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Analytic laboratory performance of a point of care urine culture kit for diagnosis and antibiotic susceptibility testing

Abstract

Currently available point-of-care (POC) diagnostic tests for managing urinary tract infections (UTIs) in general practice are limited by poor performance characteristics, and laboratory culture generally provides results only after a few days. This laboratory evaluation compared the analytic performance of the POC UK Flexicult™ (Statens Serum Institut) (SSI) urinary kit for quantification, identification and antibiotic susceptibility testing and routine UK National Health Service (NHS) urine processing to an advanced urine culture method. Two hundred urine samples routinely submitted to the Public Health Wales Microbiology Laboratory were divided and: (1) analysed by routine NHS microbiological tests as per local laboratory standard operating procedures, (2) inoculated onto the UK Flexicult™ SSI urinary kit and (3) spiral plated onto Colorex Orientation UTI medium (E&O Laboratories Ltd). The results were evaluated between the NHS and Flexicult™ methods, and discordant results were compared to the spiral plating method. The UK Flexicult™ SSI urinary kit was compared to routine NHS culture for identification of a pure or predominant uropathogen at ≥105 cfu/mL, with a positive discordancy rate of 13.5 % and a negative discordancy rate of 3 %. The sensitivity and specificity were 86.7 % [95 % confidence interval (CI) 73.8–93.7] and 82.6 % (95 % CI 75.8–87.7), respectively. The UK Flexicult™ SSI urinary kit was comparable to routine NHS urine processing in identifying microbiologically positive UTIs in this laboratory evaluation. However, the number of false-positive samples could lead to over-prescribing of antibiotics in clinical practice. The Flexicult™ SSI kit could be useful as a POC test for UTIs in primary care but further pragmatic evaluations are necessary.

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Acknowledgements

The authors would like to acknowledge the funders of this study: the Medical Research Council and Cardiff University for funding the corresponding author’s PhD. The authors would also like to acknowledge that the research leading to these results is associated with funding received from the European Community’s Seventh Framework Programme FP7/2007–2013 under grant agreement no. 282512 and the R-GNOSIS consortium. Acknowledgement also goes to the contribution of staff from the Specialist Antimicrobial Chemotherapy Unit and Public Health Wales Microbiology Laboratory, University Hospital Wales.

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The authors declare that they have no conflict of interest.

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Correspondence to E. Bongard.

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Bongard, E., Frimodt-Møller, N., Gal, M. et al. Analytic laboratory performance of a point of care urine culture kit for diagnosis and antibiotic susceptibility testing. Eur J Clin Microbiol Infect Dis 34, 2111–2119 (2015). https://doi.org/10.1007/s10096-015-2460-4

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Keywords

  • National Health Service
  • Resistance Rate
  • Nitrofurantoin
  • Cephalothin
  • Clinical Microbiology Laboratory