Evaluation of automated streaking patterns in urine culture for clinical workflow optimization

Automated streaking systems improve the standardization of microbiological workflows; however, the optimal streaking pattern for single-colony isolation remains uncertain. Seven preinstalled streaking patterns were systematically evaluated using the Copan WASP system to identify the most effective pattern for urine culture. We assessed seven pre-installed streaking patterns using five standard bacterial strains at varying bacterial loads from 10² to10⁷ CFU/mL. The top three patterns were further tested on clinical urine samples collected over three months. Single-colony isolation efficiencies were compared across different bacterial loads and polymicrobial samples. Among standard strains, Single Streak Type 6 (SST6) exhibited the highest single-colony isolation efficiency, followed by Four Quadrants Streak Type 5 and Five Quadrants Streak Type 1. SST6 consistently performed the best under moderate bacterial loads (10-10 CFU/mL). However, in high bacterial load samples (≥ 10⁷ CFU/mL), Four Quadrants Streak Type 5 outperformed SST6 (p = 0.003). Additionally, SST6 failed to isolate single colonies of the five species in the polymicrobial samples. Five Quadrants Streak Type 1 showed the lowest coefficient of variation, suggesting greater consistency across different bacterial loads. This study highlighted the critical role of streaking pattern selection in automated streaking systems. While the performance varied depending on the bacterial load and sample complexity, certain patterns demonstrated superior single-colony isolation and consistency. Optimizing streaking patterns is essential for improving reproducibility, enhancing diagnostic accuracy, and standardizing automated microbiological workflows.