Why are catheters a common source of nosocomial infection?

Catheters pass through the body's protective barriers and can carry pathogens directly into normally sterile areas, such as the bladder or bloodstream. That direct route makes infection more likely, so “Catheters provide a direct route for pathogens to enter the human body” is the best answer. Catheters can also harbor microbes, but the key risk described here is that they give pathogens a way inside.

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