C-reactive protein as biochemical indicator of bacterial infection in neonates.

Serial quantitative measurements of C-reactive protein (CRP) were performed, using an automated enzyme immunoassay method, in 127 neonates (114 premature and 13 full-term) classified in three groups: neonates with a normal postnatal course (group 1, n = 69), neonates with clinical suspicion of bacterial infection but with negative cultures (group 2, n = 49), and neonates with proven bacterial infection (group 3, n = 9). A total of 545 serial serum CRP concentrations were determined. In group 1, CRP concentrations were below the detection limit of the method (10 mg/L) except in one neonate who suffered from neonatal anoxia but whose clinical course was uncomplicated (CRP: 31 mg/L within 24 h of life). Thirty-three neonates of group 2 had CRP values consistently below 10 mg/L while 16 had elevated CRP concentrations at least on one occasion ranging from 10 to 70 mg/L. Diagnoses other than bacterial infection could explain the raised CRP concentrations in neonates of group 2. CRP concentrations were found to be elevated (greater than 80 mg/L) during the course of infectious diseases in all neonates with proven bacterial infection (septicemia (4), pneumonia (1), multiple micro-abscesses (1), urinary tract infection (3]. Serial measurement of CRP concentrations are shown to be valuable in detecting bacterial infection in neonates as well as in following the efficacy of antimicrobial therapy.