Department of Emergency Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Department of Anesthesiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Dis Markers. 2019 Mar 3;2019:5853486. doi: 10.1155/2019/5853486. eCollection 2019.
Bacterium and leucocyte counts in urine can be measured by urine flow cytometry (UFC). They are used to predict significant bacterial growth in urine culture and to diagnose infections of the urinary tract. However, little information is available on appropriate UFC cut-off values for bacterium and leucocyte counts in specific clinical presentations.
To develop, validate, and evaluate adapted cut-off values that result in a high negative predictive value for significant bacterial growth in urine culture in common clinical presentation subgroups.
This is a single center, retrospective, observational study with data from patients of the emergency department of Bern University Hospital, Switzerland, with suspected infections of the urinary tract. The patients presented with different symptoms, and urine culture and urine flow cytometry were performed. For different clinical presentations, the patients were grouped by (i) age (>65 years), (ii) sex, (iii) clinical symptoms (e.g., fever or dysuria), and (iv) comorbidities such as diabetes and immunosuppression. For each group, cut-off values were developed, validated, and analyzed using different strategies, i.e., linear discriminant analysis (LDA) and Youden's index, and were compared with known cut-offs and cut-offs optimized for sensitivity.
613 patients were included in the study. Significant bacterial growth in urine culture depended on clinical presentation and ranged from 32.3% in male patients to 61.5% in patients with urinary frequency. In all clinical presentations, the predictive accuracy of UFC leucocyte and UFC bacterium counts was good for significant bacterial growth in urine culture (AUC ≥ 0.88). The adapted LDA equations did not exhibit consistently high sensitivity. However, the in-house cut-offs (test positive if UFC leucocytes > 17/L or UFC bacteria > 125/L) were highly sensitive (>90%). In female, younger, and dysuric patients, even higher cut-offs for UFC leucocytes (169/L, 169/L, and 205/L) exhibited high sensitivity. Specificity was insufficient (<0.9) for all tested cut-offs.
For various clinical presentations, significant bacterial growth in urine culture can be excluded if flow cytometry measurements give a bacterial count of ≤125/L or a leucocyte count of ≤17/L. In female patients, dysuric patients, and patients younger than ≤65 years, the leucocyte cut-off can be increased to 170/L.
尿液流式细胞术（UFC）可用于测量尿液中的细菌和白细胞计数。这些计数可用于预测尿液培养中细菌的大量生长，并诊断尿路感染。然而，对于特定临床表现中细菌和白细胞计数的适当 UFC 截止值，相关信息很少。
开发、验证和评估适用于常见临床表现亚组的尿培养中细菌大量生长的高阴性预测值的改良截止值。
这是一项单中心、回顾性、观察性研究，数据来自瑞士伯尔尼大学医院急诊科疑似尿路感染的患者。这些患者表现出不同的症状，并进行了尿液培养和尿液流式细胞术检测。对于不同的临床表现，根据（i）年龄（>65 岁）、（ii）性别、（iii）临床症状（如发热或尿痛）以及（iv）合并症（如糖尿病和免疫抑制）对患者进行分组。对于每个组，使用不同的策略（即线性判别分析（LDA）和 Youden 指数）来开发、验证和分析截止值，并将其与已知截止值和为提高敏感性而优化的截止值进行比较。
共有 613 名患者纳入研究。尿液培养中细菌的大量生长取决于临床表现，范围从男性患者的 32.3%到尿频患者的 61.5%。在所有临床表现中，UFC 白细胞和 UFC 细菌计数对尿液培养中细菌的大量生长具有良好的预测准确性（AUC≥0.88）。经改良的 LDA 方程并未表现出始终较高的敏感性。然而，内部制定的（UFC 白细胞>17/L 或 UFC 细菌>125/L 时为阳性）截止值具有很高的敏感性（>90%）。在女性、年轻和尿痛患者中，即使 UFC 白细胞的截止值（169/L、169/L 和 205/L）更高，也具有较高的敏感性。所有测试截止值的特异性均不足（<0.9）。
对于各种临床表现，如果流式细胞术测量结果细菌计数≤125/L 或白细胞计数≤17/L，则可排除尿液培养中细菌的大量生长。在女性患者、尿痛患者和年龄≤65 岁的患者中，白细胞的截止值可增加到 170/L。
