Infectious agents, such as bacteria and viruses, pose a constant threat within healthcare environments, making the prevention of their spread a primary concern. Transmission occurs when a pathogen moves from an infected source to a susceptible host, often through contact with contaminated surfaces, droplets, or airborne particles. Healthcare settings rely on a structured, two-tiered system of infection prevention controls: Standard Precautions and Transmission-Based Precautions. This dual approach provides a foundational level of protection for every interaction and supplemental measures for specific, high-risk situations.
Standard Precautions: The Universal Baseline
Standard Precautions represent the first tier and are the foundation of infection control, applied universally to every patient encounter regardless of the individual’s known or suspected infection status. This approach is grounded in the principle that all body fluids, secretions, and excretions (except sweat), non-intact skin, and mucous membranes may potentially contain transmissible infectious agents.
Hand hygiene is a core component of this tier. Healthcare personnel must clean their hands using alcohol-based hand rub or soap and water before and after every patient contact, after touching the patient’s surroundings, and before and after performing clean or aseptic procedures.
The use of personal protective equipment (PPE) is required, selected based on the anticipated risk of exposure to bodily fluids. Gloves, gowns, and a mask or eye protection are used when contact with infectious materials is expected.
Safe injection practices are mandated to prevent the transmission of bloodborne pathogens. This requires using a new, sterile needle and syringe for every injection. Needles must never be recapped or manipulated after use and must be disposed of immediately in puncture-proof sharps containers.
Respiratory hygiene and cough etiquette focus on source control for individuals with respiratory symptoms. This involves covering the mouth and nose when coughing or sneezing, performing hand hygiene afterward, and, in some cases, wearing a surgical mask. Standard Precautions also include the safe handling of contaminated patient care equipment, soiled linens, and routine environmental cleaning.
Transmission-Based Precautions: When More is Needed
Transmission-Based Precautions constitute the second tier and are always used in addition to Standard Precautions. These supplemental measures are reserved for patients known or suspected to be infected or colonized with highly transmissible pathogens.
The application of these controls is based on the known or likely mode of spread for the specific infectious agent. There are three distinct categories within this tier: Contact, Droplet, and Airborne Precautions, each targeting a different pathway of transmission. The decision to initiate these precautions is often made empirically based on a patient’s clinical signs before a definitive laboratory diagnosis is available, allowing for immediate risk mitigation.
Categorizing Specific Transmission Routes
Contact Precautions
Contact Precautions are utilized for organisms spread through direct patient contact or indirect contact with contaminated environmental surfaces or items in the patient’s room. Examples include Clostridioides difficile and Methicillin-resistant Staphylococcus aureus (MRSA). A private patient room is generally required. Personnel must don a gown and gloves upon entry and remove them before exiting the room to prevent transfer of the organism. Reusable medical equipment, such as blood pressure cuffs or stethoscopes, should be dedicated solely to the isolated patient or thoroughly cleaned and disinfected before use on another individual.
Droplet Precautions
Droplet Precautions target the transmission of pathogens contained within larger respiratory droplets expelled during coughing, sneezing, or talking. These droplets typically travel short distances (less than three to six feet) before falling out of the air. These measures are necessary for infections like influenza, pertussis, and certain types of bacterial meningitis. Healthcare personnel must wear a surgical mask upon entering the patient’s room. While a private room is preferred, if unavailable, patients infected with the same organism may be cohorted, or separated by a minimum of three feet from other patients. Special air handling systems are not necessary for this type of isolation.
Airborne Precautions
Airborne Precautions are implemented for infections transmitted by small particles that remain suspended in the air and can travel over long distances on air currents. Diseases requiring this level of isolation include tuberculosis, measles, and varicella (chickenpox). The room must be an Airborne Infection Isolation Room (AIIR), also known as a negative pressure room, engineered to maintain lower air pressure than the surrounding areas. This specialized ventilation system ensures that air flows into the room, preventing contaminated air from escaping into the hallway or other patient areas. The room air is then exhausted directly outside or passed through a high-efficiency particulate air (HEPA) filter before recirculation. Personnel entering the room must wear a fit-tested N95 respirator or a higher level of respiratory protection, as a standard surgical mask is insufficient to filter the small airborne particles.
Ensuring Compliance and Safe Practices
The effectiveness of the two-tiered precaution system depends on the consistent and correct execution of every protocol. Staff education and ongoing training ensure that personnel understand the rationale behind each precaution and the specific actions required for compliance. Training must include detailed instruction on the correct sequence for donning (putting on) and doffing (taking off) personal protective equipment.
The process of doffing PPE is important because improper removal can lead to self-contamination, transferring infectious material to the wearer’s skin or clothing. Institutional oversight, often conducted by infection prevention specialists, monitors adherence through audits and direct observation. This continuous process of surveillance and feedback helps identify lapses in practice.
Leadership must ensure that adequate supplies of appropriate PPE, hand hygiene products, and dedicated equipment are readily available at the point of care.