尿液細菌培養陽性結果為泌尿道感染的確診指標，執行時非常耗時費工。本研究目的為探討常規尿液檢驗之自動尿液流式細胞分析是否可成為泌尿道細菌感染之快速篩檢工具。自2015年10月至2016年7月期間，分析急診、門診與住院病患之同時執行尿液常規檢驗與尿液細菌培養檢驗的案例共9,951件。尿液細菌培養至少一種菌落大於1×105 CFU/mL時，判定為陽性結果且設為黃金標準，比對Sysmex UF-1000i自動化尿沉渣分析儀之尿液細菌分析相關資訊與黃金標準法的檢驗報告結果，於9,951件尿液檢體中，共1,356（13.6%）例細菌培養陽性。以Sysmex UF-1000i細菌數之結果進行特徵曲線(receiver operating characteristic curve, ROC曲線)分析。最佳切點之細菌計數值為283.6 bacteria /μL，曲線下面積(area under curve, AUC)為0.929，其敏感度為0.850、特異性為0.883、準確度為0.878、陽性預測值為0.533、陰性預測值為0.973，研究結果顯示此條件參數對於排除細菌感染具有高準確性。比較儀器預設之泌尿道感染警訊’’Bacterial morphology flag’’ (細菌數高於100 bacteria/μL且白血球計數高於10 WBCs/μL)，其敏感度為0.870、特異性為0.832、準確度為0.837、陰性預測值則為0.976，但其陽性預測值僅為0.450。隨著細菌價數提高，其陽性預測值可隨之升高，但敏感度亦隨之降低。綜合相關統計條件，建議以Sysmex UF-1000i自動尿液流式細胞分析儀細菌數值低於283.6 bacteria /μL時為排除泌尿道細菌感染的功能性指標。

Urinary tract infection (UTI) is the most common bacterial infection in humans, and its diagnosis by urine culture is expensive and time-consuming. The study was aimed to evaluate the diagnostic utility of Sysmex UF-1000i. We analyzed 9,951 cases with the results of urinalysis and concurrent bacterial culture from October, 2015 to July, 2016. In total, 1,356 (13.6%) urine specimens showed positive bacterial cultures using the gold standard with a cut-off value of 1x105 CFU/mL. Based on the analysis of 9,951 urine samples by receiver operating characteristic curve with an area under curve of 0.929, the best cut-off value is 283.6 bacteria /μL. The sensitivity, specificity, accuracy and negative predictive value (NPV) were 0.85, 0.88, 0.87 and 0.97, respectively, while the positive predictive value (PPV) was 0.53. Bacterial morphology flags are given by the urine flow cytometer Sysmex UF-1000i when the quantitative results of bacteria and WBC exceed the thresholds of 100/mL and 10/mL, respectively. Evaluation of the bacterial morphology flags with 9,951 cases demonstrated the sensitivity and NPV were 0.87 and 0.97, respectively, while the specificity, accuracy and PPV were 0.83, 0.83, and 0.45, respectively. As the cut-off value increasing, the PPV increases while the NPV decreases. Taken together, the 283.6 bacteria /μL analyzed by Sysmex Uf-1000i could be a better tool than its bacterial morphology flag to rule out UTI.