| Virulence
of MRSA
Identifying MRSA
Colonization and Infection
Risk Factors for MRSA
Procedures for obtaining cultures
to identify MRSA
Standard Precautions
Termination of Precautions
Communication
References
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MRSA FAQ
Introduction and Background
The term “methicillin-resistant Staphylococcus aureus”
(MRSA) refers to those strains of Staphylococcus aureus bacteria
that have acquired resistance to the antibiotics methicillin,
oxacillin, nafcillin, cephalosporins, imipenem, and/or other beta-lactam
antibiotics. The incidence of MRSA has increased in health care
facilities in the United States since the mid-1970s. Approaches
to the control of MRSA vary widely, primarily because studies
establishing the efficacy of specific infection control measures
are lacking.
This guideline recommends the most widely used approaches to
the control of MRSA in long term care facilities, including nursing
homes, chronic care and rehabilitation hospitals, extended care
facilities, assisted living facilities, etc. These approaches
include:
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Recognition of infected or colonized residents;
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Appropriate infection control measures;
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Communications between acute care and long
term care facilities; and
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Personnel policies related to MRSA.
Once MRSA has become firmly established in a facility,
it is rarely eliminated. A variety of control measures have been
reported, and many of these reports cite beneficial results. It
should be emphasized, however, that the efficacy of most measures
used for surveillance, prevention, and control of MRSA has not
been established in controlled studies. As a result, recommendations
in this guideline are based on general infection control principles
and on review of published articles dealing with the epidemiology
and control of MRSA in hospitals and long term care facilities.
See Attachment
1 for definition of terms associated with MRSA.
Virulence of MRSA
MRSA is not a “super bug.” While Staphylococcus
aureus itself is a virulent (disease causing) pathogen, methicillin
resistant strains are NOT more virulent than methicillin sensitive
strains. Many health care workers (HCWs) incorrectly assume that
MRSA strains are more virulent because of the special isolation
precautions implemented. MRSA is of special concern because it is
often multi-drug resistant, thus limiting treatment options.
Identifying MRSA
MRSA is identified by a bacterial culture and antibiotic
sensitivity of the suspected site of infection or colonization (e.g.,
blood, sputum, urine, wound, exudate, pressure ulcer material).
Two criteria are necessary for the organism to be identified as
MRSA. First, the organism is identified as Staphylococcus aureus
or coagulase-positive Staphylococcus species. Second, the antibiotic
sensitivity test will show that the organism is resistant to oxacillin,
methicillin, nafcillin, cephalosporins, imipenem, and/or other beta-lactam
antibiotics.
Colonization and Infection
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Colonization is the presence, growth, and multiplication
of the organism in one or more body sites without observable
clinical symptoms or immune reaction. A ‘carrier’
refers to an individual who is colonized with MRSA. MRSA colonization
can occur on the skin surface, wound or pressure ulcer surface,
in the sputum, or in the urine. One of the most common sites
of colonization in both HCWs and residents is the anterior nares.
While personnel may become colonized with MRSA, they rarely
develop infections with the organism.
- MRSA infection is a condition whereby the bacteria has invaded
a body site, is multiplying in tissue, and is causing clinical
manifestations of disease, such as fever, suppurative wound, pneumonia
or other respiratory illness or symptoms, or other signs of inflammation
(warmth, redness, swelling). Infection is confirmed by positive
cultures from sites such as blood, urine, sputum, or wound.
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Colonized and infected residents serve as the
major reservoir of MRSA in long term care facilities. Contaminated
environmental surfaces have not been shown to play a significant
role during outbreaks in long term care facilities. Asymptomatic
colonization of residents’ noses with MRSA is common in
long term care facilities. Point prevalence studies have found
that 23% - 35% of residents in Veterans’ Affairs affiliated
units may become colonized over a period of one to two years.
In the few prevalence surveys performed in freestanding long
term care facilities located in areas where MRSA is common,
9% - 12% of residents were colonized. MRSA colonization may
disappear with treatment and reappear weeks or months later.
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The main mode of transmission of MRSA is person
to person via hands, usually of HCWs. Colonization of
hands of personnel may be either transient, such as a single
day, or of longer duration, such as several weeks. Colonization
of the HCW may occur if proper handwashing and barriers (such
as gowns and gloves) are not used appropriately.
