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Bacterial contamination of platelet concentrates produced in New Zealand
Michelle Dickson1, Dorothy Dinesh
1New Zealand Blood Service, Private Bag 7904, Wellington 6242, New Zealand.
Aims:
To identify the rate of bacterial contamination of platelet concentrates in New Zealand and compare with other countries who use the BacT/ALERT screening system. To report on septic transfusion reactions associated with platelet transfusion in New Zealand.
Methods:
Six mL of platelet concentrate is inoculated into a BacT/ALERT BPA (aerobic culture) bottle on Day 2 post-collection. Bottles that are flagged as positive are sent to the microbiology laboratory, with the associated unit, for confirmatory testing. Platelet units that have expired are sampled again. Results from the four blood processing sites in New Zealand were reviewed.
Results:
59,461 (65%) platelet components were sampled on Day 2 and 15,560 (17%) were re-sampled post-expiry, between December 2003 and September 2011. The rate of confirmed bacterial contamination was 0.04% for Day 2 sampling and 0.04% for post-expiry sampling. The rate in the published literature ranges from 0.01-0.74% and is lower (0.01-0.18%) when diversion of the initial flow of blood is utilised. There were five bacterial transfusion transmitted infections associated with platelet transfusion reported during the study period.
Conclusions:
BacT/ALERT screening reduces the transfusion of bacterially contaminated platelet concentrates. Day 2 sampling does not identify all contaminated units.
Insights
Bacterial contamination in platelet concentrates was low (0.04%) in New Zealand using the BacT/ALERT system. While this screening method reduces bacterial transfusion risks, Day 2 sampling misses some contaminated units.
Area of Science:
- Transfusion Medicine
- Microbiology
- Public Health
Background:
- Bacterial contamination of platelet concentrates poses a significant risk of transfusion-transmitted bacterial infections.
- The BacT/ALERT system is widely used for screening blood products for bacterial contamination.
Purpose of the Study:
- To determine the rate of bacterial contamination in platelet concentrates in New Zealand.
- To compare these rates with international data from facilities using the BacT/ALERT system.
- To report on septic transfusion reactions linked to platelet transfusions in New Zealand.
Main Methods:
- Platelet concentrates were sampled on Day 2 post-collection and again post-expiry.
- Samples were inoculated into BacT/ALERT BPA aerobic culture bottles.
- Positive results were confirmed through microbiological testing.
Main Results:
- Between 2003 and 2011, 59,461 units were sampled on Day 2, with a contamination rate of 0.04%.
- 15,560 units were re-sampled post-expiry, also showing a 0.04% contamination rate.
- Five bacterial transfusion-transmitted infections associated with platelet transfusions were reported during the study period.
Conclusions:
- The BacT/ALERT screening system effectively reduces the transfusion of bacterially contaminated platelet concentrates.
- Sampling on Day 2 post-collection is insufficient to detect all contaminated units.
