What is the primary effect of pathogenic bacteria?

Pathogenic bacteria are microorganisms that invade the body and can cause diseases. Their primary effect is detrimental, leading to various infections and health complications. These bacteria have specific mechanisms through which they can disrupt normal bodily functions, evade the immune system, and produce toxins that contribute to disease manifestations.

The other options suggest positive roles that bacteria can play, such as supporting the immune system, increasing nutrient absorption, or enhancing bodily functions. However, pathogenic bacteria are involved specifically in harmful processes that result in illness, making disease causation their primary effect.