Listeria monocytogenes in donated platelets: a potential transfusion-transmitted pathogen intercepted through screening.

Background: Bacterial contamination of blood components is a potentially life-threatening complication of transfusions. In October 2005, the Centers for Disease Control and Prevention (CDC) noted four Listeria monocytogenes (Lm) isolates cultured from four different units of donated apheresis platelets (PLTs) among Lm isolates sent to the CDC National Listeria Reference Laboratory for subtyping as part of routine surveillance activities.

Study Design And Methods: We describe an investigation to determine possible common sources of infection among donors or factors associated with PLT collection or storage and to determine whether human transfusion-associated listeriosis cases had been reported. We also reviewed all isolates with PLTs as a source sent to the CDC National Listeria Reference Laboratory between November 1, 2005, and December 31, 2011.

Results: Each PLT donor-associated isolate had a distinct pulsed-field gel electrophoresis pattern combination. Other than these four cases, no other cases of Lm-contaminated PLTs were identified by the American Red Cross or by CDC during 2005. However, two additional cases of Lm isolated from donated PLTs were detected, one in 2008 and one in 2011.

Conclusion: Although the source of contamination for these PLT units is unclear, and a source common to all units was not identified, this investigation underscores the value of screening for bacterial contaminants of PLTs.