Seven-year experience with a surveillance program to reduce methicillin-resistant Staphylococcus aureus colonization in a neonatal intensive care unit.
OBJECTIVE
The objectives of this study were to determine the incidence rates of neonatal methicillin-resistant Staphylococcus aureus colonization and infection after the implementation of a NICU methicillin-resistant S aureus surveillance and isolation program and to describe the characteristics of infants with methicillin-resistant S aureus colonization and invasive disease.


METHODS
From August 2000 through August 2007, all infants admitted to the study NICU were screened for methicillin-resistant S aureus colonization with weekly nasal/rectal swabs; colonized or infected infants were isolated and cared for as a cohort. The annual incidence rates of methicillin-resistant S aureus colonization and infection were monitored, and characteristics of methicillin-resistant S aureus-colonized and -infected infants were compared. Data were collected from infant, maternal, and hospital laboratory records.


RESULTS
During the study period, 7997 infants were admitted to the NICU and 102 methicillin-resistant S aureus-colonized or -infected infants (1.3%) were identified. The incidence of methicillin-resistant S aureus decreased progressively from 1.79 cases per 1000 patient-days in 2000 to 0.15 cases per 1000 patient-days in 2005, but the incidence then increased to 1.26 cases per 1000 patient-days in 2007. Fifteen of the 102 case infants (14.7%) had invasive infections; no significant differences between infected and colonized infants were identified. Methicillin-resistant S aureus isolates with 14 different antibiograms were found during the study period. There was a shift from isolates predominantly likely to be hospital-associated in 2000-2004 to those likely to be community-associated in 2006-2007.


CONCLUSIONS
A continuous program of weekly methicillin-resistant S aureus surveillance cultures and isolation of affected infants was associated with a variable incidence of methicillin-resistant S aureus colonization over a 7-year study period. Methicillin-resistant S aureus was not eradicated from this tertiary-care NICU, and our data suggest that infants were colonized by multiple different methicillin-resistant S aureus strains during the study period.
Gregory
Mary Lucia
ML
Department of Neonatology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Rose Building, Room 318, Boston, MA 02215, USA. mgregory@bidmc.harvard.edu
Eichenwald
Eric C
EC
Puopolo
Karen M
KM
D001900:Boston / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D006786:Hospitals, Urban; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D010356:Patient Isolation; D011159:Population Surveillance; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000517:prevention & control*