Active Surveillance for MRSA in the Emergency Department of a Community Hospital

Background: Methicillin-resistant Staphylococcus aureus (MRSA) colonization can result in MRSA clinical infection. Because hospital-acquired infections (HAIs) caused by MRSA, occasionally resulting in death, had continued to occur at our hospital despite routine infection control practices, we instituted 2 successive systems of active MRSA surveillance.

Objective: To observe the rate of targeted HAIs caused by MRSA, as well as the number of MRSA deaths, before and during active MRSA surveillance.

Methods: During July 2006 through June 2007 (Period 1), our baseline period, only patients previously identified as MRSA or newly diagnosed by positive clinical cultures were put on contact precautions. During July 2007 through  June 2008 (Period 2 ) we also performed nasal swab cultures for MRSA on patients admitted to the Intensive Care Unit (ICU). From July 2008 through June 2009 (Period 3) we performed nasal swabs for MRSA DNA on patients admitted through the Emergency Department (ED) and discontinued ICU screening.  Targeted surveillance for HAIs was done in the following areas: Class I surgery, Colon surgery, C-sections, Hysterectomies, Ventilator-associated pneumonia, Central Venous Catheter-related Blood Stream Infections, and Foley-catheter infections (ICU only). National Healthcare Safety Network (NHSN) definitions were used.  Any patient found to have a positive clinical culture or screening test for MRSA was put in isolation per CDC guidelines. We compared the prevalence rate of targeted hospital-acquired infections (T-HAIs) caused by MRSA (# infections/ 1000 pt days) and the number of deaths caused by MRSA T-HAI, before and during each phase of the active surveillance program.

Results: The prevalence rate of MRSA T-HAI infection dropped from 0.15 to 0.12 to 0.05 over the three periods resulting in a 67% drop from Period 1 to Period 3, while the total T-HAIs prevalence dropped from 1.28 in Period 1 to 0.95 in Period 2 to 0.85 in Period 3 for a 33% rate reduction between Period 1 and Period 3.The percentage of T-HAI's which were caused by MRSA changed from 11.76% in Period 1, to 14.29% during Period 2, to 6.25% during Period 3, resulting in a 46% drop between Periods 1 and 3. In addition, while there was one death annually during 2005, 2006, and 2007 due to a MRSA T-HAI, there have been no MRSA T-HAI deaths since screening began.

Conclusions: Active screening for MRSA in patients admitted through the ED was associated with a drop in the prevalence rate of T-HAI's caused by MRSA, in the total T-HAI rate, and the percentage of T-HAI caused by MRSA. In addition, since screening started, there have been no deaths due to T-HAI MRSA. MRSA active surveillance can be a useful tool to decrease MRSA T-HAI rate and MRSA T-HAI deaths, and may contribute to a decrease in total T-HAI infection prevalence rate at a community hospital.