Evaluation of serum and salivary C-reactive protein for diagnosis of late-onset neonatal sepsis: A single center cross-sectional study

Abstract Objective: To evaluate the diagnostic utility of salivary C-reactive protein (CRP) and its potential correlation with serum CRP levels in full-term neonates with late-onset sepsis (LOS). Methods: This cross-sectional study included 90 neonates assigned to three equal groups: culture proven LOS, clinical LOS and a control group. Clinical findings and routine laboratory data including complete blood pictures and blood culture results were documented. Highly sensitive serum CRP was measured according to hospital protocol, while salivary CRP levels were measured using enzyme-linked immunosorbent assay. Results: The median serum CRP was significantly higher in septic neonates compared to controls (p < 0.001). For serum CRP, the optimum cut-off value for LOS diagnosis was found to be 7.2 mg/L with sensitivity, specificity, positive and negative predictive values of 91, 100, 100, and 85.7%, respectively. No significant difference was observed in levels of salivary CRP among the 3 study groups (p = 0.39). No correlation was found between the levels of salivary and serum CRP (r = 0.074, p = 0.49). Conclusion: Serum CRP, at a cut-off value of 7.2 mg/L, exhibited a high specificity and positive predictive value in LOS diagnosis, whereas salivary CRP levels weren't significantly different between the 3 study groups nor did they predict abnormal serum CRP thresholds in newborns with sepsis.

Salivary C-reactive protein, mean platelet volume and neutrophil lymphocyte ratio as diagnostic markers for neonatal sepsis / Proteína C reativa salivar, volume médio de plaquetas e proporção de neutrófilos/linfócitos como marcadores de diagnóstico de sepse neonatal

Abstract Objective: To assess the applicability of salivary C-reactive protein, mean platelet volume, neutrophil-lymphocyte ratio, and platelet lymphocyte ratio in the diagnosis of neonatal sepsis. Methods: Prospective case-control study of 70 full-term neonates, 35 with sepsis (20 with proven sepsis and 15 with clinical sepsis) and 35 healthy controls. Serum and salivary C-reactive protein concentrations were measured by enzyme-linked immunosorbent assay while mean platelet volume, neutrophil-lymphocyte ratio, and platelet lymphocyte ratio were measured by automated blood cell counter. Results: This study showed statistically significant difference of mean salivary C-reactive protein between septic neonates and controls (12.0 ± 4.6 ng/L vs. 2.8 ± 1.2 ng/L) respectively. At a cut-off point of 3.48 ng/L, salivary C-reactive protein showed 94.3% sensitivity and 80% specificity. Salivary C-reactive protein also showed good predictive accuracy for predicting elevated serum C-reactive protein values in septic neonates. Mean platelet volume and neutrophil-lymphocyte ratio showed significant difference between septic neonates and controls (10.2 ± 1.2 fL vs.8.0 ± 0.5 fL; 2.9 ± 1.7 vs. 1.6 ± 0.4, respectively). At a cut-off point of 10.2 fL, mean platelet volume presented 80% sensitivity and specificity. At a cut-off point of 2.7, neutrophil-lymphocyte ratio presented 80% sensitivity and 57.1% specificity. Conclusion: This study provides support for further studies on the usefulness of salivary C-reactive protein, mean platelet volume, and neutrophil-lymphocyte ratio as diagnostic markers for neonatal sepsis.

Resumo Objetivo: Avaliar a aplicabilidade da proteína C reativa salivar, do volume médio de plaquetas, a proporção de neutrófilos-linfócitos e a proporção de plaquetas/linfócitos no diagnóstico de sepse neonatal. Métodos: Estudo caso-controle prospectivo de 70 neonatos a termo, 35 com sepse (20 com sepse comprovada e 15 com sepse clínica) e 35 controles saudáveis. As concentrações de PCR no soro e salivar foram medidas por ensaio imunossorvente ligado a enzima (Elisa), ao passo que o VMP, PNL e PPL foram medidos por contador de células sanguíneas automatizado. Resultados: Este estudo mostrou uma diferença estatisticamente significativa da média de PCR salivar entre os neonatos com sepse e os controles (12,0 ± 4,6 ng/L em comparação com 2,8 ± 1,2 ng/L), respectivamente. Um ponto de corte 3,48 ng/L na PCR salivar mostrou sensibilidade de 94,3% e especificidade de 80%. A PCR salivar mostrou, ainda, boa precisão preditiva para prever altos valores de PCR no soro em neonatos com sepse. O VMP e a PNL mostraram diferença significativa entre os neonatos com sepse e os controles (10,2 ± 1,2 fL em comparação com 8,0 ± 0,5 fL), (2,9 ± 1,7 em comparação com 1,6 ± 0,4), respectivamente. O VMP no ponto de corte 10,2 fL apresentou 80% de sensibilidade e especificidade. A PNL no ponto de corte 2,7 fL apresentou 80% de sensibilidade e 57,1% de especificidade. Conclusão: Este estudo fornece uma base para outros estudos na utilidade da PCR salivar, VMP e PNL como marcadores de diagnóstico de sepse neonatal.