Current Trends
Acquired Immune Deficiency Syndrome (AIDS): Precautions for
Clinical and Laboratory Staffs
The etiology of the underlying immune deficiencies seen in AIDS
cases is unknown. One hypothesis consistent with current
observations
is that a transmissible agent may be involved. If so, transmission
of
the agent would appear most commonly to require intimate, direct
contact involving mucosal surfaces, such as sexual contact among
homosexual males, or through parenteral spread, such as occurs
among
intravenous drug abusers and possibly hemophilia patients using
Factor
VIII products. Airborne spread and interpersonal spread through
casual contact do not seem likely. These patterns resemble the
distribution of disease and modes of spread of hepatitis B virus,
and
hepatitis B virus infections occur very frequently among AIDS
cases.
There is presently no evidence of AIDS transmission to hospital
personnel from contact with affected patients or clinical
specimens.
Because of concern about a possible transmissible agent, however,
interim suggestions are appropriate to guide patient-care and
laboratory personnel, including those whose work involves
experimental
animals. At present, it appears prudent for hospital personnel to
use
the same precautions when caring for patients with AIDS as those
used
for patients with hepatitis B virus infection, in which blood and
body
fluids likely to have been contaminated with blood are considered
infective. Specifically, patient-care and laboratory personnel
should
take precautions to avoid direct contact of skin and mucous
membranes
with blood, blood products, excretions, secretions, and tissues of
persons judged likely to have AIDS. The following precautions do
not
specifically address outpatient care, dental care, surgery,
necropsy,
or hemodialysis of AIDS patients. In general, procedures
appropriate
for patients known to be infected with hepatitis B virus are
advised,
and blood and organs of AIDS patients should not be donated.
The precautions that follow are advised for persons and
specimens
from persons with: opportunistic infections that are not
associated
with underlying immunosuppressive disease or therapy; Kaposi's
sarcoma
(patients under 60 years of age); chronic generalized
lymphadenopathy,
unexplained weight loss and/or prolonged unexplained fever in
persons
who belong to groups with apparently increased risks of AIDS
(homosexual males, intravenous drug abusers, Haitian entrants,
hemophiliacs); and possible AIDS (hospitalized for evaluation).
Hospitals and laboratories should adapt the following suggested
precautions to their individual circumstances; these
recommendations
are not meant to restrict hospitals from implementing additional
precautions.
The following precautions are advised in providing care to
AIDS patients:
Extraordinary care must be taken to avoid accidental
wounds
from sharp instruments contaminated with potentially
infectious material and to avoid contact of open skin
lesions
with material from AIDS patients.
Gloves should be worn when handling blood specimens,
blood-soiled items, body fluids, excretions, and
secretions,
as well as surfaces, materials, and objects exposed to
them.
Gowns should be worn when clothing may be soiled with body
fluids, blood, secretions, or excretions.
Hands should be washed after removing gowns and gloves and
before leaving the rooms of known or suspected AIDS
patients. Hands should also be washed thoroughly and
immediately if they become contaminated with blood.
Blood and other specimens should be labeled prominently
with
a special warning, such as "Blood Precautions" or "AIDS
Precautions." If the outside of the specimen container is
visibly contaminated with blood, it should be cleaned with
a
disinfectant (such as a 1:10 dilution of 5.25% sodium
hypochlorite (household bleach) with water). All blood
specimens should be placed in a second container, such as
an
impervious bag, for transport. The container or bag
should
be examined carefully for leaks or cracks.
Blood spills should be cleaned up promptly with a
disinfectant solution, such as sodium hypochlorite (see
above).
Articles soiled with blood should be placed in an
impervious
bag prominently labeled "AIDS Precautions" or "Blood
Precautions" before being sent for reprocessing or
disposal.
Alternatively, such contaminated items may be placed in
plastic bags of a particular color designated solely for
disposal of infectious wastes by the hospital. Disposable
items should be incinerated or disposed of in accord with
the
hospital's policies for disposal of infectious wastes.
Reusable items should be reprocessed in accord with
hospital
policies for hepatitis B virus-contaminated items. Lensed
instruments should be sterilized after use on AIDS
patients.
Needles should not be bent after use, but should be
promptly
placed in a puncture-resistant container used solely for
such
disposal. Needles should not be reinserted into their
original sheaths before being discarded into the
container,
since this is a common cause of needle injury.
