摘要
目的：评估血培养阳性时间差法（DTTP）对重症加强治疗病房（ICU）实体肿瘤患者静脉导管相关性血流感染（CRBSI）诊断的应用价值。方法采用回顾性病例对照研究方法，收集2011年8月至2014年3月天津医科大学肿瘤医院ICU送检的615例患者615对中心静脉导管血和外周静脉血培养标本，采用DTTP法和（或）导管尖端半定量培养法进行培养。中心静脉导管与外周静脉血培养分离出相同病原菌且DTTP≥2 h（120 min）时诊断为CRBSI；导管尖端半定量培养菌落数≥15 cfu诊断为CRBSI。以临床诊断为依据，比较DTTP和导管尖端半定量培养两种实验室检查方法对CRBSI诊断的可靠性；并绘制受试者工作特征曲线（ROC），评估两种方法单用或联用对CRBSI的诊断价值。结果615例患者配对血培养标本中，有440例因外周静脉和中心静脉导管血培养皆为阴性而被排除CRBSI；有8例外周静脉血培养阳性而中心静脉导管血培养阴性，提示导管为非感染源；有57例中心静脉导管血培养阳性而外周静脉血培养阴性而被排除；有68例因多处留置导管和重复采集标本而被排除。42例中心静脉导管和外周静脉血培养均为阳性的标本中，有2例因检出不同菌种被排除，有10例因没有导管尖端标本送检被排除，13例确诊为非CRBSI。在17例确诊为CRBSI的配对中心静脉导管和外周静脉血培养标本中，有14例患者中心静脉导管和外周静脉配对血培养DTTP≥120 min，漏诊3例；而导管尖端半定量培养法阳性者有13例，漏诊4例；其中有2例患者同时被两种方法漏诊。DTTP法与导管尖端培养法单用及联用诊断CRBSI的ROC曲线下面积（AUC）分别为0.912、0.882和0.941。单用DTTP法诊断CRBSI的敏感度、特异度、阳性预测值和阴性预测值分别为82.35%、92.31%、93.33%和80.00%，均高于单用导管尖端培养法（分别为76.47%、84.62%、86.67%和73.33%）；而两种方法联合诊断CRBSI的特异度和阳性预测值可达100%，敏感度（88.24%）和阴性预测值（86.67%）也有所提高，但与单独应用DTTP法比较差异无统计学意义（χ^2＝0.00，P＝1.00；χ^2＝0.00，P＝0.98；χ^2＝0.00，P＝0.98；χ^2＝0.00，P＝0.98）。结论 DTTP法诊断ICU实体肿瘤患者CRBSI具有可接受的敏感度及较好的特异度和阳性预测值，可推荐用于辅助诊断CRBSI；如将DTTP与其他临床症状结合并进行综合分析，不仅可避免不必要的导管移除，也可帮助患者及时获得最佳治疗时间和方案。
Objective To determine the value of differential time to positivity （ DTTP ） of blood culture for the diagnosis of catheter-related bloodstream infection （ CRBSI ） in patients with solid tumors in intensive care unit （ ICU ）. Methods A retrospective study was conducted. 615 pairs of peripheral vein blood cultures and instantaneous catheter tip blood culture of 615 patients admitted to ICU of Tianjin Medical University Cancer Institute and Hospital were collected from August 2011 to March 2014. The DTTP method and （ or ） semi quantitative culture of catheter tip were compared. CRBSI was diagnosed when both cultures were positive for the same microorganism and DTTP ≥2 hours （ 120 minutes ）. The result of this procedure was compared with that of organism obtained using the semi quantitative culture of blood at catheter tip with≥15 cfu. Based on the clinical diagnosis, the reliability of two kinds of laboratory examination was compared for the diagnosis of CRBSI by plotting receiver operator characteristic curve （ ROC curve ）. Results The result of 615 cases suspected of having CRBSI were analyzed during the study period. Of these, 440 episodes were excluded because cultures were negative for blood obtained through peripheral vein and central vein. Eight episodes were excluded because only peripheral vein blood culture was positive and 57 episodes were excluded because of only central vein blood culture was positive, 68 pairs of blood cultures were excluded due to the presence of multiple catheters and repeated blood withdrawals. Two cases of polymicrobial cultures were excluded from the final analysis due to the difficulty in determining the time of positive result for each individual microorganism. Ten cases in 42 cases of suspected cases of CRBSI were excluded from analysis because catheter was not removed, therefore culture from catheter tip could not be obtained. Using the DTTP method, 14 out of 17 CRBSI cases were diagnosed with DTTP≥120 minutes, while 3 cases were missed;the semi quantitative catheter tip culture was positive in 13 cases, and in 4 cases it was neglected. In 2 cases of CRBSI it was missed by both methods. The area under the ROC curve （ AUC ） of DTTP, catheter tip culture and the combination method was 0.912, 0.882 and 0.941 for diagnosis of CRBSI, respectively. Validity values for the diagnosis of CRBSI for DTTP were：sensitivity 82.35%, specificity 92.31%, positive predictive value 93.33%and negative predictive value 80.00%, and they were higher than those of the catheter tip culture method only （ 76.47%, 84.62%, 86.67% and 73.33%）. The specificity and positive predictive CRBSI combination of the two methods in the diagnosis value were up to 100%, the sensitivity （ 88.24%） and negative predictive value （ 86.67%） was also increased, but no significant differences were found with DTTP method （χ^2=0.00, P=1.00;χ^2=0.00, P=0.98;χ^2=0.00, P=0.98;χ^2=0.00, P=0.98 ）. Conclusions DTTP can be a valid method recommended for CRBSI diagnosis in critically ill patients with acceptable sensitivity, good specificity as well as positive predictive value. DTTP combined with other clinical symptoms can not only avoid unnecessary catheter withdrawal, but it also can help obtain the optimal treatment time and strategy.
出处
《中华危重病急救医学》
CAS
CSCD
北大核心
2015年第6期489-493,共5页
Chinese Critical Care Medicine
基金
国家高技术研究发展计划（863）项目（2011AA02A111）
关键词
导管相关性血流感染
实体肿瘤
阳性时间差
导管半定量培养
Catheter-related bloodstream infection
Solid tumor
Differential time to positivity
Semi quantitative catheter tip culture
