尿沉渣定量检测白细胞及细菌总数对尿路感染的诊断价值

Diagnostic value of quantitative detection of leukocytes and bacteria in the urine sediment of urinary tract infection

目的探讨尿沉渣中白细胞及细菌定量计数对尿路感染的诊断价值。方法选取2014年2~11月在海南医学院第二附属医院住院疑似尿路感染患者436例尿液标本作为观察组,80例我院健康体检人员尿液标本作为对照组,均留取清洁中段尿同时做细菌培养和用Cobio XS尿沉渣分析仪进行定量检测。以尿培养为金标准,制作尿沉渣白细胞及细菌定量检测诊断尿路感染的ROC曲线,利用SPSS19.0软件绘制ROC曲线,评价预测价值,并计算其灵敏度、特异性、阳性预测值、阴性预测值和准确度。结果观察组患者的尿沉渣细菌和白细胞阳性率分别为40.14%和33.26%,对照组分别为6.25%和5.00%,观察组明显高于对照组,差异均有统计学意义(P<0.05);在436份尿液标本中,培养阳性118例占27.1%;以尿白细胞和细菌量作为诊断的ROC曲线下面积分别为0.786、0.820,临界值分别为13个/μL(白细胞)、111个/μL(尿细菌数);Cobio XS分析白细胞筛查的灵敏度为76.3%、特异性为82.7%、阳性预测值为62.1%,阴性预测值为90.4%、假阳性率为17.3%、假阴性率为23.7%。Cobio XS分析细菌的灵敏度为84.7%、特异性为76.7%、阳性预测值为57.5%,阴性预测值为93.1%、假阳性率为23.3%、假阴性率为15.3%。结论 Cobio XS尿全自动化分析仪检测尿液中白细胞及细菌数用于临床尿路感染的诊断具有简便快速、符合率高、成本低等优点,但还存在一定量的假阳性和假阴性结果,仍不能替代尿培养,可在一定程度上对大多数阴性者得以筛除。

Objective To explore the diagnostic value of quantitative detection of leukocytes and bacteria in urine sediment of urinary tract infection. Methods Four hundred and thirty six urine specimens from patients with suspected urinary tract infection hospitalized in our hospital from Feb. 2014 to Nov. 2014 were investigated as an observation group, and 80 urine specimens from healthy people who underwent health examination in our hospital were enrolled as a control group. All of these clean-catch midstream urine specimens were processed using bacterial culture and quantitative detection by Cobio XS urine sediment analyzer. Using urine culture as gold standard, ROC curves for leukocytes and bacteria were calculated to detect urinary tract infection by using SPSS19.0 software. ROC curve analysis was performed to evaluate predictive values and calculate sensitivity, specificity, positive predictive value, negative predictive value and accuracy. Results The positive rates of urine sediment bacteria and leukocytes in observation group were40.14% and 33.26%, significantly higher 6.25% and 5.00% in control group respectively（P〈0.05）. 118 of 436 specimens were positive for uropathogen, accounting for 27.1%. The area under the ROC curve were 0.786 for white blood cell（WBC） and 0.820 for bacteria, and cut-off concentrations were 13 cells/μL（WBC） and 111 cells/μL（urine bacteria） respectively. Cobio XS analysis for WBC indicated a sensitivity of 76.3%, specificity of 82.7%, positive predictive value of 62.1%, negative predictive value of 90.4%, false-positive rate of 17.3% and false-negative rate of 23.7%. Cobio XS analysis for bacteria showed a sensitivity of 84.7%, specificity of 76.7%, positive predictive value of 57.5%, negative predictive value of 93.1%, false-positive rate of 23.3% and false-negative rate of 15.3%. Conclusion Cobio XS automated urine sediment analyzer which is capable of quantifying urine leukocytes and bacteria is used in the diagnosis of urinary tract infection with advantages of simple, rapid, high coincidence rate and low cost, while it can also create a number of false-positive and false-negative results. Thus urinalysis can＇t substitute for a urine culture, but is to some extent used to filter out most of the negative results.