Screening and Serial Neutrophil Counts Do Not Contribute to the Recognition or Diagnosis of Late-Onset Neonatal Sepsis

Objective: To determine the validity of screening and serial neutrophil counts in predicting the absence/presence of late-onset sepsis (LOS) in infants with central venous catheters. Study design: Retrospective study of infants admitted to the neonatal intensive care unit (2009-2013) at Parkland Hospital with a central venous catheter and ≥1 LOS evaluations. Infants were categorized as proven or suspect LOS or uninfected based on results of blood cultures, clinical illness, and duration of antibiotics. Receiver operating curves (ROCs) were constructed to predict the absence or presence of LOS using Manroe reference ranges for total and immature neutrophils and the immature to total neutrophil ratio at 0, 12, and 24 hours after blood culture and the neutrophil value score, which assesses serial values. Results: Of the 497 infants with a central venous catheter, 179 underwent ≥1 LOS evaluations, and 140 of 179 (78%) had ≥1 complete evaluations (2 blood cultures and neutrophil values at 0, 12, and 24 hours), resulting in 188 complete LOS evaluations. The gestational age was 28 ± 4 weeks and LOS evaluation occurred at 29 ± 34 days (SD; 4-197 days). Sixty-one (35%) infants had proven LOS, 48 (23%) were suspect, and 71 (38%) were noninfected. ROC comparing proven vs noninfected was ≤0.56 for total neutrophils, immature neutrophils, and immature to total neutrophil ratio at 0, 12, and 24 hours and similar for proven + suspect vs noninfected. ROC for neutrophil value scores and absence of LOS was 0.56. Conclusions: Screening neutrophil values are poor predictors of LOS in neonates with a central venous catheter, as are serial neutrophils and the neutrophil value score. Alternative biomarkers are needed.