Universal MRSA Screening to Assess Colonization Results in Sustainable Eradication of Hospital-Associated MRSA in a Tertiary Care NICU

Background: Outbreaks of MRSA in NICU settings have been reported since the 1990’s.  Rates of invasive MRSA infections in neonates have increased over the past decade and have resulted in significant morbidity and mortality.  Preterm and low birth weight infants colonized with MRSA are at increased risk of invasive MRSA disease and may increase the risk of MRSA transmission. In late 2006/early 2007, the NICU experienced an increase in hospital-associated MRSA colonization and/or infection events.

Objective:  The goal of this project was to determine if routine MRSA screening for all NICU admissions would result in a sustainable decrease in hospital-associated MRSA in NICU patients

Methods: Universal MRSA screening was instituted in February 2007 on all admissions to the NICU with the exception of patients; a) known to be positive for MRSA, b) negative for MRSA on a screen in the prior month, or c) admitted for less than 24 hours.  All patients tested for MRSA were initially placed on contact precautions pending MRSA results.  Initial MRSA lab testing with chromogenic agar provided results within 48 hours.  Real-time PCR testing was initiated in December 2008 with results available within 4-6 hours.  The unit received monthly rates of MRSA screening compliance, hospital-associated MRSA events (colonization and/or infection), and percent of patients that tested positive for MRSA upon admission. Tracheal aspirates were monitored for MRSA colonization or infection. Serial and discharge screening for MRSA was not performed

Results: From August 2006 through January 2007, there were 0.94 MRSA events/1000 patient days.  After universal MRSA screening, the rate of MRSA events significantly decreased to 0.24 MRSA events/1000 patient days (through October 2009).  Compliance with admission screening was >99% and 2% of neonates screened positive for MRSA upon admission.  From 10/07 – 8/09, there were 236 culture positive tracheal aspirates.  Thirty-one (13%) were positive for Staphylococcus aureus of which 4 (13%) were MRSA.  Since April 2008 there have been no new hospital-associated MRSA events.

Conclusions: Hospital-associated MRSA events dramatically decreased in the NICU after the initiation of universal MRSA screening.  Staff remains compliant with performing MRSA screening on new admissions to the unit.  The prevalence of MRSA in neonates admitted to the NICU remains low.  Current rates of hospital-associated MRSA events and rates of MRSA in tracheal aspirates do not support the need for serial or discharge screening for MRSA in the unit.  There have been no new hospital-associated MRSA events in the NICU for over 18 months. This study supports the validity of universal MRSA screening in a low MRSA prevalence NICU and does not support the need for additional serial or discharge screening for MRSA to result in a sustainable decrease in hospital-associated MRSA events.