Pathogenic bacteria are known for being:

Pathogenic bacteria are characterized by their ability to cause disease and harm to living organisms. These bacteria can invade bodily tissues and disrupt normal biological functions, leading to infections. In the context of cosmetology, understanding the nature of pathogenic bacteria is crucial since they can thrive in environments like salons, especially if proper sanitation and hygiene practices are not followed.

The other options do not accurately define pathogenic bacteria. Non-infectious and beneficial bacteria refer to those that play a role in processes like digestion or skin health, which contrasts sharply with pathogenic bacteria that are harmful. While certain bacteria might be used in cosmetic products for beneficial purposes, pathogenic bacteria are generally not sought after for such applications due to their undesirable effects. Lastly, pathogenic bacteria are not exclusively found in salons; they can exist in various environments, including on skin, in food, and in contaminated water. Understanding these distinctions is key to maintaining health and safety standards in the cosmetology field.