P3.J198: Serum C-reactive protein in neonates at 24 hours of life and its association to histopathologic chorioamnionitis and neonatal early-onset sepsis

Background: Histopathologic chorioamnionitis (HCA) is the inflammation of any combination of the amniotic fluid, placenta, fetus, fetal membranes, or decidua. HCA is associated with neonatal early onset sepsis (EOS). The Kaiser Sepsis Calculator (KSC) score is an instrument that predicts neonatal EOS in late preterm and term infants, which is associated with significant neonatal morbidity and mortality. Often, C-reactive protein (CRP) level at 24 hours of life is utilized to determine the need to extend antibiotic administration beyond 48 hours for suspected EOS in infants, even if the blood culture is negative. This leads to an increased duration of use of antibiotics and neonatal hospital stay. In this study, we sought to explore the relationship between a positive CRP level (> 1 mmol/Liter) in infants >= 34 weeks with KSC and histopathologic chorioamnionitis.

Methods: A retrospective cohort study approved by the Institutional Review Board evaluated charts of infants born at two large urban hospitals. The study included infants born from 2014 to 2019 by convenience sampling with a gestational age of 34 weeks or more and a maternal clinical diagnosis of chorioamnionitis, with a CRP performed at around 24 hours after birth to determine the need to continue antibiotics. The population was divided into two groups – CRP positive and CRP negative and compared using the chi-square test for categorical variables and the Wilcoxon rank sum test for continuous variables.

Results: Of the 151 cases that met the inclusion criteria, CRP was positive in 57 cases and negative in 94. Of all the cases, 96.7% received antibiotics, while 82.8% were admitted to the Neonatal Intensive Care Unit. The median gestational age was 39 weeks, and the birth weight was 3.38 Kg. None of the blood cultures were positive in either group. The rate of NICU admission (76.6 vs. 93, p=0.007) and length of stay (3 vs. 6, p=0.001) was significantly longer in the CRP-positive group. There was no association between CRP positivity rate and KSC score (p=0.18), although there was a strong association between CRP positivity and HCA (p < 0.001, Odds ratio 2.6, 95% confidence interval - 1.1 to 5.9). There was no association between KSC score and HCA (p=0.076).

Conclusion: A positive serum CRP level was associated with more antibiotic use, NICU admissions, and a longer length of stay without any positive blood culture. However, a positive CRP value was not associated with a significantly increased EOS risk score but with a diagnosis of histopathologic chorioamnionitis. Providers should be judicious in considering a positive CRP value alone in deciding the duration of antibiotic therapy, as it may reflect placental inflammation rather than an increase in the probability of Neonatal early-onset sepsis.