The performance of haematological screening parameters and CRP in early onset neonatal infections

Background: In neonates with early onset sepsis (EOS), the haematological screening parameters and C-reactive protein (CRP) have wide variations in performance. Objective: To evaluate the performance of haematological screening parameters and CRP in blood culture positive neonatal EOS. Methods: We retrospectively studied the neonates who were suspected to have bacterial infections within the first 48 hours of life, based on the risk factors and/or the clinical features in whom haematological screening parameters, CRP and blood cultures were obtained. The screening parameters included total leukocyte count (TLC), the ratio of immature to mature neutrophil count (B: N), micro-ESR, platelet count (PLT), toxic granules (TG) and cytoplasmic vaccuolations (CV) in peripheral smear, and CRP. The screening parameters were assessed for individual performance and in combination in culture positive neonates. Results: Of the 1291 neonates who were screened for EOS, 212 (16.4%) had positive blood cultures. The male to female ratio was 1.08:1. Preterm, small for gestational age and symptomatic newborns constituted 33.9%, 17.9% and 39.2% of the total number of neonates respectively. Coagulase negative Staphylococcus, Klebsiella and Pseudomonas were the predominant culture isolates. Among the haematological parameters, the positivity was best with micro-ESR (44.8%) and the least with TG/CV (2.8%). Any 2 or more parameters were positive in one third of the subjects. TLC and micro-ESR had significantly more positivity among the symptomatic than the asymptomatic neonates (P<0.01). Odds of any 2 or more parameters which were positive for symptomatic relatives to the asymptomatic neonates was 3.89 (95% CI: 2.14 - 7.06; P <0.001) Conclusion: The sensitivities of the traditional haematological screening parameters and CRP were not satisfactory in identifying the neonates with EOS. A relatively better performance is expected in the symptomatic than in the asymptomatic neonates.