To describe the prevalence of Staphylococcus warneri on the hands of nurses and the clinical relevance of this organism among neonates in the neonatal intensive care unit (NICU).

Prospective cohort study that examined the microbial flora on the hands of nurses and clinical isolates recovered from neonates during a 23-month period (March 1, 2001, through January 31, 2003).

Two high-risk NICUs in New York City.

All neonates hospitalized in the NICUs for more than 24 hours and all full-time nurses from the same NICUs who volunteered to participate.

At baseline and then every 3 months, samples for culture were obtained from each nurse's cleaned dominant hand. Pulsed-field electrophoresis compared S. warneri isolates from neonates and staff.

Samples for culture (n = 834) were obtained from the hands of 119 nurses; 520 (44%) of the 1,195 isolates of coagulase-negative staphylococci recovered were identified as S. warneri. Of the 647 clinically relevant isolates recovered from neonates, 17 (8%) of the 202 isolates that were identified to species level were S. warneri. Pulsed-field electrophoresis revealed a common strain of S. warneri that was shared among the nurses and neonates. Furthermore, 117 (23%) of 520 S. warneri isolates from nurses' hands had minimum inhibitory concentrations for vancomycin of 4 μg/mL, which indicate decreasing susceptibility.

Our findings that S. warneri can be pathogenic in neonates, is a predominant species of coagulase-negative staphylococci cultured from the hands of nurses, and has decreased vancomycin susceptibility underscore the importance of continued surveillance for vancomycin resistance and pathogenicity in pediatric care settings.

To describe the aerobic microbial flora on the hands of experienced and new graduate nurses over time.

A prospective cohort design that examined the relationship between duration of employment in an intensive care unit (ICU) and the microbial flora on the hands of experienced and new graduate nurses during a 23-month period.

A 50-bed, level III-IV neonatal ICU in New York City.

Twelve experienced nurses and 9 new graduate nurses working full time in the NICU.

One hundred fifty samples were obtained from the clean, dominant hands of the nurses. Cultures were performed at baseline and then quarterly for each experienced and new graduate nurse. Baseline and final cultures of Staphylococcus epidermidis were further examined using pulsed-field gel electrophoresis.

At baseline, a significantly larger proportion of the experienced nurses had methicillin-resistant, coagulase-negative staphylococci isolated from their hands compared with the new graduate nurses (95% and 33%, respectively; P = .0004). For a second culture, performed 1 to 4 months later, there were no longer significant differences between the two groups (82% and 54%, respectively; P = .12). By the last culture, all staphylococcal isolates were methicillin resistant in both groups of nurses; 3 were methicillin-resistant S. aureus.

Colonization with methicillin-resistant staphylococci occurred after brief exposure to the hospital environment, despite the use of antiseptic hand hygiene agents. Furthermore, at final culture, the two groups shared one dominant hospital-acquired strain of S. epidermidis.

To determine the costs of the interventions aimed at controlling the 4-month outbreak and to determine the attributable length of stay (LOS) associated with infection and colonization with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae.

A retrospective cost analysis was conducted from the hospital perspective. A micro-costing approach was employed. The LOS of four groups of hospitalized patients were compared with each other. National Perinatal Information Center criteria were used to stratify infants for severity of risk. The LOS of each group was compared with that of a national sample of similarly stratified infants.

A level III-IV, 45-bed neonatal intensive care unit.

Infant groups were infected (n = 8), colonized (n = 14), concurrent cohort (n = 54), and prior cohort (n = 486).

The cost of the outbreak totaled $341,751. The largest proportion of costs was related to healthcare worker time providing direct patient care (2,489 hours at a cost of $146,331). Infected and colonized neonates had longer LOS than either the concurrent cohort or the prior cohort (P < .001). Compared with the national sample, infected infants had a 48.5-day longer mean LOS (95% confidence interval [CI95], 1.7 to 95.2), whereas the prior cohort's mean LOS was 6 days shorter (CI95, -9.4 to -2.9).

This study increases the understanding of the burden of these multidrug-resistant organisms. Further research is needed to estimate the societal costs of these infections and the cost-effectiveness of preventive interventions.