中枢神经系统医疗器械植入患者脑脊液分离凝固酶阴性葡萄球菌真感染诊断值的确定与临床意义

Determination of laboratory indicators and clinical significance of coagulasenegative staphylococci true infection in cerebrospinal fluid of patients implanted with central nervous system medical devices

目的凝固酶阴性葡萄球菌(coagulase negative staphylococci,CoNS)是神经外科术后脑脊液最常见的分离菌,研究医疗器械植入患者脑脊液分离CoNS的真感染率,并寻找区分CoNS的感染和污染的实验室有效指标。方法回顾性分析2020年1月—2021年6月航空总医院神经外科住院患者71例,均行医疗器械植入后感染CoNS者,采用传统脑脊液培养、鉴定及药物敏感性检测,按专家共识标准分CoNS感染组与污染组,利用统计学的t检验和u检验比较判断感染组与污染组的9项实验室指标的差异,绘制ROC曲线,比较AUC,得出最佳分界值及相应的敏感性与特异性等。结果共收集238例纳入患者的脑脊液标本,医疗器械植入后患者脑脊液培养CoNS阳性71例,其中真感染34例,污染37例,真感染率为47.89%。感染组与污染组的其他实验室感染指标包括脑脊液培养报阳时间(h)[16.68(11.94,24.33),30.00(16.56,34.80),Z=-2.781,P=0.005]、脑脊液葡萄糖浓度/血葡萄糖浓度比值(0.41±0.15,0.57±0.15,t=-3.991,P=0)、脑脊液白细胞计数(×10^(6)/mL)[71.00(19.00,451.00),10.00(4.50,92.50),Z=-2.867,P=0.004]、脑脊液葡萄糖浓度(mmol/L)[2.66(1.81,3.46),3.19(2.66,4.01),z=-1.994,P=0.046]、血葡萄糖浓度(mmol/L)[5.81(5.28,6.64),5.09(4.84,6.19),z=-2.644,P=0.008]等差异具有统计学意义(P<0.05);ROC曲线显示脑脊液培养报阳时间和脑脊液葡萄糖浓度/血葡萄糖浓度比值的AUC均大于0.7,最佳分界值分别为29.76 h和0.54,敏感性分别为96.2%和90.6%,特异性分别为56.2%和68.2%,脑脊液培养报阳时间+脑脊液葡萄糖浓度/血葡萄糖浓度比值联合检测的AUC大于0.8,诊断效能最好。结论医疗器械植入患者脑脊液分离CoNS的真感染率为47.89%;临床诊治需综合其他感染指标,脑脊液培养报阳时间和脑脊液葡萄糖浓度/血葡萄糖浓度比值联合检测可作为鉴别感染与污染的较好参考指标。

Objective Coagulase negative staphylococci(CoNS)is the most common isolate of cerebrospinal fluid in patients who are undergoing neurosurgery.To study the true infection rate of CoNS isolated from cerebrospinal fluid in patients with medical device implantation,and to find laboratory indicators to distinguish between infection and contamination of CoNS.Methods We retrospectively analyzed 71 inpatients in the Department of Neurosurgery of Aviation General Hospital from January 2020 to June 2021,all of whom were infected with CoNS after the implantation of medical devices.Traditional cerebrospinal fluid culture,identification and antimicrobial susceptibility testing of bacteria were performed.According to expert consensus standards,the CoNS infection group and the contamination group were divided,and the statistical T test and U test were used to compare the nine laboratory indicators between the infection group and the contamination group.ROC curve was drawn,and AUC,best diagnostic value,corresponding sensitivity and specificity were compared.Results A total of 238 cases of cerebrospinal fluid were collected.After medical device implantation,there were 71 cases of cerebrospinal fluid cultured CoNS,including 34 cases of true infection and 37 cases of contamination,with a true infection rate of 47.89%.The following laboratory indicators exhibited significantly differences between the infection group and contamination group:cerebrospinal fluid culture positive time(h)[16.68(11.94,24.33),30.00(16.56,34.80),z=-2.781,P=0.005],cerebrospinal fluid glucose concentration/blood glucose concentration(0.41±0.15,0.57±0.15,t=-3.574,P=0.000),cerebrospinal fluid leukocyte count(×10^(6)/mL)[71.00(19.00,451.00),10.00(4.50,92.50),z=-2.867,P=0.004],cerebrospinal fluid glucose concentration(mmol/L)[2.66(1.81,3.46),3.19(2.66,4.01),z=-1.994,P=0.046]and blood glucose concentration(mmol/L)[5.81(5.28,6.64),5.09(4.84,6.19),z=-2.644,P=0.008].The ROC curve showed that the AUC of cerebrospinal fluid culture positive time and cerebrospinal fluid glucose concentration/blood glucose concentration ratio were greater than 0.7,and their best cut-off values were 29.76 h and 0.54,sensitivities were 96.2%and 90.6%,specificities were 56.2%and 68.2%,respectively.Moreover,the diagnostic accuracy of combined examination with cerebrospinal fluid culture positive time and cerebrospinal fluid glucose concentration/blood glucose concentration ratio was the best,with an AUC greater than 0.8.Conclusion The true infection rate of CoNS isolated from cerebrospinal fluid in patients with medical device implantation was 47.89%;Clinical diagnosis and treatment need to integrate other infection indexes.The combined detection of cerebrospinal fluid culture positive time and cerebrospinal fluid glucose concentration/blood glucose concentration ratio can be used as a reference index to distinguish infection and contamination of CoNS.