Intermittent bacteremia detected in an asymptomatic apheresis platelet donor with repeat positive culture for Escherichia coli: a case report.

Background: Bacterial culture of platelet concentrates (PCs) has been implemented to reduce the risk of infectious transfusion events. Most positive cultures are for skin flora or environmental organisms with no underlying pathology associated in the donor. Less frequently, enteric organisms have been isolated from PCs indicating asymptomatic donor bacteremia. We report a case of a donor with repeat positive culture for Escherichia coli.

Case Report: A 62-year-old single apheresis platelet (PLT) donor who passed all routine screening procedures had two intermittent positive BacT/ALERT cultures with E. coli. On both occasions, transfusion was prevented with the contaminated units. The donor denied any symptoms suggestive of infection and was referred to his family physician for evaluation. A barium enema revealed multiple colonic diverticula, although the donor has remained asymptomatic. Based on his history of repeat-positive cultures with the same enteric organism, the donor has been permanently deferred.

Discussion: PLT screening for bacterial contamination has been an effective measure to reduce the incidence of septic transfusion reactions. Important is the capture of Gram-negative bacteria, which can be involved in septic shock due to the production of endotoxins. In addition to the safety benefit to PLT recipients, PLT culture is valuable for blood donors. The recurrence of positive cultures with the same organism allows the identification of subclinical illnesses and, if appropriate, deferral from blood donation.

Conclusion: This asymptomatic donor has intermittent bacteremia likely related to diverticular disease. Isolation of E. coli twice prompted further investigation and donor deferral.