biologicalcontrols.com - Isolation
Precautions
Recommendations
for Isolation Precautions in Hospitals
(Reproduced from CDC Web site, NOT the complete text)
RATIONALE
FOR ISOLATION PRECAUTIONS IN HOSPITALS
Transmission
of infection within a hospital requires three
elements: a source of infecting microorganisms,
a susceptible host, and a means of transmission
for the microorganism.
Transmission
Microorganisms
are transmitted in hospitals by several routes,
and the same microorganism may be transmitted
by more than one route. There are five
main routes of transmission: contact, droplet,
airborne, common vehicle, and vectorborne. For
the purpose of this guideline, common vehicle
and vectorborne transmission will be discussed
only briefly, because neither play a significant
role in typical nosocomial infections.
-
Contact
transmission, the most important and
frequent mode of transmission of nosocomial
infections, is divided into two subgroups: direct-contact
transmission and indirect-contact transmission.
-
Direct-contact
transmission involves a direct body
surface-to-body surface contact and
physical transfer of microorganisms
between a susceptible host and an infected
or colonized person, such as occurs
when a person turns a patient, gives
a bath, or performs other patient-care
activities that require direct personal
contact. Direct-contact transmission
also can occur between two patients,
with one serving as the source of the
infectious microorganisms and the other
as a susceptible host.
-
Indirect-contact
transmission involves contact of a
susceptible host with a contaminated intermediate
object, usually inanimate, such as
contaminated instruments, needles,
or dressings, or contaminated hands
that are not washed and gloves that
are not changed between patients.
-
Droplet
transmission, theoretically,
is a form of contact transmission. However,
the mechanism of transfer of the pathogen
to the host is quite distinct from either
direct or indirect - contact transmission. Therefore,
droplet transmission will be considered
a separate route of transmission in this
guideline. Droplets are generated
from the source person primarily during
coughing, sneezing, and talking, and
during the performance of certain procedures
such as suctioning and bronchoscopy. Transmission
occurs when droplets containing microorganisms
generated from the infected person are
propelled a short distance through the
air and deposited on the host's conjunctivae,
nasal mucosa, or mouth. Because
droplets do not remain suspended in the
air, special air handling and ventilation
are not required to prevent droplet transmission; that
is, droplet transmission must not be
confused with airborne transmission.
-
Airborne
transmission occurs by dissemination
of either airborne droplet nuclei (small-particle
residue [5 um
or smaller in size] of evaporated droplets
containing microorganisms that remain suspended
in the air for long periods of time) or
dust particles containing the infectious
agent. Microorganisms carried in
this manner can be dispersed widely by
air currents and may become inhaled by
a susceptible host within the same room
or over a longer distance from the source
patient, depending on environmental factors; therefore,
special air
handling and ventilation are
required to prevent airborne transmission. Microorganisms
transmitted by airborne transmission include
Mycobacterium tuberculosis and the rubeola
and caricella viruses.
Isolation
precautions are designed to prevent transmission
of microorganisms by these routes in hospitals. Because
agent and host factors are more difficult to
control, interruption of transfer of microorganisms
is directed primarily at transmission. The
recommendations presented in this guideline are
based on this concept.
Placing
patient on isolation
precautions, however, often presents
certain disadvantages to the hospital, patients,
personnel, and visitors. Isolation precautions
may require specialized equipment and environmental
modifications that add to the cost of hospitalizations. Isolation
precautions may take frequent visits by nurses,
physicians, and other personnel inconvenient,
and they may make it more difficult for personnel
to give the prompt and frequent care that sometimes
is required. The use of a multi-patient
room for one patient uses valuable space that
otherwise might accommodate several patients. Moreover,
forced solitude deprives the patient of normal
social relationships and may be psychologically
harmful, especially to children. These
disadvantages, however, must be weighed against
the hospital's mission to prevent the spread
of serious and epidemiologically important microorganisms
in the hospital.
FUNDAMENTALS
OF ISOLATION PRECAUTIONS
A
variety of infection control measures are used
for decreasing the risk of transmission of microorganisms
in hospitals. These measures make up the
fundamentals of isolation precautions.
Patient
Placement
Appropriate
patient placement is a significant component
of isolation
precautions. A private room
is important to prevent direct -or indirect-
contact transmission when the source patient
has poor
hygienic habits, contaminates the environment,
or cannot be expected to assist in maintaining
infection control precautions to limit transmission
of microorganisms (i.e., infants, children, and
patients with altered mental status). When
possible, a patient with highly transmissible
or epidemiologically important microorganisms
is place in a private room with handwashing and
toilet facilities, to reduce opportunities for
transmission of microorganisms.
