What causes a pyrogenic reaction in patients?

A pyrogenic reaction in patients is primarily caused by endotoxins, which are toxic substances released from the cell walls of certain types of bacteria, particularly Gram-negative bacteria, when they die or are lysed. Endotoxins can trigger a strong immune response when they enter the human body, leading to symptoms such as fever, chills, and malaise. This is because the immune system perceives these endotoxins as harmful invaders and responds vigorously, resulting in the release of cytokines that induce fever as part of the inflammatory response.

In contrast, allergens are substances that trigger allergic reactions but do not directly lead to pyrogenic responses. Microbial infections can cause fever, but they involve a broader range of pathogens and immune responses beyond just endotoxins. Chemical exposure can lead to various reactions, but it typically does not include the specific response associated with pyrogenic reactions. Thus, the role of endotoxins as agents capable of inducing fever distinctly categorizes them as the primary cause of pyrogenic reactions.