Survival time of methicillin-resistant Staphylococcus aureus-free status after institutional clearance

To determine the durability of methicillin-resistant Staphylococcus aureus (MRSA)-free status after patients are removed from contact precautions and the association of specific clearance policy variables with survival.

Retrospective cohort study from October 2007 to April 2013.

Veteran Affairs Boston Healthcare System.

Patients with a prior history of MRSA who were removed from contact precautions after deemed cleared of their MRSA status by infection prevention.

Active nasal screening results and clinical data from acute, long-term, and outpatient care facilities were evaluated to determine survival of MRSA-free status in a time-to-event analysis.

A total of 351 unique patients were followed for 107,112 patient-days. The median age was 68 years. Overall, 249 (71%) of patients remained MRSA-free, and 102 (29%) reverted to MRSA positive. The median MRSA-free survival was 880 days. Comorbidities, presence of indwelling devices, and the use of systemic antibiotics at the time of clearance screening were not associated with MRSA-free survival. More than 21,000 days of inpatient isolation days were avoided during the study period.

The majority of patients removed from contact precautions remained MRSA-free for more than 2 years. Antibiotic use at the time of clearance was not associated with reductions in MRSA-free survival. These findings can be used to simplify clearance criteria, promote clearance policies, and reduce patient isolation days.