364. Temporal and Spatial Persistence of MRSA strains in Community Settings
Session: Poster Abstract Session: MRSA, MSSA, Enterococci
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background:

Methicillin-Resistant Staphylococcus aureus (MRSA) causes considerable morbidity and mortality throughout the United States.  From March 2009 through February 2010, all MRSA isolates were prospectively collected from 7 community hospitals across Ohio (located 30 – 120 miles from an academic medical center) allowing comparison of rep-PCR strain types over time and between hospitals. This analysis focused on characterizing predominant strain types as well as assessing strain pattern homogeneity between hospitals. 

Methods:

During the study period,  MRSA specimens from the community hospitals were prospectively collected for genotyping using repetitive element PCR (rep-PCR) with arbitrary number classification of individual types with rep-PCR types matched to corresponding PFGE and SCCmec genotypes in the DiversiLabTM library.  MLST and spa typing were also obtained on selected isolates.  Rep-PCR types were plotted over time for each community hospital in order to visualize the temporal trends occurring at each location and to facilitate comparison of trends between hospitals.   

Results:

There were a total of 397 isolates genotyped.  Rep-PCR type 9 isolates predominated at each hospital from 3/2009 through 9/2009 and disappeared by 10/2009. They comprised 28.2% (112/397) of isolates overall. rep-PCR type 9 corresponded to SCCmec type IVa and PFGE type 300 in the DiversiLabTM library with 94.6% (106/112) cases identified as community associated. By 12/2009, rep-PCR type 63 became the predominant strain for six of the seven hospitals, and comprised 17.1% (68/397) of isolates overall.  Rep-PCR type 63 was associated with SCCmec type IVb and PFGE type 300 in the DiversiLabTM library with 95.6% (65/68) of cases identified as community associated.  Different healthcare associated (HA) rep-PCR strains, although introduced intermittently, typically failed to persist longer than a month. These strains tended to appear at similar times across the seven hospitals.  

Conclusion:

The 7 community hospitals exhibited very similar MRSA strain patterns despite large geographic distances, with two different community associated strains predominating at different times. While present, HA strains failed to become established. A better understanding of factors contributing to strain longevity is needed.

Kristin Mccarthy, BS, MS, Epidemiology, College of Public Health, The Ohio State University, Columbus, OH, Lisa Hines, RN, CIC, The Ohio State University Wexner Medical Center, Columbus, OH, Yosef Khan, MBBS, MPH, PhD, Biomedical Informatics, Ohio State University Medical Center and College of Medicine, Columbus, OH, Preeti Pancholi, PhD, Clinical Microbiology, The Ohio State Univ Med Ctr, Columbus, OH, Shu-Hua Wang, MD, MPH&TM, Internal Medicine, Ohio State University Medical Center, Columbus, OH and Kurt Stevenson, MD, MPH, Ohio State University Wexner Medical Center, Columbus, OH

Disclosures:

K. Mccarthy, None

L. Hines, None

Y. Khan, None

P. Pancholi, None

S. H. Wang, None

K. Stevenson, None

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