Medical Laboratory Scientist (MLS) ASCP Practice Exam

Yersinia enterocolitica is primarily associated with septic reactions during Red Blood Cell transfusions due to its ability to survive in cold temperatures and its potential to contaminate stored blood products. This organism is commonly found in animal reservoirs and can cause transfusion-related septicemia when blood units are contaminated.

The risk is particularly significant because Yersinia enterocolitica can grow in refrigerated conditions, making it a unique threat during blood storage and transfusion practices. The organism has virulence factors that allow it to evade the host immune response, leading to illness when introduced into the bloodstream, particularly in immunocompromised individuals.

In contrast, the other organisms listed are not as commonly associated with septic reactions in transfusion settings. Staphylococcus aureus is more related to skin flora and wound infections rather than the blood supply. Escherichia coli, while it can be involved in some blood infections, is less frequently implicated in transfusion reactions specifically. Clostridium perfringens is also known for its rapid onset of food poisoning and gas gangrene but is not a typical contaminant of blood products in the context of transfusion-associated sepsis.