Abstract: Objective To explore the diagnostic value of five infection markers in bloodstream infection. Methods Randomly selected 110 bloodstream infection patients with positive blood cultures and 30 bacterial infection patients with negative blood cultures. Blood were drawn simultaneously with blood cultures; the complete blood count and C-reactive protein (CRP) levels were measured. The white blood cell count(WBC), neutrophil count (NEU), lymphocyte count (LMY), CRP level and neutrophil-lymphocyte count ratio (NLCR) were compared between the two groups. Results The levels of WBC, NEU, NLCR and CRP in bloodstream infection group were significantly higher than those in control group (P <0.05), while LYM was significantly lower than that in control group (P <0.05).Among these five infection markers, the area under the receiver operating characteristic curve (ROC-AUC) was the highest for NLCR (0.808) and LMY (0.756); when the cutoff value for NLCR was >9.33, sensitivity was 63.6%, specificity was 93.3%; and the cutoff value for LYM was ≤0.97, sensitivity was 58.2%, specificity was 86.7%. Furthermore, the NLCR of patients with gram-negative bloodstream infection was higher than those in patients with gram-positive bloodstream infection. NLCR showed important clinical significance in distinguishing strains of different bloodstream infections. Conclusion NLCR is the better predictors than routine parameters in diagnosing bloodstream infection.

Key words: neutrophil-lymphocyte count ratio, bloodstream infection