Fatal false-negative transfusion infection involving a buffy coat platelet pool contaminated with biofilm-positive Staphylococcus epidermidis: a case report.

BACKGROUND: Bacterial contamination of platelet concentrates (PCs) poses the major posttransfusion infectious risk in developed countries. The aerobic microorganism most frequently isolated from PCs is coagulase-negative Staphylococcus epidermidis, a normal inhabitant of the human skin, which has been involved in fatal transfusion reactions worldwide., CASE REPORT: In September 2014, a splenectomized elderly male patient, suffering from leukemia, was transfused with two 5-day-old buffy coat platelet (PLT) pools. The patient returned to emergency on the same day with a low-grade fever. He was bacteremic and died on the next day. Microbiology and molecular testing of a blood sample from the patient and one of the PCs yielded the same S. epidermidis strain. Further analysis demonstrated that this S. epidermidis isolate displays a biofilm-positive phenotype in PCs., DISCUSSION: At Canadian Blood Services, PCs are screened for bacterial contamination with the BacT/ALERT system (bioMerieux) at approximately 24 hours postcollection. The implicated PC had been tested and yielded a false-negative culture result. A titration experiment indicated that, at the time of screening, the contaminated PC had a titer of less than 0.74 colony-forming units (CFU)/mL (