Title: Methicillin-Resistant Staphylococcus aureus (MRSA)
1Antimicrobial (Drug) Resistance
Methicillin-Resistant Staphylococcus aureus
(MRSA)
- By Paul Parks RN
- Legal Nurse Consultant
2 Overview of MRSA
- During the past four decades, a type of bacteria
has evolved from a controllable nuisance into a
serious public health concern. This bacterium is
known as methicillin-resistant Staphylococcus
aureus, or MRSA. About one-third of people in the
world have S. aureus bacteria on their bodies at
any given time, primarily in the nose and on the
skin. The bacteria can be present without causing
an active infection. Of the people with S. aureus
present, about 1 percent has MRSA, according to
the Centers for Disease Control and Prevention
(CDC).
3MRSA can be categorized according to where the
infection was acquired hospital-acquired MRSA
(HA-MRSA) or community associated MRSA
(CA-MRSA).
4Hospital-acquired MRSA (HA-MRSA)
- HA-MRSA is acquired in the hospital setting and
is one of many hospital-acquired infections
exhibiting increased antimicrobial resistance.
HA-MRSA has increased during the past decade due
to a number of factors including an increased
number of immunocompromised and elderly patients,
an increase in the number of invasive procedures
e.g., advanced surgical operations and life
support treatments, and failures in infection
control measures such as hand washing prior to
patient contact and removal of non-essential
catheters.
5Community associated MRSA (CA-MRSA)
- CA-MRSA is caused by newly emerging strains
unlike those responsible for HA-MRSA and can
cause infections in otherwise healthy persons
with no links to healthcare systems. CA-MRSA
infections typically occur as skin or soft tissue
infections, but can develop into more invasive,
life-threatening infections. CA-MRSA is occurring
with increasing frequency in the United States
and around the world and tends to occur in
conditions where people are in close physical
contact, such as athletes involved in football
and wrestling, soldiers kept in close quarters,
inmates, childcare workers, and residents of
long-term care facilities.
6The History of Methicillin-Resistant
Staphylococcus aureus (MRSA)
- The S. aureus bacterium, commonly known as staph,
was discovered in the 1880s. During this era, S.
aureus infection commonly caused painful skin and
soft tissue conditions such as boils,
scalded-skin syndrome, and impetigo. More serious
forms of S. aureus infection can progress to
bacterial pneumonia and bacteria in the
bloodstreamboth of which can be fatal. S. aureus
acquired from improperly prepared or stored food
can also cause a form of food poisoning.
7 MRSA History
- In the 1940s, medical treatment for S. aureus
infections became routine and successful with the
discovery and introduction of antibiotic
medication, such as penicillin. - From that point on, however, use of
antibioticsincluding misuse and overusehas
aided natural bacterial evolution by helping the
microbes become resistant to drugs designed to
help fight these infections. In the late 1940s
and throughout the 1950s, S. aureus developed
resistance to penicillin.
8 History
- Methicillin, a form of penicillin, was introduced
to counter the increasing problem of
penicillin-resistant S. aureus. Methicillin was
one of most common types of antibiotics used to
treat S. aureus infections but, in 1961, British
scientists identified the first strains of S.
aureus bacteria that resisted methicillin. This
was the so-called birth of MRSA.
9 First Reported Case
- The first reported human case of MRSA in the
United States came in 1968. Subsequently, new
strains of bacteria have developed that can now
resist previously effective drugs, such as
methicillin and most related antibiotics. - MRSA is actually resistant to an entire class of
penicillin-like antibiotics called beta-lactams.
This class of antibiotics includes penicillin,
amoxicillin, oxacillin, methicillin, and others.
10 Evolution of S. Aureus
- S. aureus is evolving even more and has begun to
show resistance to additional antibiotics. In
2002, physicians in the United States documented
the first S. aureus strains resistant to the
antibiotic, vancomycin, which had been one of a
handful of antibiotics of last resort for use
against S. aureus. Though it is feared that this
could quickly become a major issue in antibiotic
resistance, thus far, vancomycin-resistant
strains are still rare at this time.
11 Transmission of MRSA
- Today, S. aureus has evolved to the point where
experts refer to MRSA in terms ranging from a
considerable public health burden to a crisis.
