What is the most likely cause of initial hypotension in a patient with sepsis and E. coli bacteremia?

• A. Excessive production of nitric oxide
• B. Generation of hydrogen peroxide
• C. Hemorrhage
• D. Induction of endothelial adhesion molecules

Answer: (A)

In sepsis, particularly with E. coli bacteremia, the initial hypotension is primarily caused by excessive production of nitric oxide. This occurs as a result of the systemic inflammatory response triggered by the infection. Lipopolysaccharides (LPS) from bacteria like E. coli stimulate the immune system, leading to the release of various pro-inflammatory cytokines. These cytokines activate various pathways, including the inducible nitric oxide synthase (iNOS) pathway, resulting in increased levels of nitric oxide (NO).

The release of NO causes vasodilation, which is the widening of blood vessels. When blood vessels dilate, there is a decrease in vascular resistance, leading to a drop in blood pressure. This vasodilatory effect is significant in sepsis as it contributes to the characteristic hypotension observed in these patients. The resultant hypotension can lead to inadequate organ perfusion and subsequent organ dysfunction if not addressed promptly.

Considering the other options, while oxidative stress might contribute to the pathophysiology of sepsis, the generation of hydrogen peroxide is not a direct cause of hypotension. Hemorrhage, on the other hand, would cause hypotension through blood loss, but that is not the initial mechanism in sepsis. Induction of