Resource Packages: Standard and Transmission Based Precautions
Historical Overview
Universal blood and body fluid precautions (Universal Precautions) were originally outlined by the Centers for Disease Control and Prevention (CDC) in 1985, largely due to the HIV epidemic and an urgent need for new strategies to protect hospital personnel from blood borne pathogens.
Universal Precautions, as defined by the CDC, applied to blood and body fluids that had been implicated in the transmission of blood borne infections (semen and vaginal secretions), body fluids from which the risk of transmission was unknown (amniotic, cerebrospinal, pericardial, peritoneal, pleural and synovial fluids) and to any other body fluid visibly contaminated with blood. Universal Precautions did not apply to faeces, nasal secretions, sputum, sweat, tears, urine or vomitus unless they contained visible blood.
Australia adopted a broader definition of Universal Precautions. All blood and body substances were considered to be potentially infectious. The principle was applied universally to all patients regardless of their infectious state or perceived risk.
By 1994 there was confusion in the interpretation of Universal Precautions and Body Substance Isolation as well as a false sense of security in its application. In view of the problems and concerns what was needed was a new synthesis of the various systems that would provide a guideline with logistically feasible recommendations for preventing the many infections that occur in hospitals through diverse modes of transmission.
To achieve this, the new guideline would have to be:
- Epidemiologically sound
- Recognise the importance of all body fluids, secretions and excretions in the transmission of nosocomial pathogens
- Contain adequate precautions for infections transmitted by the airborne, droplet and contact routes of transmission
- Be as simple as possible; and· use new terms to avoid confusion with existing systems
Recent Developments
On the basis of these considerations, guidelines were developed for Standard Precautions and Transmission-Based Precautions. These guidelines were designed to reduce the risk of transmission of blood borne and other pathogens, both recognised and unrecognised sources of infection in hospitals.
This change in terminology reflects a two tiered approach based on modes of disease transmission, and is in line with changes in terminology adopted by CDC.
As a result of this union, a large number of patients with diseases or conditions that previously required category or disease specific precautions, are now covered under Standard Precautions and do not require additional precautions.
Standard Precautions are work practices required for the basic level of infection control. They include good hygiene practices, particularly washing and drying hands before and after patient contact, the use of protective barriers which may include the wearing of gloves, gowns, plastic aprons/gowns, masks, eye shields or goggles, and the appropriate handling and disposal of sharps as well as other clinical waste, and following aseptic techniques.
Standard Precautions apply to:
- Blood
- All body substances, secretions and excretions except sweat, regardless of whether or not they contain visible blood
- Non-intact skin
- Mucous membranes
A variety of infection control measures are used for decreasing the risk of the spread or the transmission of microorganisms in hospitals. These measures include:
- Handwashing and handcare are considered the most important measures in infection control. Hands must be washed before and after patient contact. Hands must be washed immediately and thoroughly if contaminated with blood or body substances
- Gloves must be worn when in contact with blood or body substances. Gloves must be changed before and between patient contacts and hands must be washed after removal of gloves. Wearing gloves does not replace the need for handwashing
- Protective aprons or gowns are worn when there is a likelihood of splashes or splattering of blood or body substances
- Masks, protective eyewear and face shields are worn where there is a likelihood of splashes or splattering of blood or body substances
- Safe handling and disposal of needles and other sharp objects is important. Each health care worker who uses sharps is responsible for their management and disposal. Sharps containers should be placed as close as practicable to the point of use to limit the distance between use and disposal
Transmission-Based Precautions
Are used for patients known or suspected to be infected or colonised with epidemiologically important pathogens for which additional precautions beyond Standard Precautions are needed to interrupt transmission in health care facilities.
There are three types of transmission-based precautions:
A combination may be required for diseases that have multiple routes of transmission. The use of transmission-based precautions must always be in addition to standard precautions.
Airborne Precautions
- Apply to patients known or suspected to be infected with epidemiologically important pathogens that can be transmitted by the airborne route such as Mycobacterium tuberculosis, measles virus, Varicella (chickenpox) and Haemorrhagic fever, eg Ebola
- Designed to reduce the risk of airborne transmission of infectious agents. Airborne transmission occurs by dissemination of either airborne droplet nuclei (small-particle residue [5mm or smaller in size] of evaporated droplets that may remain suspended in the air for long periods of time) or dust particles containing the infectious agent
- Guidelines for the application of Transmission-Based Precautions for the management of Mycobacterium tuberculosis infected patients can be found in Controlling Tuberculosis in New South Wales
Droplet Precautions
- Apply to any patient known to be or suspected of being infected with epidemiologically important pathogens that can be transmitted by infectious droplets such as mumps, rubella, pertussis, influenza, Neisseria meningitidis, diphtheria and Pneumonic plague
- Designed to reduce the risk of droplet transmission of infectious agents. Droplet transmission involves contact of the conjunctivae or the mucous membranes of the mouth or nose of a susceptible person with large particle droplets (larger than 5mm in size) containing micro-organisms generated from a person who has a clinical disease or who is a carrier of the micro-organism. Because droplets do not remain suspended in the air, special air handling and ventilation are not required to prevent droplet transmission
Contact Precautions
- Designed to reduce the risk of transmission of epidemiologically important micro-organisms by direct or indirect contact such as colonisation of Multi Resistant Staphylococcus Aureus (MRSA), Vancomycin Resistant Enterococcus (VRE), Respiratory Syncytial Virus (RSV), highly contagious skin infections such as scabies, lice and impetigo, hepatitis A, Shigella and other gastroenteritis
- Direct contact-transmission involves skin-to-skin contact and physical transfer of micro-organisms to a susceptible host from an infected or colonised person, such as occurs when health care workers turn patients, bathe patients, or perform other patient-care activities that require physical contact
- Direct contact transmission can also occur between patients (eg by hand contact), with one serving as the source of infectious micro-organisms and the other as susceptible host. Indirect-contact transmission involves contact of a susceptible host with a contaminated intermediate object, usually inanimate, in the patient’s environment
Empiric Use of Airborne, Droplet or Contact Precautions
In many instances, the risk of nosocomial transmission of infection may be highest before a definitive diagnosis can be made and before precautions based on that diagnosis can be implemented.
The routine use of Standard Precautions for all patients should greatly reduce this risk for conditions other than those requiring Airborne, Droplet, or Contact Precautions.
While it is not possible to prospectively identify all patients needing these enhanced precautions, certain clinical syndromes and conditions carry a sufficiently high risk to warrant the empiric addition of enhanced precautions while a definitive diagnosis is pursued.
References
NSW Health Department, Controlling Tuberculosis in New South Wales, 1994.
Guideline for isolation precautions in hospitals. Part11. Recommendations for isolation precautions in hospitals. Hospital Infection Control Practices Advisary Committee, American Journal of Infection Control, 1996; 24:32-52
National Health and Medical Research Council’s (NHMRC) and the Australian National Council on AIDS, 1996, Infection Control in the Health Care Setting. Guidelines for the Prevention of Transmission of Infectious Diseases.
NSW Health Department, Infection Control Policy. 99/87. AIDS/ infectious Diseases Branch, 1999.
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