Clinical evaluation of the APAS® Independence: Automated imaging and interpretation of urine cultures using artificial intelligence with composite reference standard discrepant resolution

Background: This study reports the outcome of the first evaluation of the APAS (R) Independence for automated reading and preliminary interpretation of urine cultures in the routine clinical microbiology laboratory. In a 2-stage evaluation involving 3000 urine samples, two objectives were assessed; 1) the sensitivity and specificity of the APAS (R) Independence compared to microbiologists using colony enumeration as the primary determinant, and 2) the variability between microbiologists in enumerating bacterial cultures using traditional culture reading techniques, performed independently to APAS (R) Independence interpretation. Methods: Routine urine samples received into the laboratory were processed and culture plates were interpreted by standard methodology and with the APAS (R) Independence. Results were compared using typical discrepant result resolution and with a composite reference standard, which provided an alternative assessment of performance. Results: The significant growth sensitivity of the APAS (R) Independence was determined to be 0.919 with a 95% confidence interval of (0.879, 0.948), and the growth specificity was 0.877 with a 95% confidence interval of (0.827, 0.916). Variability between microbiologists was demonstrated with microbiologist bi-plate enumerations in agreement with the consensus 88.6% of the time. Conclusion: The APAS (R) Independence appears to offer microbiology laboratories a mechanism to standardise the processing and assessment of urine cultures whilst augmenting the skills of specialist microbiology staff.