Background Since pathogen detection is often not possible in newborns the diagnosis of early onset sepsis (EOS) is based on clinical examination, blood count and values of C-reactive protein (CRP) or other inflammatory indices. Aim of the study was a critical evaluation of CRP as a diagnostic marker in the detection of EOS.

Methods Data of all newborns hospitalized during the last 4 years (2004–2007) at the NICU of the Paediatric Department of the Medical University Graz and having CRP values done within the first 72 hours of life was analysed retrospectively. EOS was defined as clinical signs of sepsis with positive risk factors or laboratory tests.

Results 126 of 690 neonates had diagnosis of EOS, 12 of them were culture positive. 162 neonates had levels of CRP above 8 mg/L. In culture positive EOS all 12 newborns (100%) had elevated levels of CRP compared to 58/114 newborns (51%) with culture negative EOS. 72/564 newborns (13%) had elevated CRP levels without clinical EOS. Elevated values were also found in 20/36 newborns (56%) with unclear infectious status. Sensitivity (56%) and positive predictive value (43%) for CRP were low compared to specificity (81%) and negative predictive value (86%). Additionally, mean CRP (±SD) were lower in preterm infants (5.8±10.2 mg/L) compared to term infants (13.0±23.6 mg/L).

Conclusion Serial determination of CRP values in the diagnosis of EOS still seems to be useful, but a lot of cofactors cause non inflammatory elevations of CRP. Preterm infants have lower CRP values compared to term infants.