The bacteria have been classified into two
categories based on where infection is first
acquired. - The first category is Hospital Acquired-MRSA and
the second is Community-Associated-MRSA
12 Hospital-Acquired (HA)-MRSA
- HA-MRSA has been recognized for decades and
primarily affects people in healthcare settings,
such as those who have had surgery or medical
devices surgically implanted. This source of MRSA
is typically problematic for the elderly, for
people with weakened immune systems, and for
patients undergoing kidney dialysis or using
venous catheters or prosthetics.
13Hospital-Acquired (HA)-MRSA
- A study published in 2005 found that nearly 1
percent of all hospital in-patient stays, or
292,045 per year, were associated with S. aureus
infection. The study reviewed nearly 14 million
patient discharge diagnoses from 2000 and 2001.
Patients with diagnoses of S. aureus infection,
when compared with those without the infection,
had about three times the length of stay, three
times the total cost, and five times the risk of
in-hospital death. Notably, the S. aureus
infections in this hospital study resulted in
14,000 deaths.
14 Community-Associated (CA)-MRSA
- CA-MRSA has only been known since the 1990s.
CA-MRSA is of great concern to public health
professionals because of who it can affect.
Unlike the hospital sources, which usually can be
traced to a specific exposure, the origin of
CA-MRSA infection can be elusive. CA-MRSA skin
infections are known to spread in crowded
settings in situations where there is close
skin-to-skin contact when personal items such as
towels, razors, and sporting equipment is shared
when personal hygiene is compromised and when
healthcare is limited.
15 Community-Associated (CA)-MRSA
- Outbreaks of CA-MRSA have involved bacterial
strains with specific microbiologic and genetic
differences from traditional HA-MRSA strains, and
these differences suggest that community strains
might spread more easily from person to person
than HA-MRSA. While CA-MRSA is resistant to
penicillin and methicillin, they can still be
treated with other common-use antibiotics.
16Community-Associated (CA)-MRSA
- CA-MRSA most often enters the body through a cut
or scrape and appears in the form of a skin or
soft tissue infection, such as a boil or abscess.
The involved site is red, swollen, and painful
and is often mistaken for a spider bite. Though
rare, CA-MRSA can develop into more serious
invasive infections, such as bloodstream
infections or pneumonia, leading to a variety of
other symptoms including shortness of breath,
fever, chills, and death. CA-MRSA can be
particularly dangerous in children because their
immune systems are not fully developed.
17Community-Associated (CA)-MRSA
- You should pay attention to minor skin
problemspimples, insect bites, cuts, and
scrapesespecially in children. If the wound
appears to be infected, see a healthcare
provider. - Researchers continue to study information about
these cases in an attempt to determine why
certain groups of people become ill when exposed
to these strains. Researchers also continue to
try to understand why high-incidence areas may
appear. For example, for unknown reasons, severe
outbreaks have occurred in Alaska, Georgia, and
Louisiana.
18 Diagnosis of MRSA
- To diagnose S. aureus, a sample is obtained from
the infection site and sent to a microbiology
laboratory for testing. If S. aureus is found,
the organism should be further tested to
determine which antibiotic would be effective for
treatment. - Doctors often diagnose MRSA by checking a tissue
sample or nasal secretions for signs of
drug-resistant bacteria. Current diagnostic
procedures involve sending a sample to a lab
where it is placed in a dish of nutrients that
encourage bacterial growth (a culture).
19 Diagnosing MRSA
- It takes about 48 hours for the bacteria to
grow. However, newer tests that can detect staph
DNA in a matter of hours are now becoming more
widely available. This will help healthcare
providers decide on the proper treatment regimen
for a patient more quickly, after an official
diagnosis has been made. - In the hospital, you might be tested for MRSA if
you show signs of infection, or if you are
transferred to a hospital from another healthcare
setting where MRSA is known to be present. You
also might be tested if you have had a previous
history of MRSA.
20 Treatment for MRSA Infections
- Healthcare providers can treat many S. aureus
skin infections by draining the abscess or boil
and may not need to use antibiotics. Draining of
skin boils or abscesses should only be done by a
healthcare provider. - For mild to moderate skin infections, incision
and drainage by a healthcare provider is the
first-line treatment. Before prescribing
antibiotics, your provider will consider the
potential for antibiotic resistance.
