Importance of Selecting the Proper Urine Cultures Protocol: Our WASPImportance of Selecting the Proper Urine Cultures Protocol: Our WASP™ Automation Experience in Microbiology Automation Experience in Microbiology
The Copan Walk Away Specimen Processor (WASP™) is an instrument for automated plating of microbiological specimens. The WASP™ (Copan Italia, Brescia, Italy) system includes software that allows selection of various inoculation protocols and streaking patterns. The WASP™ was acquired by our laboratory to facilitate the daily large number of specimen’s inoculation and plating.
The objectives of this study were to assess:
1.Urine specimens processing performance quality in terms of inoculation loop/volume, streaking pattern, colonies separation or overgrowth.
2.Improvement of laboratory workflow and quality performance in results reporting.
METHODS: This study included 7,000 urine specimens, all collected in UriSwab™ (Copan). Initially 250 samples were tested in duplicate. The WASP™ samples, inoculated with 1 and 10 microliters loops with the streaking pattern “Single streak type 2,” were compared to the current manual method according to laboratory SOPs using 1 and 10 microliters loops. After the evaluation of both WASP™ and manually streaking the results were compared and was noted that cultures plated by the WASP™ were easier to read with more single colonies. From that point all the urines specimens were loaded on the WASP™ and processed using the validated predefined protocol: 1 microliter loop, streaking pattern Single streak type 2, on Columbia Blood Agar with 5% sheep blood and Mac Conkey Agar (OXOID), and incubated overnight at 35°C ± 2 until adequate growth was present.
RESULTS: The data from the 250 samples tested in duplicate (manual 1 and 10 microliter loops and WASP 1 and 10 microliter loops), made us decide to use the 1 microliter loop, streaking pattern Single streak type 2. Using the WASP™ 1 microliter loop for urine culture plating, we obtained 100% isolated colonies compared with 85% with 10 microliter loop. The percentage obtained with manual method was 95% using 1 microliter loop and 83% with 10 microliter loop. In the 7,000 urine samples tested on the WASP™ 4,203 (60.04%) were negative and 2,530 (36.14%) were found positive. In the positive urine culture 97% had only one pathogen while 3% had mixed pathogens. A more accurate streaking was observed with the WASP™ method for mixed cultures with 3 or more pathogens (3.82%). Not a single urine sample had to be repeated due to the overgrowth.
CONCLUSIONS: All urine specimens, collected and transported in UriSwab™, were processed on the WASP™ using 1 microliter loop and Single streak type 2 pattern. Since the introduction of the WASP™ we noted an increased number of isolated colonies using the 1 microliter loop. Result turnaround time and easy reading of isolated colonies improved the urine cultures workup, significantly reduced the handling time for urine specimen processing and facilitated the laboratory workflow.