Background: Neonatal pneumonia (NP) is one of the major causes of neonatal death. Current NP diagnosis depends on a detailed history, physical examination, and radiographic and laboratory findings. There is no specific biomarker or diagnostic indicator of NP.
Methods: In this study, we tried to find a reliable biomarker for quick NP diagnosis by collecting peripheral blood from neonates with NP and transient tachypnea of the newborn (TTN), and subsequently tested the expression of CD64 on white blood cells using flow cytometry. The cellularity of each blood cell population was also quantified. Furthermore, procalcitonin (PCT) and C-reactive protein (CRP) levels were evaluated in the blood sera.
Results: We found that NP patients had moderately increased polymorphonuclear cells (PMNs), as well as elevated PCT and CRP levels in the blood sera. Importantly, the expression of CD64 on PMNs was profoundly increased in NP patients but not TTN patients. The receiver operating characteristic (ROC) curve of PMN CD64 index suggests that PMN CD64 index is sensitive and specific for NP diagnosis.
Conclusions: Our study reveals that PMN CD64 could be a fast and reliable biomarker for NP diagnosis.