Validity of hematologic parameters in identification of early and late onset neonatal infection.

This study was designed to evaluate the utility of hematological parameters and C-reactive protein (CRP) to formulate a sepsis screen to detect sepsis in early and late onset infection. Hundred and fifty neonates clinically suspected of bacterial infection, based on risk factors and/or clinical features were selected for the study. Blood was collected by venipuncture at the time of admission in all neonates. A total leukocyte count (TLC), differential leukocyte count (DLC), its derivatives [Total neutrophil count (TNC or T), ratio of immature to total neutrophil count (I/T), ratio of immature to mature neutrophil count (I/M)] and CRP were obtained. TLC = 10x10(9)/L, TNC = 8x10(9)/L, I/T = 0.16, I/M = 0.25 and CRP = 0.6 mg/dl were found to be good parameters in detection of sepsis. During the first three days of life leukopenia, neutropenia, elevated I/T ratio, elevated I/M ratio and CRP were good diagnostic aids while after 3 days of life CRP was the best single test. This emphasizes use of multiple indicators for detection of sepsis. Using these parameters a sepsis screen was formulated which detected >90% of proven early and late onset sepsis suggesting that other neonates with positive sepsis screen but blood culture negativity may have been truly infected.