A study of the role of multiple site blood cultures in the evaluation of neonatal sepsis.

摘要

BACKGROUND: The optimal number of blood cultures needed to document sepsis in an ill neonate has undergone little critical evaluation. Multiple site cultures may improve pathogen detection if intermittent bacteremia occurs, or if a low density of bacteria is present in the blood. We hypothesized, however, that bacterial clearance is slower and bacteremia more continuous in septic neonates, so that a single site blood culture should be sufficient to accurately document true septicemia.Objective:To determine the need for multiple site blood cultures in the evaluation of neonates for sepsis. DESIGN/METHODS: Clinical data were prospectively collected for 216 neonates who had 269 pairs of blood cultures taken from two different peripheral sites for the evaluation of possible sepsis. A minimum of 1 ml of blood was obtained from the two peripheral sites within 15-30 min of each other. Based on prior retrospective data, we determined that 203 infants would need to have two site blood cultures to demonstrate a significant improvement in pathogen detection at an alpha of 0.05 and a beta of 0.20 (80%) power. RESULTS: A total of 186 culture pairs were taken for evaluation of early-onset sepsis in 186 neonates, while 83 pairs were drawn for evaluation of late-onset sepsis in 43 neonates. In all, 21 neonates from the late-onset group were evaluated more than once, and 12 neonates were evaluated for both early- and late-onset sepsis. In all, 20 (9.2%) of 216 neonates had 22 episodes of culture-proven sepsis at a median age of 18 days. All neonates with positive cultures had the same organism with a similar sensitivity pattern obtained from the two different peripheral sites. The other 196 study neonates had negative blood cultures from both sites. The single episode of early-onset sepsis was caused by Listeria monocytogenes, while all remaining episodes were late-onset with the following organisms: Staphylococcus epidermidis (7), methicillin-resistant Staphylococcus aureus (MRSA) (3), combined MRSA and Candida albicans (2), Candida albicans alone (2), late-onset Group B beta-hemolytic Streptococcus (GBS) (2), Klebsiella pneumoniae (2), Enterococcus fecalis (1), Escherichia coli (1), and Serratia marcescens (1). Since no infant grew organisms from only one of the two sites, the data indicate that the diagnosis of sepsis would have been made correctly in all infants with a single site culture. CONCLUSIONS: Two site blood cultures for the initial evaluation of neonatal sepsis do not have a better yield in pathogen detection. Sepsis in neonates can be detected with no loss of accuracy with a single site blood culture with blood volume of>or=1 ml.