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Evaluation of the IRIS 939 UDx flow microscope as a screening system for urinary tract infection
  1. C Hughes,
  2. M J Roebuck
  1. Department of Medical Microbiology, Rotherham General Hospitals NHS Trust, Rotherham S60 2UD, UK
  1. Correspondence to:
 Mr Christopher Hughes
 Medical Microbiology, Rotherham General Hospital, Rotherham S60 2UD, UK;


Aims: To evaluate the IRIS flow microscope for the examination of urine specimens and to compare its performance with that of manual methods; in addition, to assess its usefulness as a screening system for the detection of significant bacteriuria in a routine clinical laboratory.

Methods: The IRIS system was compared with manual quantitative microscopy for the detection of formed elements and with a variety of culture methods to detect urinary tract infection.

Results: The IRIS had a higher sensitivity for the detection of clinically significant formed elements than did manual methods, and using a combination of bacterial and white cell counts produced a sensitivity and specificity of 94.9% and 54.4%, respectively, for predicting positive significant growth, with a 98.5% predictive value for a negative result. Approximately 50% of specimens could be reported as negative on the day of receipt using the screening algorithm.

Conclusions: The sensitivity and specificity of the IRIS is equivalent to that of other automated screening systems and would remove the need for manual microscopy for most specimens. The system was easy to operate and is a useful addition to the methods currently available for the examination of urine specimens.

  • bacteriuria
  • automation
  • flow microscopy
  • BACT, bacteria
  • cfu, colony forming units
  • RBC, erythrocytes
  • SEC, squamous epithelial cells
  • UTI, urinary tract infection
  • WBC, leucocytes

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