What is the main complication associated with bacterial contamination in blood transfusions?

The main complication associated with bacterial contamination in blood transfusions is sepsis and shock. Bacterial contamination can occur when blood products are not handled or stored correctly, allowing bacterial growth to proliferate. When transfused, these bacteria can enter the recipient's bloodstream, leading to a severe systemic response known as sepsis. This condition is characterized by fever, chills, elevated heart rate, and, if severe enough, can progress to septic shock, a life-threatening condition where blood pressure drops dangerously low due to the body's response to the infection.

In contrast, febrile reactions typically occur due to the recipient's immune response to white blood cells or cytokines in the transfused blood, rather than direct bacterial infection. Iron overload primarily arises from repeated blood transfusions, which can lead to excess iron accumulation in the body, but it is unrelated to bacterial contamination. Delayed hemolytic reactions involve the destruction of transfused red blood cells due to the recipient's immune response to minor blood group antigens; these reactions are usually not a direct consequence of bacterial contamination. Thus, sepsis and shock are the critical complications specifically linked to the presence of bacteria in blood products.