Changing epidemiology of methicillin-resistant Staphylococcus aureus in the Veterans Affairs Healthcare System, 2002–2009

Purpose The epidemiology of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) is changing. Temporal trends and differences between healthcare settings must be described in order to better predict future risk factors associated with this dangerous bacterial infection. Methods A national MRSA-infected cohort was identified from 2002 to 2009 in the Veterans Affairs Healthcare System of the United States: hospital (HOS), long-term care (LTC), and outpatient (OPT). We analyzed within-setting time trends using generalized linear mixed models and between-setting differences with χ 2 and Wilcoxon rank-sum tests. Results The incidence of S. aureus , methicillin-susceptible S. aureus (MSSA), and MRSA infections increased significantly over time in all three settings based on modeled annual percentage changes ( P