阳性报警时间对成人凝固酶阴性葡萄球菌颅内感染鉴别诊断研究

Time to positivity in differential diagnosis of intracranial infection caused by coagulase-negative Staphylococcus

目的探讨阳性报警时间（TTP）对凝固酶阴性葡萄球菌（CNS）颅内感染鉴别诊断应用价值。方法回顾性分析中南大学湘雅医院2015年1至12月脑脊液培养出凝固酶阴性葡萄球菌成人患者124例，分为颅内感染组（n＝70）和脑脊液培养污染组（n＝54）。比较颅内感染组和脑脊液培养污染组TTP的差异，绘制受试者工作特征（ROC）曲线，计算ROC曲线下的面积（AUC），同时比较不同种类CNS阳性患者的TTP。采用SPSS18.0统计软件对数据进行分析。结果颅内感染组患者TTP为（23.5±7.5 ） h，而CSF培养污染组TTP为（37.6±10.5） h，两组TTP比较差异具有统计学意义（t＝－8.717，P＝0.000）。TTP的AUC为0.854，当TTP临界值取27.94 h时，敏感性为72.7%，特异度为91.4%，阳性预测值为90.0%，阴性预测值为72.2%。表皮葡萄球菌、溶血葡萄球菌、头状葡萄球菌引起的颅内感染与脑脊液培养污染相比，TTP差异有统计学意义（Z＝－4.496、－2.322和－2.399，P〈0.05或〈0.01）。结论TTP有助于早期鉴别诊断CNS引起的颅内感染和样本污染，对于不同类型CNS造成的颅内感染也有一定鉴别意义。

Objective To evaluate the application of time to positivity （TTP） in differential diagnosis of intracranial infection caused by coagulase-negative Staphylococcus （ CNS ）. Methods One hundred and twenty-four adult patients with positive CNS isolated from cerebrospinal fluid （CSF） including 70 cases with intracranial infection and 54 cases of CSF contamination, who were admitted in Xiangya Hospital of Central South University during January to December 2015, were retrospectively analyzed. The difference of TTP between two groups was compared, receiver operating characteristic （ ROC ） curve was analyzed and the area under the ROC curve （ AUC ） was calculated. The application of TTP in differential diagnosis of CNS infection was evaluated. SPSS 18.0 software was used to analyze the data. Results TFP in intracranial infection group was shorter than that in CSF contamination group [ （23. 5 ±7. 5 ） h vs. （37.6±10.5） h, t = -8.717,P=0.000]. The AUC of TTP was 0.854. Taking the cut-off value of 27.94 h,the sensitivity, specificity, positive and negative predictive values in differentiation of two groups were 72.7% , 91.4% , 90.0% and 72.2% , respectively. There were statistically differences in TTP of Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus capitis between two groups （Z = -4.496, -2.322 and -2. 399,respectively, P 〈0.05 or 〈0.01）. Conclusion TTP can be used to discriminate early intracranial infection and CSF contamination caused by CNS, and also can identify intracranial infection caused by different categories of CNS.