Download File - April D. Beresford, RN

Running head: EMERGING DISEASES
Emerging Infectious Diseases: Methcillin Resistant Staphylococcus Aureus (MRSA)
April D. Beresford
Ferris State University
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Running head: EMERGING DISEASES
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Abstract
The emergence and spread of methcillin-resistant Staphylococcus aureus (MRSA) has in the last
50 years grown to enormous proportions and has become one of the largest health concerns of
this decade. Despite attempts to control it with isolation techniques and treatment of active
infections with antibiotic therapy, it continues to spread and has become a threat not only to
hospitalized patients but to the community as a whole, on a worldwide scale. This article
explores the history and growth of MRSA from a standard strain of S. aureus to the superbug that
currently threatens us in and out of hospital settings, past and current treatment
recommendations, clinical presentations, global impact, treatment and prevention strategies.
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Introduction
Methcillin-resistant Staphylococcus aureus (MRSA) has become one of the most
widespread of all bacterial infections of this century, and has been identified globally. It is no
longer just a nosocomial infection, but is also identified in communities around the world.
MRSA and its progeny, vancomycin-resistant Staphylococcus aureus (VRSA), continue to
threaten the health and safety of world populations. Despite rigorous treatment and isolation
techniques, it is still responsible for illness and injury on a grand scale. As hospitals and
outpatient communities learn to cope with its spread, scientists are learning how it acquires
antibiotic immunity and are working to develop new antibiotics to treat MRSA infections.
Emergence
The bacteria we now refer to as MRSA was first identified in 1959. Since first becoming
resistant to penicillin, the bacteria has now evolved through five major lineage changes to
become resistant to more and more antibiotics (Robinson & Enright, 2003). Today it is evolving
again as it gains the ability to overcome vancomycin, which is of great concern because it is
currently the drug of choice to treat MRSA infections (Robinson & Enright, 2003) and this new
strain is being referred to as vancomycin-resistant staphylococcus aureus (VRSA). MRSA has
grown from a hospital-acquired infection to a community-oriented threat that has spread around
the globe (Robinson & Enright, 2003). Many reports exist detailing the struggle to contain it in
every continent, from Brazil to France, to Japan to the United States. In the United States alone,
MRSA isolates are found in 64% of invasive nosocomial infections (Martinez-Capolino et al,
2010), compared to only 2% in 1974 (Ko, 2011) necessitating a more aggressive approach at its
containment.
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Spread of Disease
According to Veenema (2013), “The emergence and spread of an infectious disease
requires the convergence of a diverse set of individual, social, and environmental factors.”
These factors are:

