Transmission-Based Precautions are a set of infection control practices used in healthcare settings when a specific infectious agent is suspected or confirmed. These precautions are implemented in addition to the standard precautions applied to all patients, which include basic hand hygiene and routine use of personal protective equipment (PPE). The primary objective is to interrupt the known or suspected routes of transmission, preventing the spread to other patients, staff, and visitors. Precautions are often started empirically based on a patient’s symptoms or clinical syndrome and adjusted once laboratory confirmation is available. These protocols are categorized into three types based on how the pathogen moves: Contact, Droplet, and Airborne.
Contact Precautions
Contact Precautions prevent the spread of infections transmitted through direct physical contact with the patient or indirect contact with contaminated equipment or surfaces in the patient’s immediate environment. Direct contact occurs through touching the patient, while indirect contact involves touching items like bed rails or medical devices. This transmission route is relevant for pathogens that can survive on environmental surfaces.
Healthcare personnel entering the room must don a gown and gloves. This PPE must be put on before entering and carefully removed and discarded before exiting to contain infectious agents. Common examples include Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-resistant Enterococci (VRE).
For Clostridioides difficile (C. difficile), which forms spores, hand hygiene must be performed with soap and water. Alcohol-based sanitizers are not effective against these spores.
Droplet Precautions
Droplet Precautions are used for infections spread through large respiratory droplets generated when an infected person coughs, sneezes, or talks. These droplets measure more than 5 micrometers in size, causing them to travel only short distances before falling. The effective travel range is typically between three and six feet from the source.
The primary barrier is a surgical or procedure mask, which healthcare workers must wear upon entering the room. If the patient is transported out of their room, they should also wear a surgical mask to contain their own respiratory secretions. Specialized air handling systems are not required because the droplets do not remain suspended over long distances. Infections like influenza, pertussis (whooping cough), and some forms of meningitis require Droplet Precautions.
Airborne Precautions
Airborne Precautions are implemented for pathogens that spread via tiny particles, known as droplet nuclei, measuring 5 micrometers or less. These small particles remain suspended in the air for extended periods and travel long distances on air currents. This route represents the highest level of transmission risk, requiring the strictest control measures.
Patients must be placed in a single-occupancy room with specific engineering controls, known as an Airborne Infection Isolation Room (AIIR) or negative pressure room. This room maintains lower air pressure than the hallway, ensuring air flows into the room when the door is opened. The air is exhausted directly outside or through a High Efficiency Particulate Air (HEPA) filter. Healthcare personnel must wear a specialized, fit-tested N95 respirator before entering to filter out these minute particles. Diseases such as tuberculosis, measles, and varicella (chickenpox) require Airborne Precautions.
Criteria for Initiating and Discontinuing Precautions
The decision to begin Transmission-Based Precautions is often made empirically, based on a patient’s symptoms before a definitive laboratory diagnosis is available. For instance, a patient presenting with a specific rash and fever might be immediately placed on Airborne Precautions while awaiting test results. This syndromic approach ensures that transmission is prevented during the period of diagnostic uncertainty.
Discontinuing precautions depends on the specific infectious agent and the patient’s clinical status. For infections such as C. difficile, precautions may be stopped at least 48 hours after diarrhea has resolved. For other pathogens, such as MRSA or VRE, discontinuation may require one to three negative laboratory cultures. If a patient is not tested, the decision may be based on a time-based strategy, which calculates the duration from the onset of symptoms and the resolution of fever.