Retrograde transmission of Proteus mirabilis during platelet transfusion and the use of arbitrarily primed polymerase chain reaction for bacteria typing in suspected cases of transfusion transmission of infection.

BACKGROUND

When bacteria are found, after a platelet transfusion, in the recipient's blood as well as in the platelet concentrate (PC), a causal relationship is normally suspected, with the PC as the causative agent. The other alternative, that the patient has bacteremia and contaminated the PC, is less well documented in the literature.

CASE REPORT

Arbitrarily primed polymerase chain reaction (AP-PCR) was used for testing strains of Proteus mirabilis isolated from a patient's blood before and after a platelet transfusion and from the PC. Because of a febrile reaction after a platelet transfusion, bacterial culture was performed on the PC used, showing growth of P. mirabilis. The same species was found in the patient's blood after the transfusion. Posttransfusion sepsis caused by a contaminated PC was suspected, and anti-sepsis treatment was given to the recipient. Later, it became apparent that the patient had had bacteremia before the transfusion and that P. mirabilis was one of the species in the isolate. With AP-PCR, the identity of the three P. mirabilis isolates could be distinguished.

CONCLUSION

AP-PCR is a useful technique for distinguishing the identity of bacterial isolates from patients and blood components. A patient with bacteremia can contaminate a PC in conjunction with a platelet transfusion. With AP-PCR, the PC could be ruled out as the cause of the posttransfusion sepsis.