Microbial adaptation and change

Human susceptibility to infection

Climate and weather

Changing ecosystems

Human demographics and behavior

International travel and commerce

Technology and industry

Breakdown of public health measures

Poverty and social inequality

War and famine
Although the emergence of MRSA is multi-faceted, the factors that most associate with the
emergence and spread of MRSA are microbial adaptation and change, human susceptibility to
infection, human behavior, and international travel and commerce. MRSA is relatively
unaffected by climate changes as it is a highly adaptable bacterial strain. What was once almost
exclusively noted in hospital populations has transitioned into a large-scale community threat
(Boucher & Corey, 2008).
Microbial Adaptation and Change
“The overuse of antibiotics that decrease the bacterial flora can also affect the immune
system of even immunocompetant hosts, and contributes to the emergence of organisms resistant
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to treatment” (Veenema, 2013). The failure of antibiotics has lead to a higher disease burden
because there are fewer treatment options against active MRSA infections. Although the exact
origin of MRSA is unknown, methicillin was introduced to the market in 1959 to treat
Staphylococcus aureus that had become resistant to penicillin. In 1961 reports began to surface
that certain strains of Staphylococcus aureus had become resistant to methicillin. Physicians in
the United States in 2002 had documented the first emergent strains of VRSA, and physicians are
now left with fewer treatment options for infected patients. This is an example of the misuse and
overuse of antibiotics (NIAID, 2008).
Human Susceptibility to Infection
There are currently no vaccines available to prevent colonization with MRSA. Most
people who carry MRSA in their normal flora are healthy and show no signs of illness. Most
people find that they have MRSA when the bacteria begins to grow and infect some form of
injury or illness, such as a boil or a laceration. Like most bacteria, it thrives in moist, warm
environments and also finds the tissues in lungs and in blood and urine to make for fast growth.
MRSA is also zoonotic, meaning that is able to pass from animals to humans, and from humans
to animals. “Once exposed to MRSA, animals can become colonized, and may serve as
reservoirs to transmit the infection to other animals and also back to their human handlers”
(AVMA, 2013). The current prevalence of MRSA in animals is not yet known, but it has been
found in companion animals as well as animals raised for food production. In the United States,
45% of pig farmers tested were found to be carriers of MRSA (Ko, 2011). Despite that
connection, human-to-human transmission remains the most prevalent, and although everyone is
a potential carrier, those who are immunocompromised or work in healthcare facilities are at the
highest risk.
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International Travel and Commerce
Not long after MRSA was identified in England in 1961, it was found in Japan, Australia,
and the USA in 1968 (Enright, Robinson, Randle, Feil, Grundmann & Spratt, 2002). In 2004,
the United States was estimated to be the seventh most infected country for MRSA, behind
Romania (1), Malta (2), Argentina (3), Colombia (4), Brazil (5) and Cyprus (6). In the United
States, approximately 48% of all Staphylococcus aureus strains are drug-resistant (CDDEP,
2004). Global outbreaks have been reported in Saudi Arabia, Latin America, Asia, Western
Europe, India, Australia, New Zealand, and North America (Boucher & Corey, 2008).
Clinical Presentation and Identification
Skin infections with Staphylococus aureus often start as a small pimple or boil, and
quickly progress into deeper, more painful abscesses that may require surgical incision to drain.
Staphylococcus aureus is often part of a person’s normal flora, and remains inactive on the skin;
however, it can burrow deep and will replicate intensely in hospitable environments and can
cause life-threatening infections in the lungs, joints, bloodstream, heart valves, and in wounds
(Mayo, 2012). Diagnosis of MRSA is not made macroscopically, but rather by laboratory testing
of infected tissues or nasal secretions to differentiate MRSA from other bacterial invaders.
Traditional testing requires plating of the sample on a nutritional agar, but more modern methods
are becoming increasingly available, including a DNA testing method to identify MRSA (Mayo,
2012). Once identified, it is up to the provider to initiate treatment. If antibiotic therapy is
required, intravenous vancomycin is often the first line of treatment (Mayo, 2012).
The High Cost of MRSA
By recent estimation, MRSA has been responsible for about 19,000 deaths in the United
States annually, and 368,000 hospitalizations per year (Ko, 2011). In monetary terms, this adds
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up to a price tag of $3.2 billion to $4.2 billion annually, and MRSA patients are twice as likely to
die from an infection than non-resistant forms of S. aureus. Because MRSA has already
acquired resistance to several additional antibiotics, sufficient courses of treatment can be
financially costly (CDC, 2011). And anyone that has lost a family member to MRSA pays the
highest price of loss.
Prevention
Prevention for both forms of MRSA, hospital-acquired and community-acquired, are
relatively similar. Proper hand washing is of the utmost importance. When soap and water
washing is not possible, using a hand sanitizer with at least 62% alcohol is acceptable. Prompt
showering after exercise is recommended, as well as not sharing personal hygiene items such as
towels. Keeping cuts and scrapes properly covered is also important, as is not touching wounds
of other people without proper protective equipment. Washing of any contaminated clothing in
hot water with bleach when possible, and use of a hot-air clothing dryer will also prevent the
spread of bacteria (NIAID, 2008). Controlling risks, when possible, is also vital. Populations at
risk for community-acquired MRSA include those participating in group sports and those living
in crowded or unsanitary conditions. Populations at risk within the hospital setting include those
with invasive medical devices such as intravenous lies and urinary catheters or who are
endotracheally intubated, and patients who are admitted for long-term care in a healthcare
facility.
A debate exists between separating MRSA-infected patients from non-infected patients in
the healthcare setting if the MRSA infection is not active but the patient remains colonized.
Currently, Spectrum Health hospitals in southwest Michigan practice rigorous separation of
