Coagulase-negative staphylococcal bacteremia in newborns

Coagulase-negative staphylococci (C-NS) recently have been identified as common causes of septicemia in high-risk newborns. In this review of the incidence and clinical significance of C-NS blood culture isolates from infants with suspected septicemia in a newborn intensive care unit (NICU), 2.2 percent of blood cultures in an 18-month period yielded C-NS. Based on the criterion of growth in multiple blood cultures as evidence of bacteremia, six of 30 infants (20%) were bacteremic, 17 (57%) represented probable contaminants (on the basis of growth in only one of two paired blood cultures with CN-S), and seven cases (23%) were indeterminant (only one culture was obtained). In those infants considered bacteremic, onset occurred between 12 and 51 days of age. In those with probable contaminants, all but three occurred in the first week of life. All infants had manifestations of suspected sepsis and survived the clinical episode. These findings indicate that C-NS growth can be due to nosocomial bacteremia but frequently represents blood culture contamination, especially in infants in the first week of life. At least two paired peripheral blood cultures should be obtained in infants with suspected septicemia to differentiate bacteremia from contamination.