Staphylococcus aureus is a common cause of bacterial infections in children.  The most common "staph" infections are skin boils and abscesses.  Shortly after the development of penicillin-derivatives in the 1960's, some strains of Staphylococcus aureus were noted to be resistent to the effects of these antibiotics.  These "superbugs" were called methicillin-resistant Staphylococcus aureus (MRSA for short, which is often pronounced "mersa" or "mursa").  MRSA was originally seen only in hospital or nursing home patients, probably because of the widespread use of antibiotics in these settings.  In the 1990's, MRSA began to be noticed in patients without any known risk factors.  These infections are called "community-acquired" MRSA infections.  MRSA infections range in widely in severity.  Most MRSA infections occur as mild skin or soft tissue infections that respond well to drainage and/or certain antibiotics.

So what is the "SuperBug?"

Some strains of the common bacteria Staphylococcus aureus have developed resistance to certain antibiotics.  These "SuperBugs" have been called methicillin-resistant Staphylococcus aureus (MRSA) due to resistance to penicillin-class medications (i.e., methicillin) and other antibiotics (i.e., cephalosporins and others).

What make the "SuperBug" so super?

Staphylococcus aureus bacteria have a surface protein called "penicillin binding protein." This is where antibiotics (i.e., penicillin, methicillin, etc.) bind to the bacteria and prevent further construction of the bacterial wall.  Without the ability to build and maintain the bacterial cell wall, bacteria pop and die.  MRSA has developed the "super" ability to change the shape of the penicillin binding protein, making attachment of antibiotics less effective.

Another "superpower" of some MRSA strains is the ability to produce a chemical that is deadly to immune system cells such as monocytes, macrophages and neutrophils.

How common are MRSA infections?

Approximately 60% of skin and soft tissue infections seen in emergency departments in US hospitals are caused by MRSA.  Around 75% of "Staph" infections are caused by resistent strains of Staphylococcus aureus.

What kind of infections are caused by MRSA?

MRSA can infect almost any part of the body, but the great majority of MRSA infections are skin and soft tissue infections.  This includes:

• Boils
• "Risens"
• Abscesses
• "Pus pockets"
• Infected sores
• Cellulitis
• Folliculitis

Less commonly, MRSA can cause more serious illnesses such as pneumonia, joint infections, and bone infections. 

MRSA may cause life-threatening illness in some cases but this is uncommon.

How is MRSA diagnosed?

Most skin and soft tissue infections are easy to diagnose by a physician who is experienced with this diagnosis.  Skin infections are typically red, swollen, warm to touch, and painful.  Often, pus can be expressed out of a skin lesion or a pus collection can be felt under the skin.

To determine what is causing the infection, a sample of the the drained fluid or discharge can be sent to a laboratory for testing.  This is typically done by sampling the liquid with a sterile cotton swab.  This sample is sent to a laboratory where it can be placed on a culture dish to allow growth and identification of the bacteria.  Further testing can be done to determine what antibiotics are effective in treating the bacteria.  These bacterial "cultures" may take several days to get accurate results.

How is MRSA treated?

MRSA skin and soft tissue infections often need to be drained before treatment is effective.  Incision and drainage (I&D) is a method in which a medical person cuts open the wound to release the pus and bacteria.  Sometimes I&D is enough to cure the infection.  Antibiotics are often prescribed after I&D is performed.

Fortunately there are still antibiotics that kill MRSA bacteria.  There is ongoing concern that the superbug is getting smarter and that it is learning ways to resist even the strongest antibiotics.  Currently, common antibiotics like clindamycin (i.e., Cleocin) and trimethoprim/sulfamethoxazole (i.e., Bactrim, Septra) are able to treat most strains of MRSA effectively.

Why does my kid keep getting MRSA?

Children and adults can be "carriers" of the MRSA bacteria.  The bacteria often hides in your nose where it can be spread to other body areas when you rub your itchy nose and then scratch a bug bite or break in the skin.  MRSA can be eliminated from the nose with an antibiotic ointment applied within the nostrils for several days.

Dr. Tummy's view

MRSA skin infections are extremely common and are typically mild.  A typical emergency department (ER) or pediatric clinic sees several of these infections daily.

Photo 1 - CDC/ Janice Haney Carr/ Jeff Hageman, M.H.S.  2005.  Used with permission. Photo 2 - CDC/ Bruno Coignard, M.D.; Jeff Hageman, M.H.S. 2005.  Used with permission. Small photo - CDC/ Matthew J. Arduino, DRPH. 2001. Used with permission.