659 - Evaluation of Four Chromogenic Agars for Urine Culture Including Time and Cost Savings Analysis

Background: With a volume of approximately 5000 urine culture specimens per month in our tertiary-care university center hospital’s microbiology laboratory, we wanted to evaluate methods aiming to improve workflow and performance while reducing turnaround time and potentially overall cost.

Methods: 310 urine culture specimens as well as selected less frequent pathogens (A. urinae - 26 strains, C. urealyticum - 4 strains) were plated on four chromogenic agars in parallel with standard protocol MacConkey (MAC) and blood agar (BA). Chromogenic agars evaluated were: UriSelect^TM 4 (Bio-Rad), CHROMID® CPS® Elite (bioMérieux), Brillance^TM UTI Clarity^TM agar Biplate  (Oxoid) and BD^TM CHROMagar^TM Orientation (BD). Primary outcome was overall growth performance for frequent pathogens and for gram positives, where chromogenic agars were previously reported to underperform.The number of additional tests needed and the appreciation of different media by laboratory personnel were also assessed. A sub-analysis measured the total time required to plate and to read 50 consecutive specimens comparatively for the 4 chromogenic agars and for MAC/BA.
 

Results: Global performance was 90% for Uriselect, 88% for ChromID, 89% for Chromagar and 81% for Brillance compared to 84% for standard method. ChromID and Brillance supported the growth of more A. urinae and C. urealyticum than the other 2 chromogenic agars. All monoplate chromogenic agars were appreciated equally by technologists.  In addition, for all chromogenic agars, working time was reduced by half as compared to MAC/BA. We estimated a time economy of approximately 80 hours per month in our laboratory, translating in a net annual economy.

Conclusion: All 4 chromogenic medias evaluated in our study had an acceptable performance, with specific strengths and weaknesses for each one. The choice of ChromID CPS Elite (bioMérieux) for our center was based on pre-established criteria including performance for more fastidious gram positives, best time and cost economy, and compatibility with current identification method and susceptibility testing platform.  However, since the 4 chromogenic agars have been adequately verified in our laboratory, we consider that they could be interchangeable if needed.