Control of Methicillin-Resistant Staphylococcus aureus in a Neonatal Intensive Care Unit

Abstract

INTRODUCTION: In September 2001, four infants in the neonatal intensive care unit (NICU) were culture-positive for MRSA (three infections). MRSA was not previously isolated in the NICU, and an epidemiological investigation was undertaken. Initial screening of all 28 infants and 236 healthcare workers (HCWs) demonstrated MRSA colonization of 11 additional infants and 6 HCWs. METHODS: An enhanced infection control program was introduced. This included weekly nasal surveillance cultures of all NICU infants, cohorting and strict contact isolation of MRSA-positive infants, and introduction of an alcohol handwash. MRSA-positive infants were cared for by designated HCWs. All MRSA-positive babies and HCWs were treated with nasal mupirocin for 5 days. HCWs and housekeeping staff underwent intensive reeducation. RESULTS: Over a 12-month period the outbreak involved a total of 38 neonates with MRSA (five bacteremias, two deaths). Pulsed-field gel electrophoresis (PFGE) of all MRSA isolates revealed three MRSA clones (A, B, and G) in neonates and six MRSA clones (A-F) in HCWs. Transmission of the initial MRSA clone A was controlled 3 weeks after starting weekly surveillance. PFGE of subsequent MRSA isolates from 23 neonates was suggestive of repeated reintroduction of different MRSA clones from the adjacent adult hospital, where it is endemic. Further spread of these MRSA clones was controlled within 1–5 weeks. CONCLUSIONS: Eradication of MRSA from the NICU is problematic. This study demonstrates that transmission can be controlled through the combination of enhanced infection control, weekly surveillance cultures, and molecular typing studies.