The study of clinical value of sTLR2 in identifying the pathogen of bloodstream infections in septic patients

Abstract

Objective To search specific biomarkers of pathogenic bacteria in patients with sepsis so as to guide early using rationally antibiotic treatment. Methods Prospective survey of 147 patients with sepsis in ICU was carried out from Jan 2012 to Mar 2015. When patients blood culture was positive, clinical data including age, gender, vital signs, blood and, urine routine examination, DIC, blood biochemistry, c-reactive protein (CRP), procalcitonin (PCT), microbial detection, etc were recorded. Cultured blood samples were from central venous catheter and peripheral vessel. ELISA method was employed to detect soluble toll-like receptor 2 (sTLR2) and interleukin-8(IL-8), and the Acute Physiology and Chronic Health Evaluation Ⅱ (APACHEⅡ score) was calculated. The chi-square test and analysis of variance were performed where necessary. Receiver operating characteristic (ROC) curves were used to calculate cut-points (CP) and area under the curve (AUC). Results According to the results of blood culture, patients were divided into three groups: GP group [gram-positive bacteria (G+) group]; GN group [gram-negative bacteria (G-) group]; FG group (fungi group). There were no significantly statistical differences in age, APACHEⅡ score, vital signs and markers of inflammation among three groups (P> 0.05). Gram negative pathogenic bacterium was the most common microbe. Compared with GN group, the level of sTLR2 in the GP group was obviously higher ( P= 0.000); but there was no significant difference in sTLR2 level between GP group and FG group (P= 0.187). The amount of (1, 3)-beta glucan in the FG group was significantly higher than that in the GP group (P= 0.000). The sTLR2 level in FG group was obviously higher than that in the GN group (P= 0.000). There were no significantly statistical differences in PCT, CRP and IL-8 among the three groups (P> 0.05). For the diagnosis of gram negative bacteria infection, sTLR2 area under the curve was 0.768, and the sensitivity and specificity were 88.90% and 59.60%, respectively and the best cut-off point was 8.083 pg/mL. Namely, the diagnosis of gram negative bacteria infection was less likely, when level of sTLR2 was higher than 8.083 pg/mL. The markers of PCT, CRP, (1, 3)- beta glucan and IL-8 were less valuable for the diagnosis of Gram negative bacteria infection because the area under the curve was less than 0.5. Conclusions The combination of inflammatory indicators such as sTLR2 and (1, 3) - beta glucan etc, can imply the kind of pathogenic microorganisms partly. Key words: Sepsis; Bloodstream infections; Inflammatory markers; Soluble TOLL like receptor 2; (1, 3)-beta glucan; Calcitonin; C-reactive protein