Evaluation of bacterial contamination of platelet concentrates collected at Tehran Regional Blood Center

Background and objectivesIn spite of major advances in the field of quality assurance in the process of collection, preparation and storage of platelets, bacterial infection following platelet transfusion remains a major problem in transfusion medicine. The present study was carried out in order to evaluate bacterial contamination of platelet concentrates collected at Tehran Regional Educational Blood Transfusion Center. Materials and MethodsBacterial growth of samples of platelet concentrates was studied in blood agar, EMB and thioglycollate broth after 48 hours at 37oC. The use of differentiation tests was made when any bacterial growth was observed. Simultaneously, the samples were also cultured in thioglycollate broth and studied for any turbidity or color change within 7 days. Any changes made the samples to be cultured in blood agar and EMB. Finally, the contamination rate and the ratio of contaminating bacteria were determined. Out of 7700 samples, three fourth (5775 samples) were taken from the cord and one fourth (1925) from both the bag and the cord. ResultsOut of 7700 samples of platelet concentrates studied, 14 (0.18%) were found positive for bacterial contamination. The contamination rate was estimated to be one in every 550 tested platelets (0.18%). Since in cases of blood bag contamination, the cord had been contaminated as well, there was then no difference on whether the sample was taken from the bag or cord. The bacteria identified were as follows: Staph. epidermidis (n=4), Staph. saprophyticus (n=2), Acinetobacter (n=5), Bacillus sp. (n=3). ConclusionsThe results show that screening platelet concentrates for bacterial contamination is necessary for blood transfusion centers and hospital blood banks.