ISR 63 - Impact of a Targeted Methicillin-resistant Staphylococcus Aureus Decolonization Strategy on Hospital-onset MRSA Infections

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infections are a source of morbidity and mortality for hospitalized patients. While a universal MRSA decolonization approach is considered more effective than active surveillance and decolonization of MRSA-colonized patients in the intensive care unit (ICU) setting, a majority of MRSA bloodstream infections (BSI) at our hospital occur outside the ICU, leading us to develop a targeted decolonization program. The objective of this study was to evaluate the impact of this strategy on hospital-onset (HO) MRSA infections.

Methods: Targeted MRSA decolonization began at our 800-bed tertiary care hospital in quarter 3 of 2017. Infection Preventionists used electronic medical record (EMR) indicators and custom lists to actively identify MRSA-colonized patients and place orders for 2% intranasal mupirocin twice daily for 5 days, through an approved MRSA decolonization protocol. All patients at our hospital also receive daily chlorhexidine gluconate bathing. The primary outcome was HO-MRSA clinical infections defined as positive MRSA clinical culture obtained >= day 4 of hospital admission. The secondary outcome was HO-MRSA BSI defined as a positive MRSA blood culture >= day 4 of admission. We compared quarterly HO-MRSA clinical infection and HO-MRSA BSI incidence per 10,000 patient-days for the pre-intervention (6 years from July 2011-June 2017) and post-intervention (5 years from July 2017-September 2022) periods. The two-tailed Student’s t-test was used to compare the mean quarterly incidence pre- and post-intervention; p < 0.05 was considered significant.

Results: Comparing post- to pre-intervention, the mean quarterly incidence of HO-MRSA clinical infections decreased from 4.3 to 2.7 per 10,000 patient-days (p= < 0.001), and HO-MRSA BSIs declined from 1.4 to 0.7 per 10,000 days (p < 0.001).

Conclusions: An Infection Preventionist-led targeted MRSA decolonization strategy leveraging the EMR to identify patients and place mupirocin orders was successful in significantly reducing hospital-onset MRSA infections including BSI at a large academic medical center.