- MRSA may be aerosolized in the droplet nuclei from a coughing
resident or from a ventilator exhaust port of an intubated resident
who has MRSA in his or her sputum. The organism may also be aerosolized
during the irrigation of a wound containing MRSA. However,
the role of aerosolization in the transmission of MRSA is not
known. Although MRSA has been isolated from environmental
surfaces, transmission to residents is thought to be minimal,
except in burn units.
Risk Factors for MRSA
The following factors have been identified as increasing the
risk that a resident will have an MRSA infection:
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Prior prolonged hospitalization
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Preceding antimicrobial therapy
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Close proximity to a resident colonized or infected
with MRSA
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Presence of open wounds and/or pressure ulcers
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Presence of invasive devices, such as gastrostomy
tubes, tracheostomy tubes, intravascular lines, indwelling urinary
catheters, etc.
Procedures for Obtaining Cultures to Identify
MRSA
- Surface cultures of broken skin or weeping lesions
If a culture is needed from broken skin, a pressure ulcer,
etc., gently wipe area with a sterile gauze pad moistened with
saline. The site should then be swabbed with the culture swab,
using a rolling motion. If a Gram stain is indicated, an additional
swab should be taken from the site for the Gram stain. If the
site is suppurative (pus producing) or shows tissue destruction,
culture the area most heavily involved. Indicate the anatomical
location of the site that was cultured on the culture requisition
form. Gloves must be worn while obtaining cultures. Gloves should
then be removed, placed in the appropriate waste disposal unit,
and hands should be thoroughly washed with soap and water.
Surveillance
- The long term care facility should maintain a line listing
of the names and other appropriate information of residents and
admissions that are found to be colonized or infected with MRSA.4
(See Attachment
2)
- Do not include on the line listing residents who are colonized
with MRSA in the nares ONLY. These colonized patients should be
tracked separately.
- Facilities should regularly monitor and record endemic MRSA
case rates using incidence or incidence density ratio (e.g., percent
cases or cases per 1,000 resident-days).
Definition of an outbreak
An outbreak of MRSA in the facility represents an increase in
the incidence of MRSA cases in the facility above the baseline
level, or a clustering of new MRSA cases that are epidemiologically
linked. For the purposes of this guideline, an outbreak consists
of either:
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1) an increase in the average monthly incidence
of MRSA of 25% above the baseline, or
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2) three or more new MRSA cases within a two
month period on any ward or unit.
If an outbreak has been identified, notify the local health
department. Management of the outbreak should be conducted in
consultation with the local health department and DHMH. (See
Attachment 3)
These precautions must be used for ALL residents, regardless
of diagnosis or presumed infection status, when contact is anticipated
with blood; all body fluids, secretions, excretions, including
feces and urine but excluding sweat; nonintact skin; and mucous
membranes. Standard precautions consist of the following components:
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Routine handwashing, using soap, running
water, and friction must be strictly adhered to. In certain
circumstances, hands may be cleansed with an alcohol-based waterless
hand cleaner (containing at least 60% alcohol) between washing
with soap and water.
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Single use, disposable gloves must be
used when touching blood and all body fluids, nonintact skin,
and mucous membranes. Those employees who are sensitive to latex
may use latex-free gloves. The gloves may be sterile or non-sterile,
depending upon the task to be performed.
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Masks, eye protection, or face shields
must be worn when it is anticipated that splashing with body
fluids might occur, such as during suctioning of the respiratory
tract or irrigation of a large wound.
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Gowns must be worn when soiling of the
health care worker’s clothes is possible during care,
such as giving a resident a bath.
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Routine cleaning of resident care equipment
must be performed according to facility protocol.
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Routine cleaning of environmental surfaces
must be performed according to facility protocol.
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Linen must not be separated on the nursing
unit. ALL linen, regardless of the diagnosis of the resident,
should be collected and bagged at the bedside. If linen is wet,
or saturated with urine or feces, it should be collected in
a plastic or fluid impervious bag. The concept of “isolation
linen,” in which linen is collected and handled separately
according to the diagnosis of the resident, is no longer practiced.
All linen is treated in the same manner, i.e., as if it were
potentially infectious.
