(P-BC-12) Analysis of Confirmed Positive Bacterial Test Using the Large Volume Delayed Sampling at 48 Hours Testing Strategy for Platelets

Blood Services Group (BSG) performs routine culture-based bacterial testing using the BacT/ALERT 3D system (bioMeriéux) for all apheresis platelets (APLT) and buffy coat derived pooled platelets (PPLT) using the large volume delayed sampling at 48 hours post collection (LVDS ≥48 hrs) since August 2021. The LVDS ≥48 hrs testing strategy improves the sensitivity of the culture-based bacterial test and ensures the safety of platelet transfusion.


Study

Design/Methods:

Data  on the platelet type, the time to detection during incubation in the BacT/ALERT 3D system and the culture media type (aerobic/anaerobic) of the confirmed positive bacterial tests from August 2021 to April 2024 were compared to demonstrate if there is statistical significance between the variables.  


Results/Findings:

BSG tested 23,019 APLR and 40,941 PPLT during the study period. 7 APLR (0.01%) and 34 PPLT (0.05%) were confirmed positive for bacterial testing. 4 APLR (0.06%) were detected at Day 0 of incubation, 1 APLR (0.002%) at Day 3 and 2 APLR (0.003%) at Day 4. 5 PPLT (0.008%) were detected at Day 2, 13 PPLT (0.02%) at Day 3, 13 PPLT (0.02%) at Day 4 and 3 PPLT (0.005%) at Day 5. Detection by the BacT/ALERT 3D systemfor APLR units were earlier compared to PPLT (X²=22.199, df=5, p=.05).

Out of the 41 total cases, 4 units (0.006%) were positive for bacterial growth for both culture media types at Day 0. For the remaining 37 cases, only the anaerobic bottle was positive for bacterial growth and the time to detection range from Day 2 to Day 5 of incubation, with most units being detected on Day 3 and Day 4 of incubation (29/41, 0.045%) . Positive aerobic culture media are detected within 24 hrs of incubation whereas anaerobic culture media may be detected until the last day of incubation (X²=41.000, df=5, p=.05).


Conclusions:

Significant difference between the variables suggests the possible elimination of the anaerobic bottle and to reduce the incubation period.  Furthermore, Cutibacterium acnes, which is considered clinically insignificant, is the most commonly identified microorganism in the study (Table 1).  However, there are documented cases of C. acnes infections with significant morbidity in post-operative individuals.  Therefore, It is prudent to continue exercising the testing strategy to eliminate any possibility of transfusion related infections.