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What is MRSA?
MRSA is a type of Staphylococcus aureus (S. aureus).
Staphylococcus aureus, often referred to simply as “staph,” are
bacteria commonly carried on the skin or in the nose of healthy people.
Some S. aureus are resistant to the class of antibiotics that are
frequently used to treat staph such as methicillin—and thus are called
methicillin-resistant S. aureus(MRSA).
Who gets MRSA?
S. aureus
(staph) including MRSA can be spread among people having close contact
with infected people. MRSA is almost always spread by direct physical
contact and not through the air. Spread may also occur through indirect
contact by touching objects (e.g., towels, sheets, wound dressings,
clothes, workout areas, or sports equipment) contaminated by the infected
skin of a person with staph bacteria or MRSA.
Just as S. aureus can be carried on the skin or in the nose without
causing any disease, MRSA can be carried in this way also. This is known
as colonization.
MRSA infections are usually mild, superficial infections of the skin that
can be treated successfully with proper skin care and antibiotics. MRSA,
however, can be difficult to treat and can progress to life-threatening
blood or bone infections because there are fewer effective antibiotics
available for treatment.
MRSA infections occur commonly among persons in hospitals and healthcare
facilities. However, MRSA can cause illness in persons outside of
hospitals and healthcare facilities as well. Cases of MRSA infection in
the community have been associated with recent antibiotic use, sharing
contaminated items, having recurrent skin diseases, and living in crowded
settings. Clusters of skin infections caused by MRSA have been described
among injecting drug-users (1,2); aboriginals in Canada (3), New Zealand
(4) and Australia (5,6); Native Americans in the United States (7);
incarcerated persons (8); players of close-contact sports (9,10); men who
have sex with men (MSM); and other populations (11-17). Most of the
transmission in these settings appeared to be from people with active MRSA
skin infections.
How
do I know if I got MRSA from the community or from a healthcare setting?
Persons with MRSA infections that
meet all of the following criteria likely have community-associated MRSA
(CA-MRSA)
If my doctor or healthcare
provider has told me that I have an MRSA skin infection, what can I do to
prevent others from getting infected?
You can prevent spreading an MRSA infection to those you
live with or others around you by following these steps:Keep infections,
particularly those that continue to produce pus or to drain material,
covered with clean, dry bandages. Follow your healthcare provider’s
instructions on proper care of the wound. Pus from infected wounds can
contain MRSA and spread the bacteria to others. Advise your family and
other close contacts to wash their hands frequently with soap and warm
water, especially if they change your bandages or touch the infected wound
or potentially infectious materials. Avoid sharing personal items (e.g.,
towels, washcloth, razor, clothing, or uniforms) that may have had contact
with the infected wound and potentially infectious material. Wash linens
and clothes that become soiled with hot water and laundry detergent.
Drying clothes in a hot dryer, rather than air-drying, also helps kill
bacteria in clothes. Tell any healthcare providers who treat you that you
have an antibiotic-resistant staph skin infection.
How is MRSA diagnosed?
A sample of the infected wound (either a small biopsy of
skin or pus taken with a swab) must be obtained to grow the bacteria in
the microbiology laboratory. Once the staph is growing, the organism is
tested to determine which antibiotics will be effective for treating the
infection. A culture of skin lesions is especially useful in recurrent or
persistent cases of skin infection, in cases of antibiotic failure, and in
cases that present with advanced or aggressive infections.
What is the mortality rate of
CA-MRSA?
CA-MRSA infections are typically limited to the skin and do
not result in severe disease (such as infection of the bloodstream) or
death. However, on rare occasion, CA-MRSA can cause severe illness even
when treated quickly, as in the cases of four children who died from
CA-MRSA (18).
Does CDC think CA-MRSA should be reportable?
The decision to make a particular disease reportable to
public health authorities is made by each state based on the needs of that
individual state. CDC supports the resolutions passed by the Council of
State and Territorial Epidemiologists (CSTE) in May 2003. For more
information on CSTE resolutions regarding MRSA go to: www.cste.org
I have heard this bacterium is attacking healthy people
and healthy skin. Is this what CDC is seeing?
Yes, staph infections commonly affect healthy people and
healthy skin. Usually, these infections are easily treated. Any activity
that promotes breakdown in skin integrity (e.g., chronic skin infections,
physical trauma, poor health) can promote staph skin infections including
those caused by MRSA.
 Are
people who are positive for the human immune
deficiency virus (HIV) at increased risk for MRSA? Should they be taking
special precautions?
People with increased exposure to antibiotics and the
healthcare setting may be at increased risk for antibiotic-resistant
infections of various kinds, including MRSA. People with compromised
immune systems, which include some patients with HIV, may be at risk for
more severe illness if they get infected with MRSA.
Why does CDC think so many cases of MRSA are being
recognized across the country?
MRSA has been recognized as a problem in the healthcare
setting for over 20 years. CDC believes that MRSA has been emerging in the
community over the last several years. It is difficult to determine
whether there is an increase in MRSA disease in the community or an
increased awareness and recognition of MRSA disease. However, it is clear
that some of the recently recognized outbreaks of CA-MRSA are associated
with strains that have some unique properties compared to the traditional
hospital-based MRSA strains, suggesting some biologic properties (like
virulence factors) may allow the CA-MRSA strains to spread more or cause
more disease; however, these hypothesis need testing and confirmation.
Are all the cases of CA-MRSA in
the U.S caused by the same strain of staph? Are these cases all related?
At present, there appears to be at least three different
strains of staphylococci that can cause CA-MRSA infections in the United
States. CDC continues to work with state health departments to gather both
the organisms and epidemiologic data from all the cases reported in the
medical media to determine why certain groups of people get infections
with these organisms. Efforts to evaluate staphylococci from around the
U.S. are ongoing.
What is CDC doing about CA-MRSA?
Public Health Response
- CDC is providing technical assistance
to various professional organizations and state health departments to
develop guidance for control of MRSA.
- CDC is beginning a national
program of surveillance for serious infections with MRSA.
Prevention Activities
Surveillance and epidemiologic
studies in community populations
- In 2000, CDC began working closely
with four states, with a combined population of about 12 million
persons, to study the epidemiology of CA-MRSA infections. The
information from these studies is helping CDC understand the nature of
the disease, why people get infected, and to develop future studies
designed to improve our ability to prevent these infections. These
data are being collected in Connecticut, Minnesota, Georgia, and
Maryland as part of CDC's Emerging Infections Program, Active
Bacterial Core surveillance (ABCs). This program is being expanded
to six states in 2004.
- In addition to enhancing our detection
of MRSA cases in healthcare settings by adding a module to CDC's
National Healthcare Safety Network, we are working with
representatives of state health departments to augment a national
surveillance program for invasive MRSA, including CA-MRSA
infections.CDC is using data collected in outbreak investigations in
correctional facilities, in athletic teams, in children, in MSM and
from sporadic cases to learn about strain characteristics, risk
factors for disease, and prevention measures and to provide clinical
education about CA-MRSA. Some of this information has been published
in the MMWR. Findings from investigations in various settings will be
published in peer-reviewed literature and the MMWR over the next year.
- Representatives from 40 states
and territories participated in a March 2003 meeting on enhancing
state-based reporting of MRSA. CDC is working with states that are
interested in initiating or expanding surveillance of MRSA (both CA-
and healthcare-associated MRSA) in their states.
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