Karakukcu C, Kayman T, Ozturk A, Torun Y A
Training and Research Hospital, Department of Clinical Biochemistry, Kayseri, Turkey.
Clin Lab. 2012;58(1-2):107-11.
Urine analysis is one of the most common tests for assessing urinary-tract infections, which are the most frequently occurring infectious diseases in community populations. Urine culture is still the 'gold standard' for the detection of urinary tract infection, however, it is time- and labor-intensive and and has a high number of unnecessary cultures. The aim of this study was to evaluate the analytical and diagnostic performance of a new urinalysis system LabUMat with UriSed (77 Elektronika, Budapest, Hungary) in comparison to urine culture as the reference method.
By comparing the test results for 965 urine samples with quantitative urine cultures, we established cutoff criteria for the UriSed. The cut-off values by the receiver operating characteristic (ROC) curve technique, sensitivity, and specificity were calculated for bacteria (BACT) and white blood cells (WBCs).
A bacterial cutoff value of 375/microL provided the best discrimination for community-acquired urinary tract infection, with a sensitivity of 96.5% and a specificity of 82.1% compared with 182 urine culture positive samples (AUC: 0.939). It was possible to forgo 62.6% of cultures with only 8 false-negative results. The best cut-off value for WBCs was 13/microL. When we used an algorithm in which the combination with the positivity for 85 BACT/microL and for 13 WBCs/microL count, the sensitivity and NPV improved to 99.8% and 100%, respectively, but the specificity declined from 78.8% to 52.0%.
When screening with the UriSed for community-acquired urinary tract infection, a cut-off value of 85 bacteria/microL and 13 WBCs/microL should be adopted. Diagnostic performance of UriSed is satisfactory and use of this instrument is a reliable method for screening out a major part of the culture negative samples. It would improve the efficiency of microbiology laboratory, and unnecessary antibiotic prescriptions could be reduced.
尿液分析是评估尿路感染最常用的检测方法之一，尿路感染是社区人群中最常见的传染病。尿培养仍然是检测尿路感染的“金标准”，然而，它耗时费力，且存在大量不必要的培养。本研究的目的是评估一种新的尿液分析系统LabUMat与UriSed（匈牙利布达佩斯77 Elektronika公司）相对于作为参考方法的尿培养的分析和诊断性能。
通过将965份尿液样本的检测结果与定量尿培养结果进行比较，我们确定了UriSed的截断标准。采用受试者操作特征（ROC）曲线技术计算细菌（BACT）和白细胞（WBC）的截断值、敏感性和特异性。
细菌截断值为375/μL时，对社区获得性尿路感染的鉴别效果最佳，与182份尿培养阳性样本相比，敏感性为96.5%，特异性为82.1%（AUC：0.939）。仅8例假阴性结果的情况下，可以省去62.6%的培养。白细胞的最佳截断值为13/μL。当我们使用一种算法，将85 BACT/μL和13 WBC/μL计数的阳性结果相结合时，敏感性和阴性预测值分别提高到99.8%和100%，但特异性从78.8%降至52.0%。
使用UriSed筛查社区获得性尿路感染时，应采用85个细菌/μL和13个白细胞/μL的截断值。UriSed的诊断性能令人满意，使用该仪器是筛选出大部分培养阴性样本的可靠方法。它将提高微生物实验室的效率，并减少不必要的抗生素处方。
