For Infection Control Professionals – About Infection Control
The CDC demonstrated in 2005 that the vast majority of MRSA infections have their onset in the community. Our Dallas County Jail (Texas) Study and our Household Contacts Study attempt to further our understanding.
Methicillin-resistant Staphylococcus aureus (MRSA) has been a challenge for infection control practitioners for decades. As the epidemiology of MRSA has shifted with the emergence of community-associated (CA-) MRSA strains, in the late 1990s, particularly in North America, this challenge has become more complex.
Although most individuals with invasive MRSA infections have had previous exposure to health care facilities, the Centers for Disease Control and Prevention (CDC) demonstrated that in 2005, the vast majority of these infections have their onset in the community rather than in hospitals or other health care facilities. USA300, the most common clonotype of CA-MRSA in the U.S., has become an important nosocomial pathogen in several large medical centers, further complicating the molecular epidemiology of MRSA in the health care setting. It is not known if the results of studies of health care associated (HA-) MRSA strains in the health care setting are applicable to USA300. Therefore, programs aimed at MRSA control in the health care setting must take into account the local epidemiology of MRSA outside of the health care institution as well as the changing epidemiology of MRSA in the health care setting.
While the primary means of infection control to contain MRSA in U.S. hospitals has been contact precautions (i.e., the use of gowns and gloves), many new potential interventions and screening procedures have been suggested and tested in a limited number of hospitals. For example, a law in Illinois now requires that all patients admitted to intensive care units be screened for asymptomatic carriage of MRSA, although the method used for this screening is not specified. Some infection control practitioners have advocated that all patients found to be colonized or infected with MRSA should undergo decolonization procedures (e.g., nasal mupirocin, chlorhexidine baths). Further research is needed to evaluate each of these proposed interventions.
Infection surveillance programs, hand hygiene compliance, and contact precautions remain the most effective known containment strategies for the spread of MRSA within the health care setting. To optimize infection control strategies, more research is needed to define the transmissibility of USA300 and other CA-MRSA strains in the community and in the health care system, the role of fomites (inanimate objects and surfaces) in transmission, the role of health care institutions in the epidemiology of MRSA, and the efficacy of decolonization protocols.
Michael Z. David, MS, MD, PhD
Instructor, Section of Infectious Diseases, Department of Medicine
MRSA Research Center
University of Chicago Medical Center
The views on this page are of the MRSA Research Center, not necessarily those of the institutional infection control program at the University of Chicago Medical Center.