Urine flow cytometry as a primary screening method to exclude urinary tract infections

Area of Science:

• Urology
• Clinical Diagnostics
• Microbiology

Background:

• Urine culture is the gold standard for diagnosing urinary tract infections (UTIs) but is time-consuming and expensive.
• Current dipstick urinalysis methods lack sufficient sensitivity and specificity for reliable UTI screening.
• Urine flow cytometry presents a promising alternative for rapid and accurate UTI assessment.

Purpose of the Study:

• To evaluate urine flow cytometry as a screening tool to exclude urinary tract infections.
• To determine an optimal cutoff value for flow cytometry to identify negative urine cultures.

Main Methods:

• A study included 281 outpatients from a urology department.
• Urine samples were analyzed using flow cytometry and compared against urine culture results.
• Receiver Operating Characteristic (ROC) analysis was employed to assess the diagnostic performance of flow cytometry and dipstick analysis.

Main Results:

• 18% of urine cultures were positive for UTIs (>10^4 CFU/mL).
• Flow cytometry demonstrated superior sensitivity and specificity compared to dipstick analysis for UTI exclusion.
• A cutoff of 60 bacteria/μL via flow cytometry yielded 100% sensitivity and 60% specificity, potentially eliminating 49% of cultures and preventing unnecessary antibiotic use in 20% of patients.

Conclusions:

• Urine flow cytometry is a reliable method for excluding urinary tract infections.
• A cutoff value of 60 bacteria/μL urine provides a 100% negative predictive value, with 0% false negatives.
• Implementing flow cytometry screening could significantly decrease the number of urine cultures performed and reduce unnecessary antibiotic prescriptions.