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Safe disposal of sharps, including needles,
must be accomplished according to facility protocol, the Occupational
Safety and Health Administration (OSHA) Bloodborne Pathogen
Standard, and State and local regulations
Contact precautions must be used when a resident is colonized
or infected with MRSA in any site other than the nares.
Nasal colonization of a resident with MRSA does not warrant precautions
other than standard precautions unless that resident is
considered to be epidemiologically linked, either as a source
or as a spread case, to an outbreak of MRSA in the facility.
Contact precautions consist of the following components:
Contact precautions must be used when a resident is colonized
or infected with MRSA IN ANY SITE OTHER THAN THE NARES.
Nasal colonization of a resident with MRSA does not warrant precautions
other than standard precautions unless that resident is considered
to be epidemiologically linked, either as a source or as a spread
case, to an outbreak of MRSA in the facility. Contact precautions
consist of the following components:
1. Room Placement and Activities
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A resident who is colonized or infected with
MRSA at any body site other than the nares should be placed
according to the following scheme:
-
Most Desirable: A private room or cohorting
with another resident who is colonized/infected with MRSA.
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Less Desirable: A room with another
resident who has intact skin and no “tubes” (invasive
feeding tubes, tracheotomy tubes, any type of intravascular
line, any type of indwelling urinary drainage tube, or any other
tube or device that breaks the skin or enters into a normal
body orifice).
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A resident with MRSA should not be placed with
another resident who has another antibiotic resistant organism,
e.g., vancomycin-resistant enterococcus (VRE).
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A resident may attend activities as long as
any colonized or infected body site, other than the nares, can
be securely covered, and the resident observes acceptable hygiene
and washes his/her hands.
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A resident who is unable to control secretions
should not attend group activities.
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A resident with nasal colonization of MRSA does
not need to wear a mask outside of the room and may attend all
activities. If the resident has a "cold" with significant
nasal discharge, they do not need a mask if they can control
their secretions and cover their nose and mouth when coughing
and sneezing.
| IF IT IS ALREADY KNOWN THAT A RESIDENT
HAS MRSA ONLY IN THE NOSE, IT IS PREFERABLE TO FOLLOW THE
ABOVE PLACEMENT GUIDELINES WHEN POSSIBLE, EVEN THOUGH THE
RESIDENT DOES NOT NEED TO BE PLACED ON CONTACT PRECAUTIONS.
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Special emphasis should be placed on handwashing for these residents.
If the resident’s cognition is less than normal, the nursing
personnel caring for them should be responsible for ensuring that
the resident washes his/her hands regularly and especially after
coughing and sneezing.
A resident who is colonized with MRSA in the sputum does not
need to wear a mask outside of the room if he/she can cover his/her
mouth and nose with a tissue when coughing. If they have a chronic,
uncontrollable cough, they should wearmask when outside of the
room. If they have a tracheostomy tube, the tube can be covered
with a “trach collar.” Again, special emphasis on
handwashing should be maintained on these residents. Placement
of these residents should follow the guidelines previously stated.
A resident who is infected (not colonized) with MRSA in the
respiratory tract, such as pneumonia or bronchitis, should wear
a mask when leaving the room.
2. Gloves
Nonsterile exam gloves (latex or latex-free) must be worn when
physical contact with the resident is anticipated and discarded
when soiled, before touching a clean surface and before leaving
the room.
3. Handwashing
Hands must be washed with an antimicrobial soap or alcohol-based
waterless hand cleanser after removing gloves and before leaving
the room. Care should be taken not to touch environmental surfaces
in the room before leaving, unless a disposable paper towel is
used to touch the surfaces.
4. Gowns
Gowns must be worn if physical contact with the resident will
occur, and changed between residents. Dispose of according to
facility protocol.
5. Masks
HCWs must wear a mask when the possibility of splashing in the
worker’s face is present, such as when suctioning respiratory
secretions or irrigation of large wounds. Residents who are infected
(not colonized) with MRSA in the respiratory tract, e.g. pneumonia
or bronchitis, should wear a mask when leaving the room. Those
residents who are colonized with MRSA in their sputum and who
have a chronic, uncontrollable cough should wear a mask when leaving
the room.
6. Equipment
Where possible, dedicate the use of personal, noncritical medical
equipment, such as thermometers and blood pressure apparatus,
to the resident with MRSA.
