471. Community- and Healthcare-associated Staphylococcus aureus in an Integrated Healthcare Network in Salt Lake City, UT, 2001-2008: Is the Epidemic Abating?
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: The evolving pandemic of community-associated (CA) methicillin-resistant (MR) Staphylococcus aureus (SA) has been reported to be seeding entry of new strains of MRSA into hospital environments, with concern that more virulent strains of CA-MRSA might lead to increases in healthcare-associated (HA) MRSA infections in both hospitals and communities. Multiple reports have documented hospital outbreaks of HA-MRSA , but generally have not defined incidence rates of HA-MRSA. We sought to define rates of CA- and HA-MRSA as an indicator of the impact of CA- MRSA on incidence rates of HA-MRSA.
Methods: We examined the electronic medical records of 4,154,901 patient encounters from four hospitals and associated outpatient (OP) clinics and emergency departments (ED) to identify inpatients (IP), OP, and ED patients with positive SA cultures between January 1, 2001 and December 31, 2008. We categorized isolates as CA (ER, OP, isolates collected<48 hours after admission, or HA (collected >48 after admission, healthcare exposure preceding year). We reported incidence rates by year as isolates/10,000 total, CA or HA patient encounters. We performed trend analysis using S-statistics.
Results: Over the 8 year period we identified a total of 22,410 SA isolates from 15,440 unique patients. The rates of CA-MSSA and CA-MRSA isolates per 10,000 patient encounters increased significantly from 10.5 and 3.2 in 2001 to 17.3 and 15.2 in 2008, respectively (both p-value < 0.05). There was no significant trend for HA- MSSA or HA-MRSA over the 8 year period; however over the period 2005-2008 the rate decreased significantly for HA-MRSA from 60.0 to 42.0.
Conclusion: Our study population had continued increases in CA-SA infection rate and recent decreasing rates on HA-MRSA. Our data indicate HA-MRSA incidence rates in our population decreased from a peak in 2005, in the absence of active surveillance for MRSA. This is also consistent with the well described cyclic nature of SA disease.
John Burke, MD, LDS Hospital, Salt Lake CIty, UT, Toru Kamiya, MD, LDS Hospital and Univ. of Utah, Salt Lake City, UT, Rajesh Mehta, RPh, MS, Intermountain Health Care, Salt Lake City, UT, David Pombo, MD, LDS Hospital, Salt Lake City, UT and  D. J. Pombo, None..
R. R. Mehta, None..
T. Kamiya, None..
J. P. Burke, None.