MRSA- A Lesson in Evolutionary Biology

Methicillin-resistant Staphylococcus aureus (MRSA) simply refers to the development of antibiotic resistance by a common skin bacteria over the last several decades.

"If it bleeds, it leads" news coverage to the contrary, MRSA is not new, not invariably fatal and not incurable or untreatable.

Staph (as Staphylococcus aureus) is commonly known, is one of the common bacteria found in the environment and on any normal, healthy person's skin. Because it is always on your skin, it is one of the most common bacteria to cause skin infection when you get a scrape, cut or some other break in the skin's surface.

Antibiotics used to treat skin infections can lead to the development of antibiotic resistance in surviving strains Staph. Slowly and steadily over the past few decades, strains that resist common antibiotics have become more and more common. This is an expected evolutionary result of antibiotic use.

At this point, MRSA has become a common cause of skin infections. Fortunately, many antibiotics that are inexpensive, safe and generically available work against MRSA (such as Bactrim and Cleocin). This does mean that if doctors suspect MRSA, they may want to use these instead of the usual ones like Keflex or Amoxicillin.

Otherwise, it is not unusual for normal healthy people to spontaneously carry MRSA, and to also spontaneously stop carrying it. Eradication of MRSA from your home and body is technically possible, but really not practical (industrial-strength showers three times a day for a month, anyone?).

Do I Need Antibiotics Before I Get My Teeth Cleaned?

Short answer: For most patients, probably not.

Long answer:

The American Heart Association has been refining recommendations on who should take antibiotics before certain kinds of surgeries or procedures for about 50 years.

Revisions to prior recommendations were made last year. Factors that weighed into these new recommendations included existing evidence, recognition that bacteria entering the bloodstream occurs with normal daily activity, and the awareness that antibiotic use itself is not without risk.

Who may need antibiotics for dental visits? Those with conditions of highest risk for heart infections as a result. These would be folks who (1) have had heart infections before (Infectious Endocarditis), (2) those who have artificial heart valves or heart valve repairs using artificial materials, (3) those who had a heart transplant and then developed heart valve problems, and (4) those who were born with structural heart problems (Congenital Heart Disease) which were not repaired, or were repaired with artificial materials.

What kind of dental visit needs antibiotics? This would really depend on what your dentist plans to do.

What antibiotics should be used? Amoxicillin is the best choice, though there are several alternatives if you allergic to it. The antibiotics should be taken 30-60 minutes before hand, though could be taken for up to 2 hours after the work.


PLEASE NOTE:

We will work in conjunction with your dentist to identify whether you fit into one of the four high-risk groups described above.

However, only your dentist knows whether what they plan to do will make antibiotic treatment beforehand advisable or not. That decision needs to be made by them.

Peter Lockhart, DDS, Chair of Oral Medicine at Carolinas Medical Center is a member of the committee that wrote these new recommendations, and comments that:

"the primary care physician’s responsibility is to determine whether the patient has one of the four qualifying cardiac conditions. If the patient has one of those conditions, it’s the dentist’s responsibility — not the physician’s — to determine whether the upcoming dental procedure warrants prophylaxis."