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Keywords:

  • bacteriuria;
  • cytometry;
  • Sysmex;
  • urinary tract infection;
  • urine

Abstract

Objective

To evaluate the performance of the Sysmex UF1000i automatic urine screening system in the quantitative culture of fast-growth aerobic/facultative bacteria.

Methods and Results

A standard procedure was used to recover fast-growth aerobic/facultative micro-organisms in 1225 samples, applying (Sysmex®) flow cytometry for parallel bacteria and leucocyte counts. According to the area under the receiver operating characteristic curve, the optimal cut-off values to detect bacteriuria >105 colony forming units (CFU) ml−1 were 690/μl for bacteria and 38/μl for leucocytes (sensitivity, 92%; specificity, 65%; positive predictive value [PPV], 39%; and negative predictive value [NPV], 97%). The use of a single cut-off point of 150 bacteria μl−1 to detect significant bacteriuria of >105 CFU ml−1 or of ≥104 CFU ml−1 plus leucocyturia obtained similar results (sensitivity, 89%; specificity, 54%; PPV, 31%; and NPV, 96%) and allowed 45·7% of the samples to be rapidly excluded.

Conclusions

The Sysmex UF1000i system can be adapted for bacteriuria screening by the use of an appropriate cut-off point.

Significance and Impact of the Study

This screening system significantly reduces the workload and produces very few false positives and negatives.