Transfusion-Transmitted Listeria Infection Reported in Italy

Investigators in Italy have reported a rare case of Listeria monocytogenes infection in a 78-year-old woman with liver cancer who received a transfusion of pooled platelet concentrate containing a closely related strain. They published their findings this week in the journal Emerging Infectious Diseases.

L. monocytogenes is a gram-positive, primarily foodborne pathogen responsible for severe invasive infections, particularly in immunocompromised patients. A previous case of transfusion-transmitted Listeria infection has been documented in the literature. Additionally, the authors cited two case reports of platelet products contaminated with Listeria that were intercepted before transfusion.

The patient presented to an Italian emergency department in June 2022 with persistent fever, nausea and vomiting. Hematological tests revealed severe pancytopenia, likely due to chemotherapy. The medical team administered granulocyte growth factor, transfusion with concentrated red blood cells and empirical antibiotic therapy.

The day following presentation, she received a pool of five buffy platelets. After receiving approximately 150 milliliters of the product, she developed chills, nausea and fever. The transfusion was stopped and the patient received hydrocortisone for clinical suspicion of a transfusion reaction. L. monocytogenes was identified 25 hours after collection of a second blood culture. The patient received 21 days of active antibiotics and recovered.

Each of the five donated platelet units for bacterial contamination using the BacT/Alert 3D system (bioMérieux) and detected L. monocytogenes in a single unit. Although the donor was investigated for risk factors related to listerosis, none were identified and repeat donor blood cultures were negative. Genetic testing confirmed that L. monocytogenes isolates recovered from the transfused patient's blood cultures, the platelet concentrate and the blood donor's platelet unit were closely related.

The source of the donor’s bacteremia remains unclear, but the authors propose two explanations. The most likely explanation is that the donor experienced transient bacteremia and was asymptomatic at the time of donation. Environmental contamination was also considered.

The authors also noted that questionnaires administered to assess blood donors' health and medical history may not be useful in identifying L. monocytogenes infection because healthy persons are generally asymptomatic carriers. To enhance safety in transfusion medicine, they recommend implementing surveillance activities and additional measures such as secondary testing and pathogen-reduction technology.

Additional information about L. monocytogenes and blood products is available in AABB’s Listeria monocytogenes fact sheet.