Salivary C-reactive protein and mean platelet volume in diagnosis of late-onset neonatal pneumonia

Background: Neonatal pneumonia is an important and major cause of neonatal morbidity and mortality worldwide therefore; its early detection plays a crucial role in successful therapy. Analysis of saliva as a non-invasive method for detection of neonatal diseases holds great promise for improving health care. Till now, salivary C-reactive protein (CRP), mean platelet volume (MPV), neutrophil/lymphocyte ratio (NLR) and platelets/lymphocytes ratio (PLR) have not been studied as markers of diagnosis in neonatal pneumonia. Objective: To assess the applicability of salivary CRP, MPV, NLR and PLR as diagnostic markers in late-onset neonatal pneumonia. Methods: A prospective case control study of 70 full-term neonates, 35 with late-onset neonatal pneumonia and 35 healthy controls, was enrolled. Serum and salivary CRP concentrations were measured by ELISA, while MPV, NLR and PLR were measured by automated blood cell counter. Results: This study showed a statistically significant difference between salivary CRP means in neonates with late-onset neonatal pneumonia vs control neonates (6.2 ± 4.6 and 2.8 ± 1.9 ng/L) respectively. At the cutoff point of 3.8 ng/L, salivary CRP showed 91.4% sensitivity and 80.9% specificity. Salivary CRP also showed accuracy in predicting elevated serum CRP in neonates with pneumonia. MPV showed a significant difference between pneumonia and controls (mean = 10.2 ± 0.7, 8 ± 0.5) respectively. At cutoff point 9.0, it has 80% sensitivity and specificity. Conclusions: The present study showed for the first time that both salivary CRP and MPV are suitable as diagnostic markers in late-onset neonatal pneumonia.