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Title: Methicillin-Resistant Staphylococcus aureus (MRSA)


1
Antimicrobial (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).

3
MRSA can be categorized according to where the
infection was acquired hospital-acquired MRSA
(HA-MRSA) or community associated MRSA
(CA-MRSA).
4
Hospital-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.

5
Community 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.

6
The 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.

13
Hospital-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.

16
Community-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.

17
Community-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.

29
How 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.

30
The 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.

31
Strategies 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.

32
Strategies 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.

34
These 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.

35
Restricted 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.

36
Adverse 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.

40
Red Man Syndrome
41
The Effects of MRSA
42
MRSA
43
MRSA
44
The End
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