Midstream urine culture is regarded as the gold standard for diagnosing urinary tract infection (UTI). However, drug sensitivity analysis through bacterial culture and strain identification takes a substantial period to produce the final report, usually in 5–7 days. Therefore, it fails to timely provide valuable information for clinical work in the early stage of disease. Without in time treatment, UTI will lead to serious consequences such as sepsis, uremia and renal failure. Therefore, early diagnosis and timely treatment of UTI are of great importance [1,2]. Clinicians usually depend on dry chemical analysis results of urine to predict the occurrence of UTI. The instruments of Sysmex company, such as UF-500i and UF-1000i, have shown excellent performance in screening UTI [[3], [4], [5]].

Combination of UC-3500 and UF-5000 designed by Sysmex Corporation in 2017. UF-5000 is based on fluorescence flow cytometry, just like UF-500i and UF-1000i. But significant changes have been made in the detection channel and reagents, and the light source has also been increased [[6], [7], [8]]. It is worth noting that UF-5000 differs from UF-500i and UF-1000i which only indicate “cocci” and “bacilli” in the alarm message of urinary tract infection. UF-5000 is an analyzer to detect urine bacterium and can produce “Gram-positive bacteria” or “Gram-negative bacteria” (BACT)-info flag information. This alarm message provides more intuitive information to identify the bacteria type in clinical practice. At present, the performance of UF-5000 for rapid screening of UTI has been evaluated in many studies. The results showed that UF-5000 could effectively screen the bacterial culture of urine specimens by selecting the appropriate cut-off value of WBC count and bacterial count. There was a significant concordance between the positive results of bacterial classification and bacterial culture [[9], [10], [11], [12], [13]]. At present, few research on the comprehensive analysis using a quick and effective screening strategy have been found.

On this basis, we formulated several screening strategies to evaluate the accuracy of UF-5000 bacterial classification formed by UF-5000 and UC-3500 and further explored the appropriate screening strategies, with the view of providing more intuitive and accurate information for clinical treatment of UTI.