Bringing Down the Flag: Streamlining the Growing Population of Patients on Contact Precautions for Methicillin Resistant Staphylococcus Aurues

Objectives. Methicillin-resistant Staphylococcus aureus (MRSA) is a common hospital-acquired infection and emerging community public health threat. The mainstay of prevention in healthcare systems is to identify patients harboring MRSA, then isolating them with contact precautions.  Policies vary as to when a patient’s “flag” for MRSA can be removed, but most often patients remain labelled indefinitely.  While important for infection control, isolation comes with substantial adverse physical and mental consequences to the patient and added cost to the health care system. The purpose of this study was to assess the prevalence of persistent carriage in patients flagged with past MRSA, and to assess a potential streamlined process for flag removal.

Methods. Outpatients with a flag of past MRSA identified through the electronic medical record were invited to participate.  They were screened with nasal, inguinal, and axillary cultures for MRSA, and a nasal swab for MRSA DNA by polymerase chain reaction (PCR).  If all samples were negative, they returned for a second set of samples 1 week later.  Contact precaution flags were removed if all results were negative.

Results. 139 patients completed the study.  72% of study participants tested completely negative and had their flags removed. The negative predictive value of a single initial nasal PCR was 92%.  Patients with a more recent history of MRSA infection, or recent hospitalization were more likely to be persistent carriers. 

Conclusions. The majority of patients labelled as MRSA carriers do not need to be in continued isolation.  A single nasal PCR is a rapid test that reasonably predicts which patients have cleared their colonization and can have their flag removed.  Excluding patients with recent MRSA or hospitalization could improve the negative predictive value even further.