What do we call harmless microorganisms that do not cause disease?

The term used to describe harmless microorganisms that do not cause disease is "non-pathogenic." These microorganisms exist in numerous environments and can actually play beneficial roles, such as aiding in digestion or protecting the skin from harmful pathogens. Non-pathogenic bacteria are a normal part of human flora and can contribute to maintaining a healthy balance in various ecosystems.

In contrast, pathogenic microorganisms are those that can cause disease and harm to the host. Atypical refers to microorganisms that do not fit the standard classification or behaviors seen in their typical forms, often associated with atypical infections. The term bacterial is simply a broader category that includes all bacteria, which can be both pathogenic and non-pathogenic. Understanding these distinctions is essential in infection control practices, especially in settings like barbering, where maintaining the health of both the client and practitioner is paramount.