Transmission-based precautions are infection-control precautions in health care, in addition to the so-called "standard precautions". They are the latest routine infection prevention and control practices applied for patients who are known or suspected to be infected or colonized with infectious agents, including certain epidemiologically important pathogens, which require additional control measures to effectively prevent transmission.
Infection prevention and control of epidemic- and pandemic-prone acute respiratory diseases in health care, WHO Interim Guidelines.2007 p. 53 Universal precautions are also important to address as far as transmission-based precautions. Universal precautions is the practice of treating all bodily fluids as if it is infected with HIV, HBV, or other blood borne pathogens.
Transmission-based precautions build on the so-called "standard precautions" which institute common practices, such as hand hygiene, respiratory hygiene, personal protective equipment protocols, soiled equipment and injection handling, patient isolation controls and risk assessments to limit spread between patients.
History The following table shows the history of guidelines for transmission-based precautions in U.S. hospitals as of 2007: Year Document issued Comment 1970National Communicable Disease Center. Isolation Techniques for Use in Hospitals. 1st ed. Washington, DC: US Government Printing Office;. PHS publication no 2054 1970 Isolation Technique for Use in Hospitals, 1st ed. Introduced seven isolation precaution categories with color-coded cards: Strict, Respiratory, Protective, Enteric, Wound and Skin, Discharge, and Blood. No user decision-making required. Simplicity a strength; over isolation prescribed for some infection.1975Garner JS, Simmons BP. CDC Guideline for Isolation Precautions in Hospitals. Atlanta, GA: US Department of Health and Human Services, Public Health Service, Centers for Disease Control; 1983. HHS publication no. (CDC) 83-8314. Infect Control 1983;4:245-325. Isolation Techniques for Use in Hospitals, 2nd ed. Same conceptual framework as 1st edition.1983 CDC Guideline for Isolation Precautions in Hospitals Provided two systems for isolation: category-specific and disease-specific. Protective Isolation eliminated; Blood Precautions expanded to include Body Fluids. Categories included Strict, Contact, Respiratory, AFB, Enteric, Drainage/Secretion, Blood and Body Fluids. Emphasized decision-making by users. 1985-88CDC. Update: universal precautions for prevention of transmission of human immunodeficiency virus, hepatitis B virus, and other bloodborne pathogens in health-care settings. MMWR Morb Mortal Wkly Rep 1988;37(24):377-82, 87-8.CDC. Recommendations for preventing transmission of infection with human T- lymphotropic virus type III/lymphadenopathy-associated virus in the workplace. MMWR Morb Mortal Wkly Rep 1985;34(450:681-6, 91-5. Universal precautions Developed in response to HIV/AIDS epidemic. Dictated application of Blood and Body Fluid precautions to all patients, regardless of infection status. Did not apply to feces, nasal secretions, sputum, sweat, tears, urine, or vomitus unless contaminated by visible blood. Added personal protective equipment to protect health care workers from mucous membrane exposures. Handwashing recommended immediately after glove removal. Added specific recommendations for handling needles and other sharp devices; concept became integral to OSHA's 1991 rule on occupational exposure to blood-borne pathogens in healthcare settings.1987Lynch P, Jackson MM, Cummings MJ, Stamm WE. Rethinking the role of isolation practices in the prevention of nosocomial infections. Ann Intern Med 1987;107(2):243-6. Body substance isolation Emphasized avoiding contact with all moist and potentially infectious body substances except sweat even if blood not present. Shared some features with Universal Precautions. Weak on infections transmitted by large droplets or by contact with dry surfaces. Did not emphasize need for special ventilation to contain airborne infections. Handwashing after glove removal not specified in the absence of visible soiling.1996Garner JS. Guideline for isolation precautions in hospitals. The Hospital Infection Control Practices Advisory Committee. Infect Control Hosp Epidemiol 1996;17(1):53-80.(s). Guideline for Isolation Precautions in Hospitals Prepared by the Healthcare Infection Control Practices Advisory Committee (HICPAC). Melded major features of Universal Precautions and Body Substance Isolation into standard precautions to be used with all patients at all times. Included three transmission-based precaution categories: airborne, droplet, and contact . Listed clinical syndromes that should dictate use of empiric isolation until an etiological diagnosis is established.
Rationale for use in healthcare setting Communicable diseases occur as a result of the interaction between a source (or reservoir) of infectious agents, a mode of transmission for the agent, a susceptible host with a portal of entry receptive to the agent, the environment. The control of communicable diseases may involve changing one or more of these components, the first three of which are influenced by the environment. These diseases can have a wide range of effects, varying from silent infection – with no signs or symptoms – to severe illness and death. According to its nature, a certain infectious agent may demonstrate one or more following modes of transmission direct and indirect contact transmission, droplet transmission and airborne transmission.Bonita, Ruth et al.. Basic epidemiology. 2nd edition. World Health Organization. 226 p., 2006
Transmission-based precautions are used when the route(s) of transmission is (are) not completely interrupted using "standard precautions" alone.
