血清PCT，IL-6，SAA，hs-CRP水平联合检测对快速筛查早期血流感染的价值

目的　探讨血清降钙素原（PCT）、 白细胞介素-6（IL-6）、血清淀粉样蛋白A（SAA）及超敏-C反应蛋白（hs-CRP）在快速鉴别早期血流感染中的应用价值。 方法 选取2018年3月～2020年8月血培养阳性患者119例,其中革兰阳性菌感染45例，革兰阴性菌感染72例，选取同时期44例健康体检者作为对照组。收集患者血培养当天的血清标本-80℃冻存备用，检测血清中PCT, IL-6 ,SAA及 hs-CRP水平。用统计分析比较血培养阳性组及健康体检组中四个感染指标水平差异，用受试者工作曲线（ROC）分析四个感染指标在早期血流感染中的诊断价值。结果　血培养阳性组患者血清PCT， IL-6，SAA及hs-CRP水平高于对照组1.10（0.29，8.27）ng/ml vs 0.01（0.01，0.01）ng/ml, 75.20（33.30, 359.80）pg/ml vs2.00（2.00, 2.00）pg/ml, 148.10（77.15, 200.00）mg/L vs 5.00（5.00, 6.56）mg/L和93.20(44.23, 158.07)mg/L vs 0.63（0.34,1.32）mg/L]，差异均有统计学意义（Z =-9.213～-9.472，均P<0.001）。ROC曲线分析，PCT, IL-6，SAA及 hs-CRP在诊断血流感染中的曲线下面积（AUC）分别为0.975，0.981，0.965和0.982（P<0.001）。数据分析发现血清PCT及SAA水平在革兰阴性菌组高于革兰阳性菌组2.04（0.38, 21.60）ng/ml vs 0.60（0.17，2.75）ng/ml, 186.24（90.61，200.00）mg/L vs 104.49(44.94，200.00) mg/L]，差异均有统计学意义（Z = -3.107，-2.688，均P<0.05）。PCT，SAA及PCT联合SAA在鉴别革兰阴性菌与革兰阳性菌感染中的ROC曲线下面积为0.663, 0.644和0.708（均P<0.05）。结论　血清PCT, IL-6，SAA及hs-CRP可以为快速鉴别早期血流感染提供较好的实验依据，尤其PCT与SAA联合在鉴别革兰阴性菌与革兰阳性菌感染中有一定的诊断价值。

Clinical Application Values of Procalcitonin,Interleukin-6, Serum Amyloid Aand Hypersensitive of C-reactive Protein Detections in the Diagnosis ofEarly Bloodstream Infection

Objective　To investigate the clinical application value of serum procalcitonin (PCT), interleukin-6 (IL-6), serumamyloid protein (SAA) and hypersensitive C-reactive protein (hs-CRP) in rapid diagnosis of early bloodstream infection.Methods　A total of 119 patients with positive blood culture, including 45 cases of gram-positive bacterial infection and 72casesof gram-negative bacterial infection, and 44 healthy controls in the hospital from March 2018 to August 2020 were enrolled asthe subjects in this study. The serum samples of patients on the day of blood culture were collected and frozen at -80 ℃ . Theserum levels of PCT, IL-6, SAA and hs-CRP were measured respectively. The differences of the measured results among thevarious groups were statistically analyzed. In order to estimate the clinical performance of these biomarker assays in earlybloodstream infections, receiver operating characteristic (ROC) analyses were performed and comparison of the areas under thecurve were analyzed. Results　The serum levels of PCT, IL-6, SAA and hs-CRP in positive blood culture group weresignificantly higher than those in healthy control group 1.10（0.29,8.27）ng/ml vs 0.01（0.01,0.01）ng/ml, 75.20（33.30,359.80）pg/ml vs 2.00（2.00,2.00）pg/ml, 148.10（77.15,200.00）mg/L vs 5.00（5.00,6.56）mg/L, 93.20(44.23, 158.07) mg/L vs 0.63（0.34,1.32）mg/L]，the differnce were statistically significant (Z =-9.213 ～ -9.472，all P<0.001). The ROC curve analysisshowed that the area under the curve of PCT, IL-6, SAA and hs-CRP for the diagnosis of bloodstream infections were 0.975,0.981, 0.965 and 0.982 respectively（P <0.001）. Data analysis found that the levels of PCT and SAA in Gram-negative bacteriagroup were significantly higher than those in Gram-positive bacteria group 2.04（0.38,21.60）ng/ml vs 0.60（0.17,2.75）ng/ml, 186.24（90.61,200.00）mg/L vs 104.49(44.94, 200.00) mg/L], the difference were statistically significant(Z= -3.107,-2.688, all P<0.05). The AUC of PCT, SAA and the combined detections of PCT and SAA in distinguishing Gram-negativebacteria group from Gram-positive bacteria group were 0.663, 0.644 and 0.708, respectively. Conclusion　The serum levels ofPCT, IL-6, SAA and hs-CRP can provide a good experimental basis for the rapid identification of early bloodstream infections. Inparticular, the combined detections of PCT and SAA have a certain diagnostic value in distinguishing Gram-negative bacterialinfection from Gram-positive bacterial infection.