Optimizing urinary tract infection diagnosis: time and resource efficiency with the Sysmex UF-4000i

Abstract

Background: Urinary Tract Infections (UTIs) are common bacterial infections, primarily caused by Gram-negative bacteria, such as Escherichia coli. They affect approximately 150 million individuals worldwide annually, leading to high healthcare costs and significant morbidity. The standard diagnostic method, urine culture, has a turnaround time of 48-72 hours, often necessitating empirical antibiotic treatment, which may contribute to antibiotic resistance. Rapid, accurate diagnostic tools are essential to improve clinical microbiology practices. Materials and Methods: this study evaluated the diagnostic accuracy of the Sysmex UF4000i flow cytometer for UTI detection, using traditional microscopy as the reference standard. Conducted over eight months at the Institut Pasteur, Dakar, it involved 2,322 urine samples analyzed via cytological examination and flow cytometry within two hours of collection. Bacterial cultures were performed on Chromagar Orientation media. Diagnostic performance was assessed using Receiver Operating Characteristic (ROC) curve analysis to establish a bacteriuria threshold for excluding UTIs. Results: among the 2,322 samples, bacteriuria was detected in 16.3%, with E. coli accounting for 60.7% of positive cultures. The Sysmex UF4000i showed high diagnostic accuracy, with an ROC Area Under the Curve (AUC) of 0.936. A cut-off of 9.85 bacteria/μL achieved a sensitivity of 99.1% and specificity of 53.2%, allowing for the exclusion of 44.9% of samples with a negative predictive value of 99.7%. Performance was consistent across subgroups, including children and women. Conclusions: the Sysmex UF4000i flow cytometer provides a rapid and reliable method for UTI screening, potentially reducing the need for manual urine cultures and minimizing antibiotic overuse while maintaining accuracy.

Keywords

• Urinary Tract Infections (UTI)
• bacteriuria
• Sysmex UF4000i
• flow cytometry