Dr. Brad Spellberg MD
Associate Program Director
Internal Medicine Training Program
Professor of Medicine, David Geffen School of Medicine at UCLA, Division of General Internal Medicine
MedicalResearch: What are the main findings of the study?
Dr. Spellberg: The rates of community-onset methicillin-resistant Staphylococcus aureus (CO-MRSA) varied dramatically among academic medical centers in California, New York, Illinois and North Carolina, suggesting there is not a uniform change in the “national epidemic” of the “superbug” that has generated extensive public health concern over the past decade, according to a new study.The study surveyed hospital records of 4,171 cases of MRSA and MRSA-related infections between 2008 and 2011 in five medical centers located in Los
Angeles, San Francisco, Chicago, New York City and Raleigh-Durham, NC.The rates of MRSA acquired in the community declined 57% from 2008-2011 in
the Los Angeles medical center. In contrast, CO-MRSA rates tripled at the
New York medical center, while the rates remained stable in San Francisco,
Chicago and Raleigh-Durham.
MedicalResearch: Were any of the findings unexpected?
Dr. Spellberg: Using the same hospital data, the researchers found, the rates for a MRSA-related infection, methicillin-susceptible S. aureus (MSSA), tended to
change in the opposite direction from MRSA rates. Since MRSA and MSSA rates
moved in opposite directions, the authors concluded: “Enhanced infection
control efforts are unlikely to account for such variation in community
onset infection rates”
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Spellberg: In the mid-1990s, Los Angeles and Chicago were among the first regions in the country to be affected by the emergence of MRSA acquired in the
community. The “epidemic” of these community-acquired antibiotic-resistant
infections only recently reached New York, leading researchers to conclude
that the relatively stable incidence of CO-MRSA in Chicago and the decline
in Los Angeles will begin to be seen in East Coast cities in the near
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Spellberg: These dramatic differences in the incidence and rate of change in the number of MRSA and MSSA infections indicate ongoing, fundamental changes in bacterial ecology, which need further study to protect public health. Fully understanding MRSA, MSSA and other antibiotic-resistant infections is
to finding new approaches to save the lives and protect the health
of our patients here and around the world.
This study also found that more than half the MRSA cases involved the most
virulent form of the bacteria, bacterium with the USA300 genetic background.
But the incidence varied from 35% at one hospital to 80% at another. All
these differences in rates suggest that the epidemiology and other factors
of antibiotic resistance vary greatly, requiring further study to fully
understand antibiotic-resistant bacteria.
Citation:Staphylococcus aureus Bacteremia at Five U.S. Academic Medical Centers,
2008-2011: Significant Geographic Variation in Community-Onset Infections Michael Z. David, Robert S. Daum, Arnold S. Bayer, Henry F. Chambers, Vance G. Fowler, Jr., Loren G. Miller, Belinda Ostrowsky, Alison Baesa, Susan Boyle-Vavra, Samantha J. Eells, Sylvia Garcia-Houchins, Philip Gialanella, Raul Macias-Gil, Thomas H. Rude, Felicia Ruffin, Julia Sieth, Joann Volinski, and Brad Spellberg
Clin Infect Dis. first published online May 30, 2014 doi:10.1093/cid/ciu410