Investigation of salivary C‑reactive protein and interleukin‑18 for the diagnosis of neonatal sepsis

Neonatal sepsis is a leading cause of death in neonates worldwide. The investigation of biomarkers for the early diagnosis of neonatal sepsis is in progress with controversial outcomes. The current report aims to evaluate the values of salivary C‑reactive protein (CRP) and interleukin‑18 (IL‑18) for the diagnosis of neonatal sepsis.

In this cross‑sectional study, 89 neonates, including 49 neonatal septic case and 40 healthy group admitted at the neonatal intensive care unit, were evaluated. The salivary samples of IL‑18 and CRP were measured before the antibiotic therapy initiation, as soon as blood samplings. Sepsis diagnosis was confirmed by the positive blood culture. The diagnostic values of the biomarkers were determined using the receiver operating characteristic curve (ROC curve) analysis. Besides, the sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) positive likelihood ratio (LR+), negative likelihood ratio (LR‑), and diagnostic accuracy were measured.

Salivary CRP level was remarkably higher in septic case than healthy group (5.2 ± 4.61 vs. 3.5 ± 1.7; P = 0.02), while salivary IL‑18 was not different between the groups (0.1 ± 0.29 vs. 0.04 ± 0.19; P = 0.25). The ROC curve for IL‑18 showed insignificant values (P = 0.37). The ROC curve of salivary CRP showed area under the curve of 0.63 (95% confidence interval: 0.51–0.74; P = 0.03) with the sensitivity, specificity, PPV, NPV, LR+, LR − and diagnostic accuracy of 44.9% (31.8–58.7), 80% (65.2–89.5), 73.3% (55.5–85.82), 54.2% (41.6–66.3), 60.6% (50.29–70.18), 2.24 (1.57–3.2), and 0.68 (0.63–0.75) at the cutoff of 4.55 ng/L, respectively.

Based on the findings of the current study, salivary CRP can be considered a biomarker for the early diagnosis of neonatal sepsis, while no statistical values for salivary IL‑18 were detected. Due to the significance of neonatal sepsis, further evaluations are strongly recommended.