CDC study finds higher rate
for invasive MRSA infections
As this issue of AORN Management Connections neared completion, a flurry of newspaper headlines and broadcast media coverage generated by a new study estimating an alarming incidence rate for invasive methicillin-resistant Staphylococcus aureus (MRSA) infections was sure to focus attention on a conference to be held in Atlanta Nov. 5-6 sponsored by the Association for Professionals in Infection Control and Epidemiology, Inc. (APIC).
Titled MRSA: The Call to Action…1 Year Later, the APIC conference was to explore "new developments and strategies in the elimination of MRSA transmission." Joan Blanchard, RN, MSS, CNOR, CIC, a perioperative nursing specialist in AORN's Center for Nursing Practice who was to represent the association at the APIC conference, expected heightened media attention from the study, which was reported in the Oct. 17 issue of the Journal of the American Medical Association (JAMA) but stressed that the results of the study weren't surprising to healthcare professionals involved with infection control.
For example, results from an APIC survey of infection-control professionals released earlier this year yielded an estimate that 46 out of every 1,000 patients either were infected or colonized with MRSA—a rate that APIC said at the time was 8 to 11 times higher than previous estimates of MRSA's spread.
The study published in JAMA last month, which was billed as the first U.S. population-adjusted estimate of the burden of invasive MRSA based on active case data, was conducted by researchers at the federal Centers for Disease Control and Prevention (CDC) and at nine cooperating state departments of health or university public health programs. The study estimates a standardized incidence rate of invasive MRSA infections of 31.8 per 100,000 persons in calendar year 2005.
Most of the invasive MRSA cases (58.4%) occurred outside hospitals (community-onset infections) but occurred among persons with established MRSA risk factors, such as a history of hospitalization in the past year, a history of surgical procedures, long-term care residence or previous MRSA infection or colonization. Almost 30% of the MRSA cases were classified as "hospital-onset infections." The remaining cases were classified as "community-associated infections" (13.7%) or were not classifiable (1.3%).The study concluded that invasive MRSA is a major U.S. public health problem that is "primarily related to health care but no longer confined to acute care."
Blanchard said a significant finding of the CDC-authored study was its conclusion that "the general public now has as much to do with the spread of MRSA as hospitals"—i.e., that community-acquired and community-associated MRSA infections are as big a factor in the spread of MRSA as hospital-onset infections.
As "best-practice" resources for perioperative managers and infection-control specialists facing heightened concern over the threat of invasive MRSA infections, Blanchard cited guidelines issued last year by CDC for managing multidrug-resistant organisms, including MRSA, in healthcare settings. She also noted the availability of up-to-date guidance in related Clinical Issues columns in recent issues of AORN Journal and an article in the September 2007 issue of the AORN Journal titled: Perioperative Management of Multidrug-Resistant Organisms in Healthcare Settings.
After publication of the JAMA study, much of the media attention focused on scattered reports of MRSA outbreaks in schools nationwide. Acknowledging that concern, Blanchard cited a recent addition to CDC's Web site offering guidance on preventing skin infections that typify MRSA outbreaks in schools. The CDC guidance stresses 5 C's that are common factors in spreading such skin infections: Crowding, frequent skin-to-skin Contact, Compromised skin (i.e., cuts or abrasions), Contaminated items and surfaces, and lack of Cleanliness. Locations where the 5 C's are commonly found include schools, dormitories, military barracks, households, correctional facilities and daycare centers, CDC said.
The new CDC study's projection of 94,260 invasive MRSA cases in the U.S. in 2005 was far larger than a previous CDC estimate of 31,440 hospitalizations during 2000 for MRSA bacteremias. The earlier study used hospital discharge-coded data. The new study published in JAMA was based on 8,987 observed MRSA cases and 1,598 in-hospital MRSA-related patient deaths. The data was collected by nine CDC Emerging Infections Program surveillance sites that monitored invasive MRSA infections.
Data from the nine sites—which included the state of Connecticut, the metropolitan areas of Atlanta, San Francisco/Bay Area, Denver, and Portland, Ore., Monroe County, N.Y., Baltimore City, Davidson County, Tenn., and Ramsey County, Minn.—covered about 5.6% of the U.S. population. Projections for the overall U.S. incidence rate were obtained by combining U.S. Census data with surveillance site-specific age-, race- and sex-adjusted MRSA incidence rates.
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