Standard precautions Standard precautions include: Hand hygiene or hand washing to prevent oneself from contracting an illness or disease and prevent the spread of pathogens (e.g. bacteria, viruses, parasites) to other people, thus reducing the potential for transmission. Hand hygiene can be accomplished with different modalities including alcohol-based hand sanitizers, soap and water, or antiseptic hand wash. There are techniques and benefits to using one modality over another. Utilization of alcohol-based hand sanitizer is generally recommended when the hands are not visibly soiled or before and after contact with a person (e.g. patient in a healthcare setting), or object. With proper technique, soap and water are preferred for visibly soiled hands or in situations where hands various pathogens cannot be killed with alcohol-based hand sanitizers (e.g. spore-producing organisms like Clostridioides difficile). personal protective equipment (PPE) in cases of infectious material exposure etiquette, respiratory hygiene principles, patient isolation controls, soiled equipment handling, and injection handling.
Research Research studies in the form of randomized controlled trials and simulation studies are needed to determine the most effective types of personal protective equipment for preventing the transmission of infectious diseases to healthcare workers. There is low-quality evidence that supports making improvements or modifications to personal protective equipment to help decrease contamination. Examples of modifications include adding tabs to masks or gloves to ease removal and designing protective gowns so that gloves are removed at the same time. In addition, there is weak evidence that the following PPE approaches or techniques may lead to reduced contamination and improved compliance with PPE protocols: Wearing double gloves, following specific doffing (removal) procedures such as those from the CDC, and providing people with spoken instructions while removing PPE.
Definitions Three categories of transmission-based precautions have been designed with respect to the modes of transmission, namely Contact precautions, Droplet precautions, and Airborne precautions. For some diseases with multiple routes of transmission, more than one transmission-based precautions category may be used. When used either singly or in combination, they are always used in addition to standard precautions.
Contact precautions
Contact precautions are intended to prevent transmission of infectious agents, including epidemiologically important microorganisms, which are spread by direct or indirect contact with the patient or the patient's environment. The specific agents and circumstance for which contact precautions are indicated are found in Appendix A of the 2007 CDC Guidance. The application of contact precautions for patients infected or colonized with Multidrug-Resistant Organisms MDROs is described in the 2006 HICPAC/CDC MDRO guideline.Management of Multidrug-Resistant Organisms In Healthcare Settings, 2006. 2006. www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf Contact precautions also apply where the presence of excessive wound drainage, fecal incontinence, or other discharges from the body suggest an increased potential for extensive environmental contamination and risk of transmission. A single-patient room is preferred for patients who require contact precautions. When a single-patient room is not available, consultation with infection control personnel is recommended to assess the various risks associated with other patient placement options (e.g., cohorting, keeping the patient with an existing roommate). In multi-patient rooms, >3 feet spatial separation between beds is advised to reduce the opportunities for inadvertent sharing of items between the infected/colonized patient and other patients. Healthcare personnel caring for patients on contact precautions wear a gown and gloves for all interactions that may involve contact with the patient or potentially contaminated areas in the patient's environment. Donning PPE upon room entry and discarding before exiting the patient room is done to contain pathogens, especially those that have been implicated in transmission through environmental contamination (e.g., VRE, C. difficile, noroviruses and other intestinal tract pathogens; RSV)Donskey CJ. The role of the intestinal tract as a reservoir and source for transmission of nosocomial pathogens. Clin Infect Dis 2004;39(2):219-26.Bhalla A, Pultz NJ, Gries DM, et al. Acquisition of nosocomial pathogens on hands after contact with environmental surfaces near hospitalized patients. Infect Control Hosp Epidemiol 2004;25(2):164-7.Duckro AN, Blom DW, Lyle EA, Weinstein RA, Hayden MK. Transfer of vancomycin-resistant enterococci via health care worker hands. Arch Intern Med 2005;165(3):302-7.Hall CB, Douglas RG, Jr. Modes of transmission of respiratory syncytial virus. J Pediatr 1981;99(1):100-3.Evans MR, Meldrum R, Lane W, et al. An outbreak of viral gastroenteritis following environmental contamination at a concert hall. Epidemiol Infect 2002;129(2):355-60.Wu HM, Fornek M, Kellogg JS, et al. A Norovirus Outbreak at a Long-Term-Care Facility: The Role of Environmental Surface Contamination. Infect Control Hosp Epidemiol 2005;26(10):802-10.CDC. Recommendations for preventing the spread of vancomycin resistance. Recommendations of the Hospital Infection Control Practices Advisory Committee (HICPAC). MMWR Recomm Rep 1995;44 (RR12):1-13.
Droplet precautions
As of 2020, the classification systems of routes of respiratory disease transmission are based on a conceptual division of large versus small droplets, as defined in the 1930s.Wells WF. On air-borne infection: study II. Droplets and droplet nuclei. American Journal of Hygiene 1934;20:611-8.