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TRANSMISSION-BASED PRECAUTIONS

KEY CONCEPTS you will learn include:
· What the reasons for the new Transmission-Based Precautions are
· What Transmission-Based Precautions are designed to do
· What preventive processes and practices are recommended for each
route of infection transmission
· How to effectively use Transmission-Based Precautions
BACKGROUND
Although the spread of infectious diseases in hospitals has been recognized for many years, understanding how to prevent nosocomial infections and implementing policies and practices that are successful has been more difficult. The transmission of nosocomial infections requires
three elements: a source of infecting microorganisms, a susceptible host
and a mode of transmission. The human source of nosocomial infections may be patients, hospital personnel or, less often, visitors. These people may have infectious diseases, be in the incubation period (no symptoms), or may be chronic carriers. Other sources of infecting microorganisms are inanimate objects that become contaminated, (e.g., instruments) and the environment, including air and water. Susceptible hosts are those patients, hospital personnel and, less often, visitors who may become infected. Resistance among people to infecting
microorganisms varies; for example, some are immune, others get infected and become asymptomatic carriers; and still others get infected and develop a clinical disease. Factors such as age, underlying diseases, treatment with certain drugs (e.g., antimicrobials, corticosteroids and other immunosupressive agents) and irradiation play a role in this process. The three main routes of infection transmission in hospitals are airborne, droplet and contact. An infecting microorganism, however, can be transmitted by more than one route. For example, varicella (chicken pox) is transmitted both by the airborne and contact route at different stages of
the disease. The purpose of this is to explain how Transmission-Based Precautions are
used in the hospital to minimize the risk of clients, patients, visitors and staff becoming infected while dealing with the healthcare system. Transmission-Based Precautions: Isolation Precaution Guidelines for Hospitals

DEFINITIONS
· Airborne transmission. Transfer of particles 5 μm or less in size into the air, either as airborne droplets or dust particles containing the microoganism; can be produced by coughing, sneezing, talking or procedures such as bronchoscopy or suctioning; can remain in the air for up to several hours and be spread widely within a room or over longer distances. Special air handling and ventilation are needed to prevent airborne transmission.
· Droplet transmission. Contact of the mucous membranes of the nose, mouth or conjunctivae of the eye with infectious particles larger than 5μm in size; can be produced by coughing, sneezing, talking or procedures such as bronchoscopy or suctioning. Droplet transmission requires close contact between the source and the susceptible person
because particles remain airborne briefly and travel only about 3 feet
(1 meter) or less.
· Contact transmission. Infectious agent (bacteria, virus or parasite) transmitted directly or indirectly from one infected or colonized person to a susceptible host (patient), often on the contaminated hands of a health worker.
· Colonization. Pathogenic (illness- or disease-causing) organisms are present in a person (i.e., they can be detected by culturing or other tests) but are not causing symptoms or clinical findings (i.e., cellular changes or damage). Coming in contact with and acquiring new organisms, while increasing the risk of infection, usually does not lead to infection because the body’s natural defense mechanism (the immune system) is able to tolerate and/or destroy them. Thus, when organisms are transmitted from one person to another, colonization rather than infection is generally the result. Colonized persons, however, can be a major source of transfer of pathogens to other persons (cross-contamination) especially if the organisms persist in the
person (chronic carrier), such as with HIV, HBV and HCV
TRANSMISSION-BASED PRECAUTIONS
The new isolation guidelines issued by CDC in 1996 involve a two-level approach: Standard Precautions, which apply to all clients and patients attending healthcare facilities, and Transmission-Based Precautions, which apply only to hospitalized patients (Garner and HICPAC 1996). This new system retains the best features of both Universal Precautions
(UP) and Body Substance Isolation (BSI) and replaces the cumbersome disease-specific isolation precautions with three sets of Transmission- Based Precautions (air, droplet or contact).
Note: Protective isolation of immunocompromised patients, such as those with AIDS, is not an effective way to reduce the risk of cross-infection (Mananganet al 2001).
Transmission-Based Precautions: Isolation Precaution Guidelines for Hospitals

