Epidemiology of Persistent Coagulase Negative Staphylococcal Bacteremia in Newborn Intensive Care Infants.

Abstract

BACKGROUND: Coagulase-negative staphylococcal (CONS) bacteremia is the most common nosocomial infection in most newborn intensive care units (NBICU). Infected infants have increased mortality, and morbidity compared to uninfected peers. At the University of Utah NBICU increasing numbers of infants have developed persistent (cultures positive for >48 hours after initiation of antibiotics to which organisms are susceptible in vitro) and prolonged persistent (positive for > 96 hours) CONS bacteremia.OBJECTIVE: To determine rates of persistent CONS bacteremia in NBICU infants in 2002–2003 and to compare risk factors for prolonged persistent vs. persistent CONS bacteremia.DESIGN/METHODS: A computerized microbiology database identified positive NBICU blood cultures from 1999–2003. Chart review of infants with CONS bacteremia documented possible risk factors for persistent and prolonged persistent infection in 2002–2003. Discrete variables were analyzed by chi-square for trend. Analysis for normally distributed continuous variables was by t-test, for non-normally distributed continuous variables by Mann-Whitney test.RESULTS: From 2001–2003, the frequency of bacteremia due to all bacteria has remained stable (0.03/1000 patient days, p= 0.9). From 1999–2003, CONS bacteremia increased (0.3–0.8–0.7–0.9/1000 admissions, p<0.01). Persistent CONS bacteremia (culture positive for >48 hours despite appropriate antibiotics) also increased (0.0–0.2–0.3–0.4–0.5/1000 admissions, p<0.01). Analysis of 51 infants was performed to determine risk factors for prolonged persistent CONS. Sixteen had CONS infection for 48–96 hours vs. 35 for >96 hours. Significant differences were found in days of antibiotics prior to onset (p=0.03), feeding intolerance at onset (p=0.03), and ventilator days associated with CONS (p<0.001). No difference in gestational age, day of life (DOL) of bacteremia onset, DOL to full enteral feeds, birth weight, or association with central vascular catheter < 72 hours prior to first positive culture was found.CONCLUSIONS: Persistent CONS has increased in our NBICU from 1999–2003. Significant differences were found between bacteremia < or > 96 hours with respect to prior days of antibiotic exposure, feeding intolerance, and CONS associated ventilator days. Differences were not found in gestational age, DOL onset, birth weight, indwelling central line in the 72 hours prior to CONS onset or time to full enteral feeds.