Outbreak of invasive disease caused by methicillin-resistant Staphylococcus aureus in neonates and prevalence in the neonatal intensive care unit.

OBJECTIVES: To describe an outbreak of severe invasive disease caused by methicillin-resistant Staphylococcus aureus (MRSA) and the epidemiology of MRSA in a neonatal intensive care unit during a 12-yr period from 1989 to 2001.
SETTING: A 40-bed, level III neonatal intensive care unit at a children's hospital that admits approximately 450 neonates each year from about 35 neighboring hospitals. PATIENTS: All neonates infected or colonized with MRSA during the outbreak are described. All cases of MRSA infection or colonization in the neonatal intensive care unit from 1989 to 2001 were identified from the database maintained by the hospital epidemiology program.
RESULTS: During the outbreak, 12 neonates were infected or colonized with MRSA, 11 of whom had the epidemic strain. Seven of these 11 neonates had invasive disease, including bacteremia, meningitis, or urinary tract infection, and four neonates were colonized with the epidemic strain. This outbreak was difficult to control by routine epidemiologic measures, and additional control measures, including closing the neonatal intensive care unit to new admissions and treating all infants with intranasal mupirocin, were implemented. Since the outbreak, the prevalence of MRSA in the neonatal intensive care unit has remained low.
CONCLUSIONS: MRSA outbreaks in neonatal intensive care units can be prolonged. Aggressive infection-control measures are often necessary to terminate these outbreaks. Such efforts are essential because MRSA infections in premature neonates can cause significant morbidity and mortality.