Sustained Reduction in the Clinical Incidence of Methicillin-Resistant Staphylococcus aureus Colonization or Infection Associated with a Multifaceted Infection Control Intervention

OBJECTIVE: To assess the impact and sustainability of a multifaceted intervention to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission implemented in 3 chronologically overlapping phases at 1 hospital. DESIGN: Interrupted time-series analyses. SETTING: A Veterans Affairs hospital in the northeastern United States. PATIENTS AND PARTICIPANTS: Individuals admitted to acute care units from October 1, 1999, through September 30, 2008. To calculate the monthly clinical incidence of MRSA colonization or infection, the number of MRSA-positive cultures obtained from a clinical site more than 48 hours after admission among patients with no MRSA-positive clinical cultures during the previous year was divided by patient-days at risk. Secondary outcomes included clinical incidence of methicillin-sensitive S. aureus colonization or infection and incidence of MRSA bloodstream infections. INTERVENTIONS: The intervention--implemented in a surgical ward beginning October 2001, in a surgical intensive care unit beginning October 2003, and in all acute care units beginning July 2005--included systems and behavior change strategies to increase adherence to infection control precautions (eg, hand hygiene and active surveillance culturing for MRSA). RESULTS: Hospital-wide, the clinical incidence of MRSA colonization or infection decreased after initiation of the intervention in 2001, compared with the period before intervention (P = .002), and decreased by 61% (P < .001) in the 7-year postintervention period. In the postintervention period, the hospital-wide incidence of MRSA bloodstream infection decreased by 50% (P = .02), and the proportion of S. aureus isolates that were methicillin resistant decreased by 30% (P < .001). CONCLUSIONS: Sustained decreases in hospital-wide clinical incidence of MRSA colonization or infection, incidence of MRSA bloodstream infection, and proportion of S. aureus isolates resistant to methicillin followed implementation of a multifaceted prevention program at one Veterans Affairs hospital. Findings suggest that interventions designed to prevent transmission can impact endemic antimicrobial resistance problems.