Coagulase negative staphylococci (CONS) are the most common cause of bacteremia in the Neonatal Intensive Care Unit (NICU). It is unclear as to whether simple colonization of infants is the source of these infections, or whether there are other endemic sources. In order to determine their epidemiology, we investigated the clinical and molecular characteristics of CONS. To determine acquisition and transmission in the NICU, 30 episodes of bacteremia in 19 neonates were evaluated over a one year period. Risk factors for infection as determined by multivariate analysis included degree of prematurity, intravenous catheters (especially central intravenous catheters), and prior antibiotics. 14 distinct strains were identified by pulsed field gelεlectrophoresis of chromosomal DNA. One strain was common to four patients,two strains were found in three patients each, and four different strains were shared by two patients each. Common strains were noted almost exclusively in patients with overlapping hospital stays, and persisted less than three months before being replaced by another common strain. These data suggest nosocomial acquisition of CONS strains causing bacteremia, and supports evaluation of potential control methods, including handwashing and aseptic techniques during intravenous catheter insertion. Pulsed field gel electrophoresis is an extremely important tool in determining the epidemiology of infective agents in the NICU setting.