21 Treatment for MRSA Infections
- Thus, if MRSA is suspected, your provider will
avoid treating you with beta-lactam antibiotics,
a class of antibiotic observed not to be
effective in killing the staph bacteria. For
severe infection, doctors will typically use
Vancomycin intravenously. - NOTE Vancomycin is extremely nephrotoxic and can
lead to acute renal failure (ARF). - Even with careful monitoring of peak and trough
levels acute renal failure is always a
possibility.
22 MRSA Prevention
- The best defense against spreading MRSA is to
practice good hygiene, as follows - Keep your hands clean by washing thoroughly with
soap and water. Scrub them briskly for at least
15 seconds, then dry them with a disposable towel
and use another towel to turn off the faucet.
When you dont have access to soap and water,
carry a small bottle of hand sanitizer containing
at least 62 percent alcohol. - Always shower promptly after exercising.
23 MRSA Prevention
- Keep cuts and scrapes clean and covered with a
bandage until healed. Keep wounds that are
draining or have pus covered with clean, dry
bandages. Follow your healthcare providers
instructions on proper care of the wound. Pus
from infected wounds can contain S. aureus and
MRSA, so keeping the infection covered will help
prevent the spread to others. Bandages or tape
can be discarded with regular trash. Avoid
contact with other peoples wounds or bandages.
Avoid sharing personal items, such as towels,
washcloths, razors, clothes, or uniforms.
24 MRSA Prevention
- Wash sheets, towels, and clothes that become
soiled with water and laundry detergent use
bleach and hot water if possible. Drying clothes
in a hot dryer, rather than air-drying, also
helps kill bacteria in clothes. Tell any
healthcare providers who treat you if you have or
had an S. aureus or MRSA skin infection. If you
have a skin infection that requires treatment,
ask your healthcare provider if you should be
tested for MRSA. Many healthcare providers
prescribe drugs that are not effective against
antibiotic-resistant staph, which delays
treatment and creates more resistant germs.
25 Researching the MRSA Superbug
- Healthcare providers are fighting back against
MRSA infection by tracking bacterial outbreaks
and by investing in products, such as
antibiotic-coated catheters and gloves that
release disinfectants. - Community-associated strains are notably
effective at causing severe infections in
otherwise healthy individuals and are different
from the strains that cause hospital infections.
As these strains begin to appear in hospitals
where immuno-compromised patients are at risk, it
becomes increasingly important to understand how
CA-MRSA can colonize and invade healthy people.
26 Researching MRSA
- The National Institute of Allergy and Infectious
Diseases (NIAID) funds basic and translational
research with the ultimate goal to develop and
promote enhanced diagnostics, better therapeutic
treatments, and new vaccines that are effective
against Methicillin-Resistant Staphylococcus
aureus (MRSA). Given the increasing prevalence of
MRSA in both hospital and community settings, it
is important to understand how MRSA spreads, the
factors that influence the severity of disease
(virulence factors), and how best to treat MRSA
infections.
27 Researching MRSA
- Virulence factors can include proteins that allow
the bacteria to adhere to and colonize the host,
to invade host cells, to inhibit the host immune
response, and to poison and damage host cells.
28 Virulence Associated Factors of Community-
Associated MRSA (CA-MRSA)
- Drs. Michael Otto and Frank DeLeo, and their
colleagues at NIAIDs Rocky Mountain Laboratories
(RML), recently described the essential role of
the phenol-soluble modulin (PSM) protein family
in CA-MRSA disease severity. These PSM proteins
are able to destroy most immune cells,
particularly white blood cells that help people
fight off infection. While these proteins may not
be the only virulence factors produced by
CA-MRSA, they have been identified as major
factors in the disease severity of CA-MRSA.
29How CA-MRSA Spreads Among Households
- Dr. Robert Daum, a researcher at the University
of Chicago, is seeking to determine the best
methods for containing, preventing, and treating
CA-MRSA infections by understanding the
circumstances that facilitate the transfer of
CA-MRSA among household members. The study will
determine how easily CA-MRSA is transferred from
the initial infected person to other members
within his/her household and at what rate
household members become colonized or infected
with CA-MRSA.
