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The evaluation of microbial contamination in platelet concentrates prepared by two different methods
B Kocazeybek1, U Arabaci, H Akdur
1Department of Microbiology and Clinical Microbiology, University of Istanbul, Cerrahpaşa Medical Faculty, Turkey. bekirkcz@superonline.com
Abstract:
The microbial contamination of platelet concentrates (PCs) prepared by two different methods both with a high risk of bacterial contamination during preparation and storage were evaluated. For apheresis platelets, the concentrates were obtained using the Haemonetics MCS 3P device. For the random method, platelets were obtained by two phase centrifugation, in the Heraeus Cryofuge 8500 I device using the Kansuk 3-way bags which permit storage for five days. 1620 plateletpheresis units prepared by apheresis, and 9838 units prepared by the random method, were included in the study. Of the 11,458 PCs studied. 32 (0.27%) were false positives and 24 (0.2%) were real positives. All of the positive results occurred in platelets prepared by the random method. C. xerosis and S. epidermidis, S. hominis, Alpha-hemolytic streptococci, all flora of the skin, were isolated in the contaminated concentrates. The risk of microbial contamination of PCs, prepared both by apheresis and from whole blood, continues at a low rate although the products were collected into specific bags following rules including appropriate disinfection of the skin, correct centrifugation collection time and optimal storage conditions including temperature and agitation. These results again emphasize the importance of: obeying phlebotomy rules and hand disinfection of the person who collects the blood as well as the need for careful skin decontamination of the donor, during donation.
Insights
Microbial contamination in platelet concentrates (PCs) is low but occurs. Bacterial contamination was only found in randomly prepared platelets, emphasizing strict phlebotomy and disinfection protocols for safe blood products.
Area of Science:
- Transfusion Medicine
- Microbiology
- Blood Banking
Background:
- Microbial contamination of platelet concentrates (PCs) poses a significant risk to transfusion recipients.
- Evaluating contamination rates in PCs prepared by different methods is crucial for transfusion safety.
Purpose of the Study:
- To assess and compare the microbial contamination rates of platelet concentrates prepared via apheresis versus the random method.
- To identify the types of bacteria contaminating positive samples and determine their source.
Main Methods:
- Analysis of 1620 apheresis PCs (Haemonetics MCS 3P) and 9838 random-method PCs (Heraeus Cryofuge 8500 I).
- Microbial cultures were performed on all units to detect bacterial contamination.
- Identification of isolated bacterial species.
Main Results:
- Overall contamination rate was 0.47% (56/11,458), with 0.27% false positives and 0.2% true positives.
- All true positive results (24/11,458) occurred exclusively in platelet concentrates prepared by the random method.
- Common skin flora, including C. xerosis, S. epidermidis, S. hominis, and alpha-hemolytic streptococci, were identified in contaminated units.
Conclusions:
- The risk of microbial contamination in platelet concentrates remains low but is present.
- Platelet concentrates prepared by the random method showed a higher incidence of bacterial contamination compared to apheresis.
- Adherence to stringent phlebotomy rules, donor skin decontamination, and proper collection/storage procedures are critical for minimizing contamination risk.