In all situations, whether used alone or in combination, Transmission-Based Precautions must be used in conjunction with the Standard Precautions (Garner and HICPAC 1996).
Airborne Precautions These precautions are designed to reduce the nosocomia transmission of particles 5 μm or less in size that can remain in the air for several hours and be widely dispersed (Table 1). Microorganisms spread wholly or partly by the airborne route include tuberculosis (TB), chicken pox (varicella virus) and measles (rubeola virus). Airborne precautions are recommended for patients with either known or suspected infections with
these agents. For example, an HIV-infected person with a cough, night sweats or fever, and clinical or x-ray findings in the lungs should go on airborne precautions until TB is ruled out.
Where TB is prevalent, it is important to have a mechanism to quickly assess patients with suspected TB because delayed diagnosis, resulting in lack of isolation, has been shown to be an important factor in hospitalbased transmission. In this situation, airborne precautions are the last defense in reducing the risk of TB transmission.
Table 1. Airborne Precautions
Used in addition to Standard Precautions for a patient known or suspected to be infected
with microorganisms transmitted by the airborne route.
PATIENT PLACEMENT
· Private room.
· Door closed.
· Room air is exhausted to the outside (negative air pressure) using fan or other filtration system.
· If private room not available, place patient in room with patient having active infection with the same disease, but with no other infection.
RESPIRATORY PROTECTION
· Wear face shield (or goggles and surgical mask)
· If TB known or suspected, wear particulate respirator (if available).
· If chicken pox or measles:
- Immune persons, no mask required.
- Susceptible persons, do not enter room.
· Remove PPE (face shield) after leaving the room and place in a plastic bag or waste container with tight-fitting lid.
PATIENT TRANSPORT
· Limit transport of patient to essential purposes only.
· During transport, patient must wear surgical mask.
· Notify area receiving patient.
Adapted from: Infection Control Signs, www.etnacomm.com, ETNA Communications, Chicago, IL. Copyright 2000.
Transmission-Based Precautions: Isolation Precaution Guidelines for Hospitals

Droplet Precautions These precautions reduce the risks for nosocomial transmission of pathogens spread wholly or partly by droplets larger than 5 μm in size (e.g., H. influenzae and N. meningitides meningitis; M. pneumoniae, flu, mumps and rubella viruses). Other conditions include diphtheria, pertussis (whooping cough), pneumonic plague and strep pharyngitis (scarlet fever in infants and young children). Droplet precautions are simpler than airborne precautions because the particles only remain in the air for a short time and travel only a few feet;
therefore, contact with the source must be close for a susceptible host to become infected.
Table 2. Droplet Precautions
Use in addition to Standard Precautions for a patient known or suspected to be infected
with microorganisms transmitted by large-particle droplets (larger than 5 μm).
PATIENT PLACEMENT
· Private room; door may be left open.
· If private room not available, place patient in room with patient having active infection with the same disease, but with no other infection.
· If neither option is available, maintain separation of at least 3 feet between patients.
RESPIRATORY PROTECTION
· Wear mask if within three feet of patient.
PATIENT TRANSPORT
· Limit transport of patient to essential purposes only.
· During transport, patient must wear surgical mask.
· Notify area receiving patient.
Adapted from: Infection Control Signs, www.etnacomm.com, ETNA Communications, Chicago, IL. Copyright 2000.
Contact Precautions These precautions reduce the risk of transmission of organisms from an
infected or colonized patient through direct or indirect contact (Table 3). They are indicated for patients infected or colonized with enteric pathogens (hepatitis A or echo viruses), herpes simplex and hemorrhagic fever viruses and multidrug (antibiotic)-resistant bacteria. Interestingly, chicken pox is spread both by the airborne and contact routes at different stages of the illness. Among infants there are a number of viruses transmitted by direct contact. In addition, Contact Precautions should be implemented for patients with skin or eye infections that may be contagious (e.g., draining abscesses, skin infections that are wet and draining, herpes zoster, impetigo, conjunctivitis, scabies, lice and wound infections).
Transmission-Based Precautions: Isolation Precaution Guidelines for Hospitals

Table 3. Contact Precautions
Use in addition to Standard Precautions for a patient known or suspected to be infected or colonized with microorganisms transmitted by direct contact with the patient or indirect contact with environmental surfaces or patient care items.
PATIENT PLACEMENT
· Private room; door may be left open.
· If private room not available, place patient in room with patient having active infection with the same microorganism, but with no other infection.
GLOVING
· Wear clean, nonsterile examination gloves when entering room.
· Change gloves after contact with infective material (e.g., fecal materials or wound drainage).
· Remove gloves before leaving patient room.
HANDWASHING
· Wash hands with antibacterial agent or use alcohol-based handrub after removing gloves.
· Do not touch potentially contaminated surfaces or items before leaving the room.
GOWNS AND PROTECTIVE APPAREL
· Wear clean, nonsterile gown when entering patient room if you anticipate contact with patient or if the patient is incontinent, has diarrhea, an ileostomy, colostomy or wound drainage not
contained by a dressing.
· Remove gown before leaving room. Do not allow clothing to contact potentially contaminated surfaces or items before leaving the room.
PATIENT TRANSPORT
· Limit transport of patient to essential purposes only.
· During transport, ensure precautions are maintained to minimize risk of transmission of organisms.
PATIENT CARE EQUIPMENT
· Reserve noncritical patient care equipment for use with a single patient, if possible.
· Clean and disinfect any equipment shared among infected and noninfected patients.
Adapted from: Infection Control Signs, www.etnacomm.com, ETNA Communications, , IL. Copyright 2000.


