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

E. Bongard, N. Frimodt-Møller, M. Gal, M. Wootton, R. Howe, N. Francis, H. Goossens, C. C. Butler

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 ≥10(5) 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.