Methicillin-resistant Staphylococcus Aureus (MRSA) in the Community Setting

By M. C. Thirumoorthi, M.D., Pediatric Infectious Diseases, St. John Hospital and Medical Center

Question: Everywhere you turn, people are talking about MRSA. I hear conflicting reports about the risks involved. Some schools are closing but others, like Grosse Pointe South, are not. Do you have someone who can clarify this?

Answer: MRSA (usually pronounced Mir-suh) has been in the news a lot lately, both nationally and in our community. A great variety of concerns (both justified and exaggerated) have arisen in relation to this bacterial germ.


Staphylococcus aureus (often simply called ‘staph’) has always been a common cause of infections of the skin and related structures. It also causes some serious diseases such as blood stream infections and bone infections. Before the availability of antibiotics it was an important cause of wound infections that often lead to complications and death.

A dramatic change in outcome from these infections occurred when penicillin became available in the 1940s. However staph strains resistant to penicillin emerged fairly quickly and, by the 1980s, penicillin became ineffective. New drugs such as methicillin were discovered that were effective against penicillin resistant staph.

Over the next few years staph strains began to show resistance to methicillin and to drugs similar to methicillin. (These resistant strains of staph were called MRSA. Even though methicillin has been almost completely replaced by related drugs, the term MRSA is still the most common term used to refer to this type of staph). Initially (beginning in the 1980s) MRSA was primarily a problem in hospitals and other health care settings.

However, in the late 1990s this began to change. MRSA began to cause infections even among people who had no exposure to healthcare settings. These strains (clans) of MRSA were called community-associated MRSA or CA-MRSA, and have become responsible for an increasing fraction (sometimes exceeding half) of the community-associated staph infections. There are differences between strains of healthcare-associated and community-associated staph but each of these two types can be found to cause infections in both settings.

Only a few of us experience staph infections but a lot of us (up to 25% of the population) are colonized (when bacteria are present, but not causing an infection) in our noses with this germ. About 1% of the overall population is colonized with MRSA.

Staph infections can range in severity ranging from a small pimple or boil to wound infections to life-threatening infections in the lung (pneumonia) and in the blood stream. Many strains of MRSA produce various toxins that increase the severity of the disease caused by this bacterium. Also debilitation and other factors that affect the immune status of an individual increase the severity of the disease caused by MRSA.

Some factors that increase the likelihood of the spread of and subsequent disease due to MRSA include close skin-to-skin contact (for example, athletes such as wrestlers), openings in the skin such as cuts or abrasions, contaminated items and surfaces, crowded living conditions, and poor hygiene.

When skin infections occur, depending on the severity of the infection, culturing the wound drainage provides information on the nature of the infection. Drainage of the lesion may be the only treatment necessary in some instances. In others treatment with an appropriate antibiotic (with or without drainage of the pus) will be necessary. In all instances it is important to keep in mind the possibility that the infection may spread locally or to other parts of the body. Such awareness will allow for early reevaluation and interventions such as hospitalization, intravenous antibiotics and surgery when needed.

The single most important element in the prevention of these infections is practicing good hygiene. These measures include keeping our hands clean by washing thoroughly with soap and water or using an alcohol-based hand sanitizer, keeping cuts and scrapes clean and covered with a bandage until healed, avoiding contact with other people’s wounds or bandages and avoiding sharing personal items such as towels or razors. In the setting of schools, gyms and athletic activities these measures are equally important.

In some instances individuals get multiple (recurrent) episodes of MRSA infections or multiple members of a family or activity group get concurrent or sequential infections. Early recognition and treatment of these infections is important. .The hygienic measures mentioned above are helpful in minimizing the spread of the germ in these settings. Often decontamination measures such as the use of antibacterial nasal creams, washing with antiseptic or diluted bleach solution are recommended. However the effectiveness of these measures has not been critically studied. In community settings, the role of widespread decontamination efforts is of questionable benefit even if our fears and anxieties lead us to adopt these measures.

The website of the Centers for Disease Control (CDC) at www.cdc.gov is a good and reliable source of useful information on MRSA http://www.cdc.gov/DiseasesConditions/ as well as on many other diseases.

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