When
a private room is not available, an infected
patient is placed with an appropriate roommate. Patients
infected by the same microorganism usually can
share a room, provided they are not infected
with other potentially transmissible microorganisms
and the likelihood of reinfection with the same
organism is minimal. Such sharing of rooms,
also referred to as cohorting patients, is useful
especially during outbreaks or when there is
a shortage of private rooms. When a private
room is not available and cohorting is not achievable
or recommended it is very important to
consider the epidemiology and mode of transmission
of the infecting pathogen and the patient population
being served in determining patient placement. Under
these circumstances, consultation with infection
control professionals is advised before patient
placement. Moreover, when an infected patient
shares a room with a noninfected patient, it
also is important that patients, personnel, and
visitors take precautions to prevent the spread
of infection and that roommates are selected
carefully.
Guidelines
for construction,
equipment, air handling, and ventilation for
isolation rooms have been delineated in other
publications. A private room with appropriate
air handling and ventilation is particularly
important for reducing the risk of transmission
of microorganisms from a source patient to susceptible
patients and other persons in hospitals when
the microorganism is spread by airborne transmission. Some
hospitals use isolation room with an anteroom
as an extra measure of precaution to prevent
airborne transmission. Adequate data regarding
the need for an anteroom, however, is not available. Ventilation
recommendations for isolation rooms housing patients
with pulmonary tuberculosis have been delineated
with other CDC guidelines.
HICPAC
ISOLATION PRECAUTIONS
There
are two tiers of HICPAC isolation precautions. In
the first, and most important, tier are those
precautions designed for the care of all patients
in hospitals, regardless of their diagnosis or
presumed infection status. Implementation
of these "Standard Precautions" is the primary
strategy for successful nosocomial infection
control. In the second tier are precautions
designed only for the care of specified patients. These
additional "Transmission-Based Precautions" are
for patients known or suspected to be infected
by epidemiologically important pathogens spread
by airborne or droplet transmission or by contact
with dry skin or contaminated surfaces.
Transmission-Based
Precautions
Transmission-Based
Precautions are designed for patients documented
or suspected to be infected with highly transmissible
or epidemiologically important pathogens for
which additional precautions beyond Standard
Precautions are needed to interrupt transmission
in hospitals. There are three types of
Transmission-Based Precautions: Airborne
Precautions, Droplet Precautions, and Contact
Precautions. They may be combined for diseases
that have multiple routes of transmission. When
used either singularly or in combination, they
are to be used in addition to Standard Precautions.
Airborne
Precautions are designed to reduce the
risk of airborne transmission of infectious
agents. Airborne transmission occurs
by dissemination of either airborne droplet
nuclei (small particle reside [5 um
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. Microorganisms
carried in this manner can be dispersed widely
by air currents and may become inhaled by or
deposited on a susceptible host within the
same room or over a longer distance from the
source patient, depending on environmental
factors; therefore, special air handling
and ventilation are required to prevent airborne
transmission. Airborne Precautions apply
to patient known or suspected to be infected
with epidemiologically important pathogens
that can be transmitted by the airborne route.
Droplet
Precautions are designed to reduce the
risk of droplet
transmission of infectious agents. Droplet
transmission involves contact of the conjunctivae
or the mucous membranes of the nose or mouth
of a susceptible person with large-particle
droplets (larger than 5 um
in size) containing microorganisms generated
from a person who has a clinical disease or
who is a carrier of the microorganism. Droplets
are generated from the source person primarily
during coughing, sneezing, or talking and during
the performance of certain procedures such
as suctioning and bronchoscopy. Transmission
via large-particle droplets requires close
contact between source and recipient persons,
because droplets do not remain suspended in
the air generally travel only short distances,
usually 3 ft or
less, through the air. Because droplets
do not remain suspended in the air, special
air handling and ventilation are not required
to prevent droplet transmission. Droplet
Precautions apply to any patient know or suspected
to be infected with epidemiologically important
pathogens that can be transmitted by infectious
droplets.
Airborne
Precautions
In
addition to Standard Precautions, use Airborne
Precautions, or the equivalent, for patients
known or suspected to be infected with microorganisms
transmitted by airborne droplet nuclei (small-particle
residue [5 um
or smaller in size] of evaporated droplets containing
microorganisms that remain suspended in the air
and that can be dispersed widely by air currents
within a room or over a long distance.
Patient Placement:
Place the patient in a private room that has:
-
Monitored
negative air pressure in relation to the
surrounding areas
-
6 to 12 air
changes per hour
-
Appropriate
discharge of air outdoors or monitored high-efficiency
filtration of room air before the air is
circulated to other areas in the hospital Keep
the room
door closed and the patient
in the room. When a private room is
not available, place the patient in a room
with a patient who has active infection with
the same microorganism, unless otherwise
recommended, but with no other infection. When
a private room in not available and cohorting
is not desirable, consultation with infection
control professionals is advised before patient
placement.
Droplet
Precautions
In
addition to Standard Precautions, use Droplet
Precautions, or the equivalent, for a patient
known or suspected to be infected with microorganisms
transmitted by droplets (large-particle droplets
[larger than 5 um
in size] that can generated by the patient during
coughing, sneezing, talking, or the performance
of procedures).
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