Emergence of Resistant Staphylococci on the Hands of New Graduate Nurses

BACKGROUND: The aerobic microbial hand flora of experienced and new graduate nurses were followed over time to examine the relationship between duration of employment in an intensive care setting and the types, quantities, and resistance patterns of microbial hand flora. METHODS: In a 23-month prospective study on a level-III/IV neonatal intensive care unit (NICU), hand flora of nine new graduate nurses was compared with the flora of 12 experienced nurses on the same unit. An “experienced nurse” was a nurse with >10 years of full-time nursing experience on the specific NICU. A “new graduate nurse” was a recent nursing school graduate with <2 months full-time nursing experience on the specific NICU. Cultures were obtained at baseline and quarterly from each experienced and new graduate nurse. Baseline and final cultures of S. epidermidis were further examined using pulsed-field gel electrophoresis. RESULTS: One hundred fifty hand cultures were obtained, with 237 isolates recovered. At baseline, a significantly larger proportion of experienced nurses had methicillin-resistant staphylococci isolated from their hands when compared to the new graduate nurses (p=0.003). In a second culture obtained 1–4 months later, there were no longer significant differences between the proportions of nurses with methicillin-resistant staphylococci (p=0.13). By the last culture, all staphylococcal isolates were methicillin-resistant in both nurse groups (p=1.0); three were methicillin-resistant S. aureus. CONCLUSION: Colonization with methicillin-resistant staphylococci occurred after brief exposure to the hospital environment. Furthermore, at final culture both groups shared a dominant hospital-acquired strain of S. epidermidis.