Disposable syringes and needles are preferred. Only
needle-locking syringes or one-piece needle-syringe units
should be used to aspirate fluids from patients, so that
collected fluid can be safely discharged through the
needle,
if desired. If reusable syringes are employed, they
should
be decontaminated before reprocessing.
A private room is indicated for patients who are too ill
to
use good hygiene, such as those with profuse diarrhea,
fecal
incontinence, or altered behavior secondary to central
nervous system infections.
Precautions appropriate for particular infections that
concurrently occur in AIDS patients should be added to the above,
if
needed.
B. The following precautions are advised for persons
performing
laboratory tests or studies on clinical specimens or other
potentially infectious materials (such as inoculated tissue
cultures, embryonated eggs, animal tissues, etc.) from known or
suspected AIDS cases:
Mechanical pipetting devices should be used for the
manipulation of all liquids in the laboratory. Mouth
pipetting should not be allowed.
Needles and syringes should be handled as stipulated in
Section\A (above).
Laboratory coats, gowns, or uniforms should be worn while
working with potentially infectious materials and should
be
discarded appropriately before leaving the laboratory.
Gloves should be worn to avoid skin contact with blood,
specimens containing blood, blood-soiled items, body
fluids,
excretions, and secretions, as well as surfaces,
materials,
and objects exposed to them.
All procedures and manipulations of potentially infectious
material should be performed carefully to minimize the
creation of droplets and aerosols.
Biological safety cabinets (Class I or II) and other
primary
containment devices (e.g., centrifuge safety cups) are
advised whenever procedures are conducted that have a high
potential for creating aerosols or infectious droplets.
These include centrifuging, blending, sonicating, vigorous
mixing, and harvesting infected tissues from animals or
embryonated eggs. Fluorescent activated cell sorters
generate droplets that could potentially result in
infectious
aerosols. Translucent plastic shielding between the
droplet-collecting area and the equipment operator should
be
used to reduce the presently uncertain magnitude of this
risk. Primary containment devices are also used in
handling
materials that might contain concentrated infectious
agents
or organisms in greater quantities than expected in
clinical
specimens.
Laboratory work surfaces should be decontaminated with a
disinfectant, such as sodium hypochlorite solution (see A5
above), following any spill of potentially infectious
material and at the completion of work activities.
All potentially contaminated materials used in laboratory
tests should be decontaminated, preferably by autoclaving,
before disposal or reprocessing.
All personnel should wash their hands following completion
of
laboratory activities, removal of protective clothing, and
before leaving the laboratory.
C. The following additional precautions are advised for
studies
involving experimental animals inoculated with tissues or other
potentially infectious materials from individuals with known or
suspected AIDS.
Laboratory coats, gowns, or uniforms should be worn by
personnel entering rooms housing inoculated animals.
Certain
nonhuman primates, such as chimpanzees, are prone to throw
excreta and to spit at attendants; personnel attending
inoculated animals should wear molded surgical masks and
goggles or other equipment sufficient to prevent
potentially
infective droplets from reaching the mucosal surfaces of
their mouths, nares, and eyes. In addition, when handled,
other animals may disturb excreta in their bedding.
Therefore, the above precautions should be taken when
handling them.
Personnel should wear gloves for all activities involving
direct contact with experimental animals and their bedding
and cages. Such manipulations should be performed
carefully
to minimize the creation of aerosols and droplets.
Necropsy of experimental animals should be conducted by
personnel wearing gowns and gloves. If procedures
generating
aerosols are performed, masks and goggles should be worn.
Extraordinary care must be taken to avoid accidental
sticks
or cuts with sharp instruments contaminated with body
fluids
or tissues of experimental animals inoculated with
material
from AIDS patients.
Animal cages should be decontaminated, preferably by
autoclaving, before they are cleaned and washed.
Only needle-locking syringes or one-piece needle-syringe
units should be used to inject potentially infectious
fluids
into experimental animals.
The above precautions are intended to apply to both clinical
and
research laboratories. Biological safety cabinets and other safety
equipment may not be generally available in clinical laboratories.
Assistance should be sought from a microbiology laboratory, as
needed,
to assure containment facilities are adequate to permit laboratory
tests to be conducted safely.
Reported by Hospital Infections Program, Div of Viral Diseases, Div
of
Host Factors, Div of Hepatitis and Viral Enteritis, AIDS Activity,
Center for Infectious Diseases, Office of Biosafety, CDC; Div of
Safety, National Institutes of Health.
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