Transmission-Based Precautions: Isolation Precaution Guidelines for Hospitals

Table 4. Empiric Use of Transmission Based Precautions

AIRBORNE DROPLET CONTACT
· rashes (vesicule or pustule)
· cough, fever and upper lobe chest findings
(dullness anddecreased breath sounds)
· cough, fever and chest findings in any area in HIV-infected person or at high-risk for HIV
· meningitis (fever, vomiting and stiff neck)
· hemorrhagic rash with fever
· severe, persistent cough during periods
when pertussis is present in community
· generalized rash of unknown cause
· acute diarrhea in an incontinent or diapered patient
· diarrhea in adult with history of recent antibiotic use
· bronchitis and croup in infants and young children
· history of infection with multi-resistant organisms (except tuberculosis)
· abscess or drainingwound that cannot be covered
The use of Transmission-Based Precautions, including their empiric use in selected circumstances, is designed to reduce the risk of airborne-, dropletand contact-transmitted infections between hospitalized patients andhealthcare staff. To assist health workers in correctly implementing theappropriate precautions, Table 6 provides a summary of the types of
isolation precautions and the illnesses for which each type of precaution is recommended. In addition, Appendix I provides a complete listing of the types and duration of the isolation precautions needed for the vast majorityof infectious diseases.
Empiric Use ofTransmission-BasedPrecautions
In certain circumstances, if there is any question of an infectious process in a patient without a known diagnosis, implementing Transmission-BasedPrecautions should be considered on an empiric basis until a definitive diagnosis is made. Examples of the “empiric use” of Transmission-Based Precautions as they apply to the three routes (air, droplet and contact) are
illustrated in Table 4. In addition, a complete listing of clinical syndromes or conditions warranting the empiric use of Transmission-Based Precautions is shown in Table 5. From time to time and based on local conditions, other important infectious diseases should be considered for addition to this list.
Note: Unfortunately “reminder signs” for isolation patients do not use (compliance) with infection precautions (Manangan et al 2001). Unfortunately,
Transmission-Based Precautions: Isolation Precaution Guidelines for Hospitals

Table 6. Summary of Types of Precautions and Patients Requiring the Precautions
Standard Precautions
Use Standard Precautions for the care of all patients.
Airborne Precautions
In addition to Standard Precautions, use Airborne Precautions for patients known or suspected to have serious illnesses transmittedby airborne droplet nuclei. Examples of such illnesses include:
Measles
Varicella (including disseminated zoster)a
Tuberculosis b
Droplet Precautions
In addition to Standard Precautions, use Droplet Precautions for patients known or suspected to have serious illnesses transmitted by large particle droplets. Examples of such illnesses include:
Invasive Haemophilus influenzae type b disease, including meningitis, pneumonia, epiglottitis, and sepsis
Invasive Neisseria meningitidis disease, including meningitis, pneumonia, and sepsis
Other serious bacterial respiratory infections spread by droplet transmission, including:
Diphtheria (pharyngeal)
Mycoplasma pneumonia
Pertussis
Pneumonic plague
Streptococcal (group A) pharyngitis, pneumonia, or scarlet fever in infants and young children
Serious viral infections spread by droplet transmission, including:
Adenovirusa
Influenza
Mumps
Parvovirus B19
Rubella
Contact Precautions
In addition to Standard Precautions, use Contact Precautions for patients known or suspected to have serious illnesses easily transmitted by direct patient contact or by contact with items in the patient's environment.
Examples of such illnesses include:
Gastrointestinal, respiratory, skin, or wound infections or colonization with multidrug-resistant bacteria judged by the infection control program, based on current state, regional, or national recommendations, to be of special clinical and epidemiologic significance.
Enteric infections with a low infectious dose or prolonged environmental survival, including:
Clostridium difficile
For diapered or incontinent patients: enterohemorrhagic Escherichia coli O157:H7, Shigella, hepatitis A, or rotavirus,
Respiratory syncytial virus, parainfluenza virus, or enteroviral infections in infants and young children
Skin infections that are highly contagious or that may occur on dry skin, including:
Diphtheria (cutaneous)
Herpes simplex virus (neonatal or mucocutaneous)
Impetigo
Major (noncontained) abscesses, cellulitis, or decubiti
Pediculosis
Scabies
Staphylococcal furunculosis in infants and young children
Zoster (disseminated or in the immunocompromised host)†
Viral/hemorrhagic conjunctivitis
Viral hemorrhagic infections (Ebola, Lassa, or Marburg)*

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