P32 Performance of a novel molecular test designed for point-of-care UTI diagnosis

Abstract

Abstract Objectives To evaluate the performance of a novel LAMP-based molecular test for the diagnosis of UTIs. The Llusern Scientific UTI test system consists of a panel of six uropathogen tests, positive and negative controls and an analyser, ‘Lodestar DX’ (Figure 1). The analyser will read the reaction data and give the user a simple ‘positive’ or ‘negative’ read out for each uropathogen. The specific aim was to determine the sensitivity and specificity of the test system for the most common uropathogen, Escherichia coli. Figure 1.Lodestar DX. Methods In total, 149 urine samples received by Public Health Wales laboratories, Cardiff were randomly selected; 1 μL of each urine sample was added directly to each pre-made E. coli LAMP test. E. coli LAMP tests were placed into the Lodestar DX analyser and run. Results were shown and recorded after 40 minutes as ‘positive’ or ‘negative’ according to the decision of Lodestar's algorithm. LAMP results were compared to standard culture results and sensitivity and specificity calculated. Results Overall sensitivity of the E. coli LAMP test was 86.2%. Specificity was 88.3% (Table 1). Of the 14 samples positive in the LAMP test for E. coli but not recorded as E. coli using culture, 11 were from ‘mixed growth’ samples (Table 2). Table 1.Sensitivity and specificity of E. coli LAMP testLAMP positiveLAMP negativeTotalCulture positive25 (true positives)4 (false negatives)29Culture negative14 (false positives)106 (true negatives)120Total39110149Overall sensitivity((25/29) × 100) = 86.2%Overall specificity((106/120) × 100) = 88.3% Table 2.Results of LAMP compared with culture resultsCulture resultnE. coli Lodestar LAMP resultpositiveinconclusivenegativeE. coli positive292504Other pathogen positive121011Mixed growth6111050No growth472045Total149390110 Conclusions The Llusern Scientific UTI test system shows great promise as a point-of-care diagnostic tool. Sensitivity and specificity for E. coli was high and the test system may be better at diagnosing mixed infections which represent a high proportion of all culture results. The test system is easy to use with no sample processing and minimal training requirements. Test results are available in 40 min, compared to 24–72 h for culture results. The performance of the test system for the detection of other uropathogens (Klebsiella, Enterococcus, Pseudomonas, Proteus and S. saprophyticus) is ongoing. Sensitivity can be further improved by refining the test method.