The changing susceptibilities of methicillin-resistant Staphylococcus aureus at a midwestern hospital: The emergence of “community-associated” MRSA
published online 05 January 2009.
Background
The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has been well described; however, few studies have reviewed long-term hospital-wide data.
Methods
This retrospective study of adult patients used the first culture per patient per visit positive for MRSA for 1996 to 2005. Isolates were categorized as community-associated or health care–associated phenotype based on antibiotic susceptibilities. χ2 tests for trend and linear regression analyses were performed.
Results
The annual prevalence of CA-MRSA increased significantly over the 10-year study period (from 43 of 507 [8.9%] MRSA cultures in 1996 to 672 of 1697 [39.6%] MRSA cultures in 2005; P < .01). The proportion of MRSA cultures obtained within 48 hours of hospital admission increased from 50.5% to 79.5% (P < .01). The median age of patients with MRSA decreased, from 60 to 49 years (P < .01). Among the CA-MRSA cases, the proportion of non-Caucasian patients increased from 30.2% to 60.4% (P < .01) and the proportion of patients categorized as low socioeconomic status increased from 25.6% to 35.6% (P < .01). Significant consistent trends were not observed for patient sex or body sites of the cultures.
Conclusion
An increasing number of MRSA with a community-associated phenotype occurred during the 10-year study period. Patterns of decreasing age, increasing non-Caucasian races, and decreasing socioeconomic status were observed among patients with MRSA.
aHospital Infection and Epidemiology Department, Barnes Jewish Hospital, St. Louis, MO
bDepartment of Infectious Diseases, Washington University School of Medicine, St. Louis, MO
Address correspondence to Kathleen M. McMullen, MPH, Mailstop 90-75-500, 4905 Forest Park Avenue, St. Louis, MO 63108.
ABSTRACT