[Isolation precautions--transmission-based precautions].

There are two tiers of precautions to prevent transmission of infectious agents, standard precautions and transmission-based precautions. Standard precautions are intended to be applied to the care of all patients in all healthcare settings, regardless of the suspected or confirmed presence of an infectious agent. Transmission-based precautions are for patients who are known or suspected to be infected or colonized with infectious agents, which require additional control measures to effectively prevent transmission. Transmission-based precautions are used empirically, according to the likely etiologic agents at the time, and then modified when the pathogen is identified or a transmissible infectious etiology is ruled out. Implementation of preventive measures should be based on infection control risk assessment.