Combination of quantitative bacterial and WBC count from urine flow cytometry to estimate the success of urine culture in symptomatic urinary tract infections

Abstract

Aims: Urinary tract infection (UTI) is a common infection that can occur in inpatient and outpatient setting. The current guideline is using urine culture as standard for UTI diagnosis. Recently, urine flow cytometry method with dedicated bacterial channel is intended as useful tools for UTI diagnostic. In our study, we determine the cut-off value of white blood cell (WBC) and bacterial count of fluorescence flow cytometry as an estimation of the successful of urine culture in symptomatic UTI population. Methodology and results: The study was held from January until April 2015 at secondary and tertiary hospital in Bandung, Indonesia. A number of 215 UTI patients were enrolled. Urine specimens were analyzed using automated flow cytometry urine analyzer (UX2000, Sysmex Corp., Japan) and results were compared with urine culture, as gold standard. The cut-off value of WBC and bacterial count were determined using ROC to generate the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The combination of bacterial count ≥ 277.4 bacteria/uL, WBC count ≥ 300.7 cells/uL, in symptomatic UTI patients, achieved sensitivity of 82.7%, specificity of 87.5%, PPV of 96.6% and NPV of 53.8%. This combination can be use as estimation of positive culture as high as 96.6%. Conclusion, significance and impact of study: In microbiology aspect, quantitative bacterial count and WBC count of urine flow cytometry can be useful to estimate the success of culture-proven UTI, which can help in clinician decisionmaking and better patient management.