7. Cleaning
The resident’s room must be cleaned per protocol with
the facility’s hospital disinfectant-detergent. No special
cleaning methods are necessary.
Decolonization
Because colonized or infected residents represent the major reservoir
of MRSA, eradicating the organism from all such residents should
theoretically reduce the reservoir of MRSA in the facility. Decolonization
generally involves the use of topical and/or systemic antibiotic
treatment to eliminating MRSA carriage in an individual. While this
approach has been used in a number of hospitals and long term care
facilities, it has resulted in emergence of antibiotic resistance
in some cases.
Eradication of MRSA colonization may be desired by the physician
and the resident in situations where isolation may interfere with
the resident’s well being. Eradication may also be used during
MRSA outbreaks to help control the spread of the organism. Since
the use of single antimicrobial agents to eradicate MRSA may be
unsuccessful and may result in the emergence of resistance, MRSA
eradication should only be attempted in consultation with an infectious
disease physician.
Termination of Precautions
A resident may be considered free of MRSA after two cultures
of the colonized or infected body site is negative (except for
nares). The first culture should be taken 72 hours or more after
antibiotic treatment has been discontinued. The second culture
should be taken one week after the first. If the first or second
of these cultures remains positive for MRSA, cultures should continue
to be taken one week apart until two consecutive negative cultures
have been documented.
If a sputum specimen cannot be obtained from a resident who
has been colonized/infected with MRSA in the sputum, the resident’s
throat may be cultured as a surrogate for sputum.
If a wound site is healed, the healed site itself may be cultured
with a moist swab, according to procedures stated elsewhere in
this guideline.
When two consecutive negative cultures have been obtained, contact
precautions may be discontinued and standard precautions should
be followed for the resident.
Using cultures of a resident’s nares as criteria for discontinuing
contact precautions is not necessary and should not be done. Negative
nares culture from a resident does not necessarily provide adequate
evidence that the MRSA has been eradicated from that resident.
Prevalence surveys have shown that residents may be colonized
with MRSA in the absence of infection and without the knowledge
of the health care staff. Therefore, a resident’s nares
should ONLY be cultured if the resident is implicated in
a MRSA outbreak situation and NOT as a condition for termination
of contact precautions.
Long term care facilities may NOT arbitrarily refuse
to accept a resident with MRSA colonization or infection, as long
as the facility is able to place the resident according to the
room placement scheme mentioned previously.
Code of Maryland Regulations (COMAR) 10.07.02., July 1998, “Comprehensive
Care Facilities and Extended Care Facilities”, Section .08,
G. (1) “Admission and Discharge,” states: “A
facility may not deny admission to, or involuntarily discharge,
an individual solely because the individual has a communicable
disease.”
Long term care facilities should have some system in place for
alerting HCWs and visitors that a resident is on contact precautions,
such as labeling the chart or the door of the room, without compromising
that resident's privacy.
Long term care facilities should inform hospitals or other
nursing facilities if they transfer a resident who is known to
be colonized or infected with MRSA.
Hospitals and other nursing facilities that transfer a resident
known to be colonized or infected with MRSA to a long term care
facility should inform that facility that the resident has MRSA.
The transferring facility should also note, if it can be determined,
that the resident was infected or colonized with MRSA during the
hospitalization.
An MRSA patient in an hospital or other nursing facility who
transfers to a long term care facility does NOT need to have two
negative MRSA cultures before transfer can occur. Negative cultures
serve as criteria for discontinuing contact precautions only.
Training and Education
Certified nursing assistants (CNAs) and other HCWs in the facility
should receive basic instruction in performing infection control
procedures. Each facility must also periodically present continuing
education on handwashing, standard and transmission-based precautions,
and the OSHA Bloodborne Pathogen Standard.
When a resident acquires MRSA, appropriate infection control
procedures should be reviewed with all HCWs who will have contact
with the resident.
Surveillance cultures of HCWs for MRSA carriage is not recommended
as a general control measure. Such cultures should be done only
if employees are epidemiologically implicated as the source of an
outbreak, as directed by DHMH personnel.
Personnel who have staphylococcal infection should be treated
with antibiotics. Personnel with skin lesions or dermatitis should
be removed from direct resident care until the lesions are healed.
Personnel with respiratory infections and cough should not be assigned
to direct resident care.
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