRSA infections in particular. At the federal level, legislation (the MRSA Infection Prevention and Patient Protection Act) was introduced in the Senate in December 2007 that would require all hospitals to institute policies and procedures as defined by the U.S. Department of Health and Human Services to reduce MRSA infections.

In response to these pressures and the need to address what is viewed as a growing healthcare problem, some hospitals are setting up screening programs (also referred to as active surveillance programs) to identify MRSA-colonized individuals coming into or already present in their facilities. In fact, a few states have begun requiring such programs. However, for facilities that have a choice in the matter, implementation of such a program should not necessarily be viewed as a matter of course; while such a program can have patient safety and even financial benefits, the decision requires careful consideration of a number of factors. (See the discussions “To Screen or Not to Screen?” and “Screening May Be Expensive, but It’s Cheaper Than Treatment” below. )

If a facility chooses or is required to perform screening, it must then decide what type of testing technology to use. There are two basic ways to test for MRSA colonization: molecular-based testing and culture testing. This Evaluation focuses on molecular testing; however, for facilities that are...