Evaluation of the Cobas u 701 microscopy analyser compared with urine culture in screening for urinary tract infection

Abstract

Purpose. A new automated Cobas u 701 microscopy analyser for urine sediment examination was introduced. The aim of this study was to evaluate the analyser in comparison with urine culture in screening for urinary tract infection (UTI).Methodology. A total of 852 urine specimens submitted for culture were included in this study. Urine sediment examination was performed using the Cobas u 701 microscopy analyser. The results of the bacteria (BAC) and yeast (YEA) analyses were compared with the results from urine culture as a method for UTI screening. In addition, we compared the BAC results with white blood cells (WBCs) and leukocyte and nitrite measurement in the Cobas u 601 system.Results. Of the 852 urine specimens, 16.1 % (N=137) were positive by urine culture, yielding 130 bacteria from 124 specimens and 14 yeasts from 14 specimens. The Cobas u 701 microscopy analyser provided no result for 52 specimens because of their high turbidity. The sensitivity, specificity, positive predictive value and negative predictive value were 85.8, 69.4, 33.1 and 96.5 %, respectively. For YEA, these figures were 100, 91.9, 15.8 and 100 %, respectively. The areas under the curve for BAC and WBCs were 0.827 [95 % confidence interval (CI) 0.799, 0.852] and 0.727 (95 % CI 0.695, 0.757), respectively. The sensitivity of the leukocyte and nitrite was 63.5 and 54.6 %, respectively.Conclusion. The Cobas u 701 microscopy analyser showed good diagnostic performance. It can be used for rapid screening for UTI and can reduce the number of cultures required.