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Possible implication of sterile connecting device in contamination of pooled platelet concentrates
G Mertens1, L Muylle, H Goossens
1Antwerp Blood Transfusion Center, Belgian Red Cross, Edegem, Belgium.
Abstract:
Considering the possibility that a pooled random donor platelet concentrate could become contaminated by welding with a sterile connecting device, we undertook a study to determine the influence of pooling on the contamination rate. As a control group, apheresis platelets were examined. Bacteriological testing was done with a sensitive CO2 detecting culture system, the BacT/ Alert. Out of 1105 pooled platelet concentrates prepared by the buffy coat method, 15 (1.4%) were confirmed as contaminated, all with Staphylococcus epidermidis and two with a second bacterial species, i.e. Staphylococcus capitis and Propionibacterium acnes, respectively. Median detection time by the BacT/Alert was 23 h. Twelve pools of five units were contaminated, which is significantly more than the three contaminated pools of four units. On the other hand, the reuse of the welding wafers proved not be a risk factor for contamination. One welded tubing segment of a contaminated platelet concentrate failed the air leakage test, an incident which was 73 times more frequent than with the sterile platelet concentrates. We found five pooled platelet concentrates containing Staphylococci from which no bacteria could be grown from the individual buffy coats that had been pooled. We suggest the contamination here to have occurred after separation of the buffy coat from the whole blood, possibly during the welding process. Finally, none out of 378 apheresis platelet concentrates was contaminated. All our observations highlight the potential risk for contamination when making pooled platelet concentrates with a sterile connecting device. For this type of transfusion product, we advocate bacteriological screening of all units before release. The incubation time for the sterility test should, however, be limited to 36 h, if logistical problems with the availability of platelets are to be avoided.
Insights
Pooling random donor platelets increases bacterial contamination risk, particularly with sterile connecting devices. Apheresis platelets showed no contamination, highlighting the need for screening pooled products.
Area of Science:
- Transfusion Medicine
- Microbiology
- Blood Banking
Background:
- Pooled platelet concentrates are used to increase platelet availability.
- Sterile connecting devices are employed in preparing pooled platelets.
- Potential for bacterial contamination during pooling exists.
Purpose of the Study:
- To investigate the influence of pooling on bacterial contamination rates.
- To compare contamination rates between pooled and apheresis platelets.
- To identify potential sources of contamination in pooled platelet concentrates.
Main Methods:
- Bacteriological testing of 1105 pooled platelet concentrates and 378 apheresis platelets.
- Utilized the CO2-detecting culture system, BacT/Alert, for sensitive detection.
- Examined pooled units prepared by the buffy coat method and apheresis platelets.
Main Results:
- 1.4% (15/1105) of pooled platelet concentrates were contaminated, primarily with Staphylococcus epidermidis.
- Contamination was significantly higher in pools of five units compared to pools of four units.
- No contamination was found in 378 apheresis platelet concentrates; welded tubing segments showed increased leakage in contaminated pools.
Conclusions:
- Pooling random donor platelets with sterile connecting devices poses a significant risk of bacterial contamination.
- Contamination likely occurs post-buffy coat separation, possibly during the welding process.
- Bacteriological screening of all pooled platelet units before release is recommended, with a 36-hour incubation limit to balance safety and availability.