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Performance of the cobas u 701 Analyzer in Urinary Tract Infection Screening

BACKGROUND: Negative urine cultures to rule out urinary tract infections (UTI) generate a considerable laboratory workload; thus, a rapid screening test is desirable. We evaluated the performance of a new automated microscopy analyzer, cobas u 701 (Roche Diagnostics International, Rotkreuz, Switzerl...

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Detalles Bibliográficos
Autores principales: Ortiz de la Tabla, Victoria, Gázquez, Gregoria, Infante, Ana, Martin, Coral, Buñuel, Fernando, Gutiérrez, Félix
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Korean Society for Laboratory Medicine 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6502947/
https://www.ncbi.nlm.nih.gov/pubmed/31037865
http://dx.doi.org/10.3343/alm.2019.39.5.464
Descripción
Sumario:BACKGROUND: Negative urine cultures to rule out urinary tract infections (UTI) generate a considerable laboratory workload; thus, a rapid screening test is desirable. We evaluated the performance of a new automated microscopy analyzer, cobas u 701 (Roche Diagnostics International, Rotkreuz, Switzerland) for the screening of UTI, and developed a rule-out strategy to reduce the number of samples requiring culture. We also assessed squamous epithelial cell (SEC) count as a predictor of culture contamination. METHODS: In total, 1,604 urine samples from outpatients were analyzed with cobas u 701 and culture. Bacterial (BAC) and white blood cell (WBC) counts were used for sample interpretation. To determine a useful cut-off point to predict negative cultures, we selected the highest sensitivity and specificity values obtained from ROC curves. Diagnostic accuracy by age and gender was evaluated. RESULTS: Urine culture showed growth of ≥10(4) colony forming units (CFU)/mL in 256 samples (16.0%). The highest sensitivity (91.8%) and specificity (68.4%) were obtained for cut-off points of 119 BAC/µL and 22 WBC/µL. The combination of BAC and WBC improved the performance of the rule-out strategy with a low rate of false-negative results (1.5%) and a high negative predictive value (NPV, 97.3%). Fifty-seven percent of the samples would not have required culture. SEC count was a poor predictor of culture contamination. CONCLUSIONS: cobas u 701 can substantially reduce the number of urine samples requiring culture, with a low false-negative rate and a high NPV.