Exploring the clinical value of procalcitonin, c-reactive protein, white blood cell count, and neutrophil-to-lymphocyte ratio in the early diagnosis of bloodstream infections in children.

Backgroud: In the diagnosis of bloodstream infections (BSI) in children, compared to the gold standard of blood culture, markers in the blood offer advantages such as rapid results and cost-effectiveness. Therefore, we investigated the clinical value of procalcitonin (PCT), C-reactive protein (CRP), white blood cell count (WBC), and neutrophil-to-lymphocyte ratio (NLR) in the early diagnosis of BSI in children.

Methods: This study included a retrospective analysis of 309 suspected BSI cases and patients were categorized into 2 groups based on blood culture results: blood culture-positive group, and blood culture-negative group. The blood culture-positive group was further partitioned into 3 sub-groups based on the type of pathogen: Gram-positive (G +) bacteria, Gram-negative (G-) bacteria, and fungi. Changes in PCT, CRP, WBC, and NLR were evaluated, and pathogen infections among these aforementioned groups were further determined. Moreover, the study employed the receiver operating characteristic (ROC) curve to evaluate the diagnostic value of these indicators in identifying BSI in pediatric patients at an early stage.

Results: Among the 98 strains of pathogens detected in blood culture, 58 (58.2%) strains were G- bacteria, 33 (33.7%) strains were G + bacteria, and 7 (7.1%) strains were fungi. The levels of PCT, CRP, WBC, and NLR were found to be significantly higher in the blood culture-positive group than the blood culture-negative group (p < 0.01). Upon comparing the levels of PCT and CRP in the three pathogen infections, it was found that the fungi group exhibited higher levels than the G- and G + bacteria groups (p < 0.01). The G- bacteria group exhibited higher levels of PCT, CRP, and WBC than the blood culture-negative group (p < 0.05). Similarly, the G + bacteria group exhibited higher levels of PCT, WBC, and NLR than the blood culture-negative group (p < 0.01). Besides, PCT presented the highest diagnostic efficiency among the single-item detections, with an AUC of 0.862 (95% CI: 0.819-0.906). The simultaneous detection of multiple parameters does not necessarily improve diagnostic performance but can enhance detection sensitivity.

Conclusions: PCT and CRP can provide important complementary information for the etiological diagnosis of BSI in children. Elevated levels of PCT and CRP were often associated with fungal or G- bacterial infections, with PCT showing particularly significant effects. Combined use of serum PCT, CRP, WBC, and NLR testing can improve the diagnostic sensitivity of pediatric BSI, reducing the risk of missed diagnoses, thereby enhancing the early diagnostic value of pediatric BSI.