30The Spread of MRSA Among Households
- The rate of CA-MRSA spread among household
members will be compared to the rate of spread
that occurs between a person infected with
hospital-acquired MRSA (HA-MRSA), and other
members within a household.
31Strategies to Optimize the Use of Existing
Antibiotics for MRSA Therapy
- Two clinical trials are underway to define the
optimal treatment for skin and soft tissue
infections caused by CA-MRSA. CA-MRSA strains
have remained more susceptible to commonly
available antibiotics than hospital-associated
MRSA strains therefore, these trials will
evaluate how effective off-patent antimicrobials
are in treating uncomplicated cases of skin and
soft tissue infections caused by CA-MRSA
bacteria.
32Strategies to Optimize the Use of Existing
Antibiotics for MRSA Therapy
- Off-patent antimicrobials would be a
cost-effective means of treating these infections
and would alleviate the use of last-resort
antibiotics such as Vancomycin, which is
essential for the treatment of hospital-associated
MRSA.
33 A Few Facts About Vancomycin
- Vancomycin is indicated for the treatment of
serious, life-threatening infections by
Gram-positive bacteria which are unresponsive to
other less toxic antibiotics. In particular,
vancomycin should not be used to treat
methicillin-sensitive Staphylococcus aureus
because it is inferior to penicillins such as
nafcillin. - The increasing emergence of vancomycin-resistant
enterococci has resulted in the development of
guidelines for use by the Centers for Disease
Control (CDC) Hospital Infection Control
Practices Advisory Committee. These guidelines
restrict use of vancomycin.
34These guidelines restrict use of vancomycin to
the following indications
- treatment of serious infections caused by
susceptible organisms resistant to penicillins
(methicillin-resistant Staphylococcus aureus and
multi-resistant Staphylococcus epidermidis
(MRSE)) or in individuals with serious allergy to
penicillins - pseudomembranous colitis (relapse or unresponsive
to metronidazole treatment) - For treatment of infections caused by
gram-positive microorganisms in patients who have
serious allergies to beta-lactam antimicrobials.
35Restricted use of Vancomycin for the following
indications
-
- Antibacterial prophylaxis for endocarditis
following certain procedures in
penicillin-hypersensitive individuals at high
risk. -
- Surgical prophylaxis for major procedures
involving implantation of prostheses in
institutions with a high rate of MRSA or MRSE.
36Adverse effects of Vancomycin
- Although vancomycin levels are usually monitored,
in an effort to reduce adverse events, the value
of this is not beyond debate.15 Peak and trough
levels are usually monitored, and for research
purposes, the area under the curve is also
sometimes used. Toxicity is best monitored by
looking at trough values. - Common adverse drug reactions (1 of patients)
associated with IV vancomycin include local
pain, which may be severe and/or
thrombophlebitis.
37 Adverse effects of Vancomycin
- Damage to the kidneys and to the hearing were a
side effect of the early impure versions of
vancomycin, and these were prominent in the
clinical trials conducted in the mid-1950s. Later
trials using purer forms of vancomycin found that
nephrotoxicity is an infrequent adverse effect
(0.11 of patients), but that this is
accentuated in the presence of aminoglycosides.
38 Red man syndrome
- Vancomycin must be administered in a dilute
solution slowly, over at least 60 minutes
(maximum rate of 10 mg/minute for doses gt500 mg).
This is due to the high incidence of pain and
thrombophlebitis and to avoid an infusion
reaction known as the red man syndrome or red
neck syndrome. This syndrome, usually appearing
within 410 minutes after the commencement or
soon after the completion of an infusion, is
characterized by flushing and/or an erythematous
rash that affects the face, neck and upper torso.
These findings are due to non-specific mast cell
degranulation and are not an IgE mediated
allergic reaction
39 Red man syndrome
- . Less frequently, hypotension and angioedema may
also occur. Symptoms may be treated or prevented
with antihistamines, including diphenhydramine,
and are less likely to occur with slow infusion.
40Red Man Syndrome
41 The Effects of MRSA
42 MRSA
43 MRSA
44 The End
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