<scp><i>Listeria monocytogenes</i></scp> 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 O ctober 2005, the C enters for D isease C ontrol and P revention ( CDC ) noted four L isteria monocytogenes ( Lm ) isolates cultured from four different units of donated apheresis platelets ( PLT s) 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 PLT s as a source sent to the CDC N ational L isteria R eference L aboratory between N ovember 1, 2005, and D ecember 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 PLT s 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 PLT s.