An infection that involves multiple sites and/or organs and tissues is classified as:

An infection that involves multiple sites and/or organs and tissues is classified as systemic. This type of infection indicates that the pathogens are not confined to a single area but rather spread throughout the body, affecting various systems or organs. For example, systemic infections may originate from a localized infection that disseminates through the bloodstream or lymphatic system, placing multiple organ systems at risk.

In contrast, a localized infection remains confined to a specific area of the body, such as a wound or a specific organ, affecting only that site without widespread impact. Focal infections involve a primary infection site that can affect other sites through spreading infection but typically still have a central focus. Generalized infections usually refer to conditions that affect the body as a whole but are not as precisely defined as systemic infections, which are characterized by their broad involvement. Thus, the term "systemic" accurately captures the nature of an infection that spans multiple locations and affects diverse tissues and organs within the body.