Genetic relatedness of Staphylococcus epidermidis from infected infants and staff in the neonatal intensive care unit

Background: The genetic relatedness of Staphylococcus epidermidis associated with infections in infants and cultured from the hands of nurses was assessed. Methods: From March 2001 to January 2002, infections caused by S epidermidis were prospectively monitored. Participating nurses had hand cultures performed quarterly following hand hygiene. Pulsed-field gel electrophoresis was performed to determine genetic relatedness of strains from infants and nurses. Results: During the study period, S epidermidis caused 42 of 143 (29%) and 26 of 100 (26%) infant infections and was cultured from the clean hands of 51 of 61 (84%) and 53 of 58 (91%) nurses in neonatal intensive care unit (NICU)-1 and NICU-2, respectively. Fifty-eight clones of Sepidermidis were identified among 173 isolates typed: 38 of 173 isolates (22%) were unique clones detected in a single infant (n = 10) or nurse (n = 28); 42 of 173 (24%) isolates were defined as belonging to small cluster clones (n = 15), ie, were detected in 2 to 4 nurses and/or infants; and 93 of 173 (54%) isolates belonged to large cluster clones (n = 4), ie, detected in 7 to 64 nurses and/or infants. Conclusions: These data suggested that most S epidermidis isolates were shared between infants and nurses. Hand hygiene alone is inadequate to prevent S epidermidis infections, and additional strategies are needed to prevent cross transmission in NICU populations.