Which of the following is an example of direct damage due to bacterial infection?

• A. Fever induced by pyrogens
• B. Release of cytokines by host immune cells
• C. Activation of the host immune response leading to inflammation
• D. Destruction of host cells by bacterial toxins

Answer: (D)

Verified step by step guidance

1. Understand the concept of 'direct damage' in bacterial infections: it refers to harm caused directly by the bacteria or their products to host cells or tissues, rather than damage caused indirectly through the host's immune response.
2. Review each option and classify it as either direct or indirect damage. For example, fever induced by pyrogens is a systemic response triggered by bacterial components but mediated by the host's immune system, so it is indirect damage.
3. Recognize that the release of cytokines by host immune cells and activation of the host immune response leading to inflammation are both examples of indirect damage, as they involve the host's defense mechanisms reacting to the infection.
4. Identify that destruction of host cells by bacterial toxins is a direct effect because bacterial toxins are produced by the bacteria themselves and cause damage directly to host cells without requiring the host immune system to mediate the effect.
5. Conclude that the correct example of direct damage is the destruction of host cells by bacterial toxins, as this fits the definition of direct bacterial-induced harm.