MRSA Colonization Among At-Risk Surgical Patients in a Large Community Hospital System

Background: In 2007, HCA implemented an enterprise wide MRSA reduction campaign for inpatients in 154 hospitals across 20 states, which included Active Surveillance Cultures (ASC) for MRSA among at-risk populations.    At-risk populations included surgical patients undergoing total hip and knee joint replacement, open spine and open heart procedures.  Literature suggests that preoperative MRSA screening and decolonization results in decreased infections.  

Objective: Determine the prevalence and distribution of MRSA colonization among at-risk surgical patients.   Validate at-risk surgical populations and develop strategies to improve ASC and preoperative MRSA prophylaxis.  

Methods: Admission or presurgical nursing queries identified patients that met criteria for a nares swab to detect MRSA colonization.    Swabs were obtained either at the presurgical visit or at admission and tested by BD CHROMAgar or GeneOhm PCR methods.   The majority of labs performed agar testing.  Decolonization of MRSA positive patients was left to the discretion of the surgeon.    Selected surgical procedure codes defined major stratified case groupings and results. 

Results: Over 215,000 of eligible surgical patients qualified for ASC from July 2007 thru July 2009.   This was comprised of 17% total hip, 26% total knee, 36% open spine and 20% open heart procedures.   Over 85% were tested for ASC (range 59-94% by geographic regions); 90% were tested within 48h of admission.  ASC testing within each surgical strata also differed by region (range 53-98%).  Of the patients tested, 4.5% were colonized with MRSA (range 2.8 to 5.7%).  MRSA colonization differed among the surgery case strata: 4% total knee, 4% open spine, 4.7% open heart and 6.4% total hip.  Prevalence of MRSA colonization increased both with age and with other factors including prior MRSA history, long term care residence, dialysis and diabetes.   Mean healthcare associated surgical site MRSA infection rates decreased 24% from pre implementation baseline.

Conclusions: Populations within the major surgical strata and geographic regions have differing rates of ASC performed and MRSA colonization.   Based on the initial results, strategies are in development to improve surgeon advocacy of ASC and preoperative prophylaxis among high risk surgical procedures.