Usefulness of UF-5000 automatic screening system in UTI diagnosis

We have evaluated the Sysmex UF-5000 cytometer use in microbiology for the screening of negative urines, looking for cut-off points to detect bacteria and leukocytes. The number of processed urines was 3569, the highest to date in these studies. The best general cut-off point has been 100 bact/& mu;l, giving an area under the ROC curve of 0.868, a sensitivity of 96%, a specificity of 50%, 1.17% of false negatives, and saving 40% of cultures. The PPV and NPV have been 35.5 and 95.4 respectively. The leukocyte count has not been useful. Finally, we have evaluated urine screening usefulness, concluding that in laboratories such as ours (284 urines/working day) or smaller, it is not cost-effective.

Automated summary

We evaluated the use of Sysmex UF-5000 cytometer in microbiology for screening negative urine samples, determining the cutoff points for detecting bacteria and leukocytes. Our study included the analysis of 3569 urine samples, the highest number to date in similar studies. The optimal cutoff point for detecting bacteria was found to be 100 bact/μl, with an area under the ROC curve of 0.868, a sensitivity of 96%, a specificity of 50%, a false negative rate of 1.17%, and a 40% reduction in culture usage. The positive predictive value and negative predictive value were 35.5 and 95.4, respectively. The leukocyte count was not found to be useful. Finally, we concluded that urine screening is not cost-effective in laboratories with similar or smaller sample volumes (284 urines/working day).