Which organism is not typically associated with transfusion-transmitted bacterial contamination?

• A. Escherichia coli
• B. Yersinia enterocolitica
• C. Pseudomonas putida
• D. Citrobacter freundii

Answer: (A)

Transfusion-transmitted bacterial contamination comes from organisms that can survive and multiply in stored blood components, especially platelets kept at room temperature. Among the organisms listed, Yersinia enterocolitica, Pseudomonas putida, and Citrobacter freundii are classic culprits because they persist and grow under those storage conditions and have been repeatedly linked to septic transfusion reactions. Escherichia coli, while a common pathogen in general infections, is not typically highlighted as a frequent cause of TTBC in standard practice. It can contaminate products in some cases, but it’s not as commonly associated with transfusion-transmitted contamination as the others, making it the best choice for not being typical in this context.