Impact of a methicillin-resistant Staphylococcus aureus active surveillance program on contact precaution utilization in a surgical intensive care unit*

Abstract

To determine the impact of an active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) on contact precaution utilization, as measured by additional number of contact precaution days attributable to the active surveillance program. Prospective cohort study. Twenty-four-bed surgical intensive care unit (ICU). All patients admitted to the surgical ICU. Nasal cultures for MRSA were performed at admission to a surgical ICU for 19 months. Patients admitted>48 hrs also received weekly and discharge nasal cultures. Clinical data, including start date and initial indication for contact precautions, were prospectively collected. Of 1,893 admissions, 253 (13%) were found to be MRSA-positive during their ICU stay. One hundred forty-six (58%) were identified by nasal culture alone. Compared with the first 10 months of study, the prevalence of MRSA on admission to the ICU during the last 9 months of the study period significantly increased (7.2% vs. 11.4%, p<.001). Acquisition of MRSA by noncolonized patients remained constant between the first 10 months and last 9 months of study (7.0 vs. 5.5 cases per 1000 patient days, p=.29). Two hundred fourteen (6%) of 3461 total contact precaution days in the ICU were attributable to MRSA active surveillance. In sensitivity analyses, the implementation of rapid, same-day results for MRSA active surveillance would increase contact precaution days by 15% compared with no surveillance. If the total number of vancomycin-resistant enterococci patients in the ICU were reduced by 50%, the contact precaution days attributable to active surveillance would increase to 9%. MRSA active surveillance increased total contact precaution days in this ICU by 6% yet detected 58% of MRSA cases that would have been otherwise missed. Despite an increasing prevalence of MRSA on admission to the ICU, the acquisition rate has remained constant.