1. Cutoff values for bacteria and leukocytes for urine flow cytometer Sysmex UF-1000i in urinary tract infections
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Manoni, Fabio, Fornasiero, Lucia, Ercolin, Mauro, Tinello, Agostino, Ferrian, Melissa, Hoffer, Paolo, Valverde, Sara, and Gessoni, Gianluca
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DIAGNOSTIC reagents & test kits , *DIAGNOSTIC microbiology , *URINARY tract infection diagnosis , *MEDICAL quality control , *BACTERIAL cultures , *ELECTROLYTES , *URINALYSIS , *BACTERIURIA , *URINE microbiology , *LEUCOCYTES - Abstract
Abstract: Because urinary tract infections (UTIs) are a quite common disease, the gold standard for diagnosing UTIs is still bacterial culture, although a large percentage of samples are negative: unnecessary cultures can be reduced by means of an effective screening test. The analytic performance of a new urine cytometer, the UF-1000i, has been tested on 1463 urine samples submitted to our laboratory for culture. Bacteria and leukocyte counts have been compared by means of the UF-1000i with colony-forming unit (CFU) quantification on citrate lactose electrolytes deficient agar to assess the best cutoff values. By using quantitative cultures and considering as positive a sample with 10 × 105 CFU/mL, 546 positive samples (37%) were observed. If compared with 10 × 105 CFU/mL, the cutoff values obtained were 125 bacteria/μL and 40 leukocytes/ μL, respectively. Analytic parameters such as sensitivity, specificity, positive predictive value, negative predictive value, and correctly classified incidence were satisfactory. Based on the results obtained in this study, when using the UF-1000i analyzer for a screening test for UTI, a cutoff value of 40 white blood cells/μL should be adopted. The cutoff value for bacteria should be 125/μL for those clinical conditions in which 10 × 105 CFU/mL indicates a positivity. [Copyright &y& Elsevier]
- Published
- 2009
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