Lactococcus lactis blood products contamination resulting in fatal human case: insights from a forensic case

Lactococcus species are micro-aerophilic Gram positive bacteria characterized by low virulence features and other biotechnological properties of industrial interest. They are thus widely employed in food fermentation processes. Despite its low pathogenic potential and food grade safety, L. lactis may, however, rarely cause infections, especially among immunocompromised hosts. Moreover, the growing complexity of patients implies increased detections of such infections. This said, there is a paucity of data concerning L. lactis infections from infusion of blood transfusion products. To our knowledge, this is the first case of L. lactis infection from transfusion of blood products, as observed in an 82-year-old Caucasian male undergoing weekly platelet and blood transfusion due to sustained severe thrombocytopenia. Albeit minimally pathogenic, L. lactis should be considered for thorough testing, especially in the case of human-derived infusion products such as platelets due to their storage requirements for extended times at room temperature and their use in immunocompromised and critically ill subjects.