Background
Despite the recent advances in methods for culturing bacteria, at least 24 hours are needed for most pathogens to be recognized. This period may be critical for the differentiation of a true bacteremia from a contaminated culture. We studied the value of CRP compared to total leukocytes (WBC) and absolute neutrophil count (ANC) in differentiating positive, contaminated and negative blood cultures in various pediatric infectious diseases (pneumonia, acute gastroenteritis (AGE), urinary tract infection (UTI) and acute otitis media (AOM)).
Material and Method
Data was collected retrospectively from patients who were admitted or discharged from to the pediatric ward with one of the above diagnoses. Children with chronic diseases or with immunodeficiency were excluded from the study.
Results
CRP levels were significantly higher in the positive culture group versus contaminated and negative groups (101 mg/L, 30.9 mg/L, 34.3 mg/L, respectively). The total leukocytes and ANC were not of value. When divided into diagnostic subgroups, CRP levels were significantly higher in the positive blood culture groups in patients with pneumonia and AGE. The sensitivity of a CRP value above 85 mg/L for pneumonia and UTI and above 30 mg/L for AGE and AOM in discriminating true positive versus contaminated culture was 70% with a specificity of 67.6% and a positive predictive value of 60.3%.
Conclusions
CRP may be used for differentiation between positive and contaminated blood cultures in children and have been shown to be a better predictor than WBC or ANC for this purpose.

Keywords: Sensitivity and Specificity, Pneumonia - blood, Urinary Tract Infections - blood, Otitis Media - blood, Neutrophils - cytology, Leukocyte Count, Infant, Newborn, Gastroenteritis - blood, Child, Preschool, Child, C-Reactive Protein - physiology, Bacteremia - diagnosis, Adolescent