Evaluation of a rapid, direct sample loading electrochemical AST assay with clinical urine samples.

INTRODUCTION: Phenotypic antibiotic susceptibility testing (AST) is essential, but conventional culture-based methods require 48-72 h, delaying targeted treatment. Here we report a first small study of a direct electrochemical AST system on clinical urine samples. The study aimed to validate the technology and support further research. METHODS: 18 urine and 2 control samples were tested with 3 antibiotics above and below EUCAST breakpoints, resulting in 474 antibiotic-sample combinations grouped as 158 triplets. RESULTS: Using routine clinical diagnostics as reference method, categorical agreement, sensitivity, and specificity were 87.9% (95% CI, 83.7-91.1%), 0.95 (95% CI, 0.8952-0.9769) and 0.831 (95% CI, 0.7684-0.8786), respectively. The average time to result was 6.0 ± 3.3 h. Its non-species-specific electrochemical principle theoretically allows it to be applied to various sample types and organisms. DISCUSSION: These results demonstrate that the electrochemical AST platform provides accurate results on the same day directly from patient samples, likely eliminating the need for mandatory pre-culturing.