The nonspecifity of signs for infection in the newborn leads to frequent sepsis workups and the use of antibiotics. The wide range of potential pathogens makes it difficult to differentiate between those infants with true infection and those whose blood culture is contaminated. There are currently no microbiologic techniques or clinical criteria to differentiate true pathogens from contaminates. Skin colonization is common and increases with time in the neonatal intensive care unit but does not predict systemic illness. We reviewed 39 charts of infants with positive blood cultures. Each infant had a paired blood culture in addition to white blood cell count (WBC), leukocyte indices, platelet count and C-reactive protein (CRP). 24 were considered true pathogens; 15 were considered contaminants. Infants with proven sepsis were likely to have abnormal total white count (p value< 0.05) and elevated CRP (p value <0.0001). The odds ratio of not having an infection with a normal WBC and CRP was 1.6. The odds ratio of having a true infection with abnormal WBC and CRP was 1.2. No infant with true infection had a normal screen. Normal serial white counts and CRP make the diagnosis of true infection unlikely. A normal screen is useful in differentiating a contaminant from a true pathogen even in the premature population and will allow antibiotic therapy to be discontinued earlier safely, thereby reducing length of stay.
