Q&A: Cutting through the Hype around MRSAJUNE 30, 2008
Among health-related mainstream media stories, concern about the relative contagiousness and spread of methicillin-resistant Staphylococcus aureus (MRSA) has been reported on with increasing frequency in the last couple of years, particularly because MRSA can be fatal. MRSA is a strain of Staphylococcus aureus bacteria, typically referred to as "staph," that is resistant to the broad-spectrum beta-lactam antibiotics (e.g., cephalosporins, imipenem, and/or the penicillin derivatives methicillin, dicloxacillin, nafcillin, and oxacillin) commonly used to treat this microorganism.
Transmitted primarily through skin-to-skin, especially manual, contact as well as sharing items such as towels and razors, MRSA is more often associated with healthcare settings. That is, hospital-associated or healthcare-associated MRSA (HA-MRSA) is the more common category of MRSA because hospitals and other healthcare settings (e.g., nursing homes, dialysis centers, and ambulatory surgery centers as well as acute, intermediate or long-term acute care facilities) are home to many patients with open wounds, older adults and others with weakened or compromised immune systems. Hospital personnel that fail to follow proper sanitary procedures (e.g., hand hygiene) represent potential vectors of MRSA transmission from patient to patient.
MRSA has also had an impact in some public facilities, colleges, and secondary schools. Indeed, community-associated MRSA (CA-MRSA) has emerged in otherwise healthy individuals in the wider community. This form of MRSA has manifested as skin and soft tissue infections as well as pneumonia.
In our Q&A feature, Darren Linkin, MD, MSCE, Assistant Professor of Medicine at the Hospital of the University of Pennsylvania and the Philadelphia Veterans Administration Medical Center, Division of Infectious Disease, Assistant Professor of Epidemiology, University of Pennsylvania School of Medicine, Senior Scholar, Epidemiology, CCEB, and Ebbing Lautenbach, MD, MPH, MSCE, Associate Professor of Medicine, Infectious Diseases Division, and Associate Professor of Epidemiology, University of Pennsylvania School of Medicine, Associate Hospital Epidemiologist, Hospital of the University of Pennsylvania, Co-Director, Antimicrobial Management Program, Hospital of the University of Pennsylvania, Senior Scholar, Epidemiology, CCEB, discuss various aspects of MRSA infection.
Q: In March, you were interviewed by the Chicago Tribune in response to the results of a JAMA study that found the screening of surgical patients for MRSA not particularly effective, and a report published in the Annals of Internal Medicine by investigators at Evanston Northwestern Healthcare, which indicated that screening all hospital patients for MRSA can significantly lower the number of such hospital-acquired infections. How do explain the disparity of these results? Are the findings in either study generalizable to other health care settings?
EL: The discrepant results of these two studies emphasize the complexity of dealing with MRSA. There were several important differences between the studies. The JAMA study focused on a population of surgical patients at one Swiss hospital. The paper in the Annals of Internal Medicine focused on three hospitals in a Chicago area health system and included the entire hospital population. Strategies for screening for MRSA were similar across studies but the actions taken in response to a positive MRSA strain were different. Only in the Annals paper did a substantial proportion of subjects (about two thirds) receive decolonization (ointment administered to the nose to attempt to eradicate MRSA colonization). The primary take home message from the conflicting results of these studies is that the response to MRSA cannot be a "one size fits all" approach. The particular epidemiology of MRSA at a given institution, as well as the resources available, must be carefully considered when devising the optimal response.
Q: What is most important for the general public to understand regarding MRSA?
EL: While MRSA is an important pathogen, it has been a threat to the health of patients for decades. It is now more common in community settings, which makes it a greater threat to a larger proportion of the population. The most important thing to understand is that prevention of MRSA spread from person to person is best achieved by careful and consistent attention to personal hygiene, particularly hand washing. Since recent personal use of antibiotics has been associated with MRSA, using antibiotics only when necessary (e.g., not for a viral upper respiratory infection) is also important.
Q: Is healthcare MRSA more of a threat than community-associated MRSA?
DL: MRSA used to rarely cause community acquired infections, but the incidence has increased. Healthcare-associated and community-associated MRSA are genetically distinct, though now hospital-acquired infections can be with the typically community-associated MRSA strains and vice versa. Some community-acquired strains appear to be more virulent. In terms of quantifying a threat, one could say that the incidence of serious (e.g., life-threatening) HA-MRSA infections remains higher; CA-MRSA infections are more often less serious.
Q: What measures can be enacted to reduce or prevent the risk of contracting MRSA?
DL: Although the incidence of community-associated MRSA infections is rising, most people are not at risk of developing health- or life-threatening disease. Good hand hygiene is important in the community and the hospital settings. Unfortunately, hand hygiene in hospitals is often poor. While hospitals are working to improve hand hygiene and other practices internally, it's always important for patients and their families to be their own advocates, including asking healthcare workers caring for them whether they have cleaned their hands. Of course, more funding to study how to protect real patients from MRSA would be ideal, but this has not been a congressional priority. Asking your congressional representatives to support funding to study interventions to decrease the spread of MRSA and other resistant organisms may help increase this underfunded area.