MRSA and non-MRSA patients in the admitted setting, as well as strict contact isolation
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precautions for all patients currently or previously infected with any form of drug-resistant
bacteria. In times of high census, cohorting of MRSA infected individuals is addressed on an
individual basis as long as the infection is not actively being treated, and based on the source of
the infection. Anytime this strategy is utilized, members of the infection control department are
notified and will evaluate each patient nominated for cohorting on a case-by-case basis taking
infection history and present infection risks into consideration. Because most transmission of
MRSA from patient to patient is thought to be mediated by transiently colonized healthcare
workers (Cooper et al, 2004), patients at Spectrum Health with a history of MRSA are treated
with contact isolation precautions. These precautions are in line with what current literature
suggests, and the current recommendation by the Center for Disease Control (2011). Going one
step further, in 2010 a study was finalized and published using data from a southeast Michigan
hospital using acute surveillance cultures to identify patients coming in to the hospital system
who were MRSA carriers. Unlike many hospitals that track only patients who have had previous
wound or sputum cultures that identified MRSA, these hospitals proactively screened every
patient. The hospital in the study who used the standard approach was identified as the control
group, and the other hospital utilized screening on all patients admitted to the intensive care unit
to definitively identify all occult carriers of MRSA. What this study demonstrated was that acute
surveillance cultures in addition to contact isolation precautions decreased ventilator-related
pneumonias as well as new diagnoses of nosocomial MRSA infections within the hospital
population (Martinez-Capolino et al, 2010).
In addition to active patient surveillance and managing carriers of MRSA in the inpatient
setting, rigorous room cleaning in the acute setting needs to be utilized. After a room has been
occupied by a MRSA patient, a terminal room clean needs to be implemented, and each and
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every item in the room that may have come into contact with the patient needs to be disinfected
(CDC, 2011). This is the policy of Spectrum Health in the inpatient setting, but is not currently
utilized in the emergency department, which puts patients at a certain risk for infection,
especially those that are immunocompromised. This has been a cause of concern by hospital
staff and patients, but currently there is no protocol for separation of the two populations.
Treatment
Because MRSA has already acquired resistance to additional antibiotics, including betalactams (penicillins and cephalosporins), fluoroquinolones (levofloxacin) and macrolides
(erythromycin and azithromycin) the current treatment recommendation is to use empirical or
oral forms of clindamycin, vancomycin, and daptomycin and these courses of treatment can be
costly (CDC, 2011). There are oral forms of some of these medications, but hospitalization is
often required initially to start a course of IV antibiotics. In the case of localized infections such
as abscesses and boils, the site may require surgical incision and draining. To determine the
most effective course of therapy, it is the current recommendation to justify antibiotic selection
by utilizing a culture and sensitivity test.
Conclusion
MRSA continues to threaten humans around the globe, and shows no signs of weakening.
It has the potential to cause global devastation as it evolves to acquire additional antibiotic
immunities. As physicians continue to struggle to effectively treat this superbug, emphasis needs
to be placed on prevention at both the personal level and in acute healthcare settings.
Knowledge of risk factors as well as forms of transmission is important. MRSA is costly, both
in terms of financial relations as well as personal illness and death. With MRSA indefinitely part
of our future, as healthcare providers we must do what we are able to slow its progression.
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References
American Veterinary Medical Association [AVMA] (2013). MRSA and animals. Retrieved Feb.
23, 2013 from https://www.avma.org/KB/Resources/FAQs/Pages/MRSA-HHPFAQs.aspx
Boucher H, Corey R (2008). Epidemiology of methicillin-resistant Staphylococcus aureus.
Journal of Clinical Infectious Disease, 46(5), pp. 344-349.
Center for Disease Control (CDC) (2011). Preventing the spread of MRSA in healthcare settings.
Retrieved March 7, 2013 from http://www.cdc.gov/mrsa/prevent/healthcare.html
Center for Disease Dynamics, Economics and Policy [CDDEP] (2004). MRSA infection rates by
country. Retrieved Feb. 23, 2013 from
http://www.cddep.org/tools/methicillin_resistant_staphylococcus_aureus_infection_rates
_united_states_and_other_countries
Cooper B, Stone S, Kibbler C, Cookson B, Roberts J, Medley G, Duckworth G, & Ebrahim S
(2004). Isolation measures in the hospital management of methicillin-resistant
Staphylococcus aureus (MRSA): a systematic review of the literature. Biomedical
Journal (BMJ), doi: http://dx.doi.org/10.1136/bmj.329.7465.533
Enright M, Robinson DA, Gaynor R, Feil E, Grundmann H, Spratt B (2002). The evolutionary
history of methicillin-resistant staphylococcus aureus (MRSA). Proceedings of the
National Academy of Sciences of the United States of America. 99(11), doi:
10.1073/pnas.122108599
Ko, L. (May 2011). MRSA: The superbug. Public Broadcasting System (PBS). Retrieved from
http://www.pbs.org/wnet/need-to-know/five-things/mrsa-the-superbug/9412/
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Martinez-Capolino C, Reyes K, Johnson L, Sullivan L, Samuel L, DiGiovine B, Eichenhorn M,
Horst HM, Varelas P, Mickey MA, Washborn R, & Zervos M. (2010). Impact of active
surveillance on methicillin-resistant Staphylococcus aureus transmission and hospital
resource utilization. Journal of Hospital Infection, 74(1).
Mayo Clinic (2012). MRSA: risk factors. Retrieved Feb. 23, 2013 from
http://www.mayoclinic.com/health/mrsa/DS00735/DSECTION=risk-factors
National Institute of Allergy and Infectious Disease [NIAID] (2008). Methcillin-resistant
Staphylococcus aureus (MRSA) history. Retrieved Feb. 23, 2013 from
http://www.niaid.nih.gov/topics/antimicrobialresistance/examples/mrsa/pages/history.asp
Robinson D, Enright M (2003). Evolutionary models of the emergence of methicillin-resistant
staphylococcus aureus. Antimicrobial Agents and Chemotherapy, 47(12), pp.3296-3934.