降钙素原在鉴别血流感染菌种中的作用

Role of procalcitonin in identifying bloodstream infection of microorganism strains in patients

目的比较血清降钙素原(PCT)在G-杆菌和G+球菌血流感染中的差异及其诊断价值。方法回顾性分析本院急诊科血流感染患者,血培养结果阳性且为单一的G-杆菌或G+球菌菌株,并检测了血清PCT浓度,所有患者的疾病严重程度通过APACHEII评分、SOFA评分、住院时间、死亡率来评价。根据菌株不同分为G-杆菌感染组(59例)、G+球菌感染组(24例)。比较2组患者入院时的PCT水平。绘制PCT对血流感染菌种鉴别的受试者工作特征曲线(ROC曲线),根据曲线下面积(AUC)来评价其对血流感染菌种鉴别的价值。结果 G-杆菌和G+球菌2组血流感染患者在年龄、性别、疾病严重程度、住院时间方面比较差异无统计学意义(P>0.05)。2组血流感染患者的感染来源比较差异具有统计学意义(P<0.05);G-杆菌感染多来源于消化系统,G+球菌感染多来源于呼吸系统。从血液培养的菌株分布来看,引起血流感染的G-杆菌以大肠埃希氏菌、肺炎克雷伯氏菌为主,G+球菌以金黄色葡萄球菌、溶血性葡萄球菌为主。G-杆菌组PCT高于G+球菌组,差异有统计学意义(P<0.05)。ROC曲线分析显示,PCT曲线下面积AUC=O.680(95%CI:0.555-0.806)、AUC与area=0.5的差异具有统计学意义(P<0.05);血清PCT值的最佳截断值为2.5 ng/m L,此时Youden指数最大(0.309),灵敏度为55.9%,特异度为70.5%。结论血清PCT浓度在G-杆菌引起血流感染中明显增高,故早期检测有诊断意义。

Objective To explore the differences of serum procalcitonin（ PCT） between Gram- negative（ GN） and Gram- positive（ GP） bacterial bloodstream infection（ BSI） and its diagnostic value. Methods The levels of PCT of patients were retrospectively investigated in emergency department. The patients with consistent positive blood culture were enrolled in this study,including59 cases with GN bacterial infection and 24 cases with GP bacterial infection. And the concentration of serum PCT was detected. Clinical data such as APACHEII,SOFA score,hospitalization duration and mortality were recorded. We analyzed the difference of PCT level of GN and GP groups. ROC curve was drawn according diagnostic value of PCT in discriminating between GN and GP bacterial bloodstream infection and AUC was applied to assess the value of identifying bloodstream infection of microorganism strains. Results There were no differences in gender,age,APACHEII,SOFA score,hospitalization duration and mortality between two groups（ P 0. 05）. Infection sources of two groups showed statistically significant difference（ P 0. 0 5）. Gram- negative bacillus was mainly infected by digestive system and Gram- positive cocci was sourced from respiratory system. E.coli and pneumonia Klebsiella were identified as the most frequent causal pathogens leading to bloodstream infection in Gram- negative bacillus. Staphylococcus aureus and staphylococcus haemolyticus were the most frequent causal pathogens in Gram- positive cocci.PCT levels in Gram- negative bacillus group were found to be markedly higher than that in Gram- positive cocci group,there was statistically significant difference（ P 0. 05）. Receptor of curve（ ROC） revealed that the area under the curve（ AUC） was 0. 680（ 95% CI： 0. 555-0. 806）,which was found a statistically significant difference between AUC and area = 0. 5（ P 0.05）. Taken 2. 5 ng / m L as a cut- off value of PCT,we found the largest Youden index was 0. 309.The sensitivity was 55. 9% and the specificity was 70. 5%. Conclusion PCT concentration is increased in bloodstream infection,so early diagnosis is of great value.