Prospective surveillance of vancomycin-resistant enterococci in a neonatal intensive care unit

A point-prevalence study of vancomycin-resistant enterococci colonization of the gastrointestinal tract in an Israeli hospital revealed that 14.7% of the 320 inpatients were colonized. Vancomycin-resistant enterococci colonization was detected in most departments except the neonatal intensive care unit. Hence, a prospective longitudinal study of the prevalence of vancomycin-resistant enterococci colonization in the neonatal intensive care unit was conducted. A rectal swab was obtained from every newborn on admission to the neonatal intensive care unit and once weekly thereafter until the patient was discharged. Enterococci were isolated and tested for susceptibility to vancomycin. A total of 84 neonates were enrolled and monitored on average for 3 weeks (SD +/- 3.9, range 1-20 weeks). Mean gestational age was 35.7 weeks (SD +/- 3.9, range 25-42 weeks), and mean birth weight was 2.4 kg (SD +/- 0.9, range 0.45-4.1 kg). Most patients had one or more of the known risk factors associated with colonization with vancomycin-resistant enterococci. Eighty percent of the patients received antibiotics during the study, and 14.3% received vancomycin. The median duration of vancomycin treatment was 12.5 days (SD +/- 16.8, range 5-55 days). Fifty-one of 84 (61%) patients acquired enterococci sensitive to vancomycin during the study period, but no newborn had vancomycin-resistant enterococci. Possible explanations for this finding may be physical isolation of the neonatal intensive care unit from the rest of the hospital, intrinsic differences in the bowel milieu of this age group and the lack of exposure to food and other environmental sources of vancomycin-resistant enterococci from the community.