Indoor Air sciences CSMI Practice Exam

Where are endotoxins formed?

1. Cell wall of gram negative fungi

2. Cell wall of gram positive bacteria

3. Cell wall of gram positive fungi

4. Cell wall of gram negative bacteria

The correct answer is: Cell wall of gram negative bacteria

Endotoxins are a type of toxin that are specifically associated with gram-negative bacteria. These toxins are structurally integrated into the outer membrane of the cell wall of these bacteria. When the bacteria die or undergo lysis, the endotoxins are released into the surrounding environment, potentially triggering severe immune responses in the host. The significance of gram-negative bacteria in relation to endotoxins lies in their unique cell wall structure, which contains lipopolysaccharides (LPS). This component is essential for the function of the bacteria and is recognized by the immune system, often leading to inflammation and other physiological effects upon exposure. In contrast, gram-positive bacteria do not produce endotoxins as they lack an outer membrane and do not contain lipopolysaccharides. Instead, they may produce exotoxins, which are different in structure and function compared to endotoxins. Therefore, the correct identification of the source of endotoxins is central to understanding their impact on health and disease, clearly linking them to the cell wall of gram-negative bacteria.