Dental updates from Dr. Mckeever.

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Antibiotic overuse - "toxic megacolon"

As most of you probably know, the overuse of antibiotics for all sorts of maladies has resulted in the gowth of "super bugs" many of which are no longer affected by these drugs. The most familiar one in these times is the MRSA strain of bacteria which is a Stephylococcus aureus that is on our skin but can turn lethal if it gets into our system through a cut or scrape; we are running out of options for antibiotics that can kill this germ. And, there are others not as familiar.

Because dentists frequently give patients antibiotics for oral infections, we must be aware of adverse consequences. We also use them in patients with certain heart problems to prevent the possibility of contracting bacterial endocarditis (SBE) an infection of the heart valves that have defects. (Recently, the American Heart Association finally announced that most patients that here-to-for had to take antibiotics before invasive medical or dental procedures no longer needed to do so. The rationale is that there hasn't ever been a documented case of a patient acquiring SBE from a medical or dental procedure and that takling antibiotics to prevent SBE was much more likely to cause problems that any remote possiblility of contracting an infection!

Unfortunately, I have had two patients (that I know of) who experienced a life threatening reaction to antiobiotic therapy prescribed by me. This was extremely disturbing even though no one can predict such occurrances. The germ involved in most of these cases is the Clostridium difficile strain of bacteria and the resulting infection of the intestine is called "toxic megacolon" (CDAD). Over the last 10 years, the number of patients hospitalized as a result of CDAD in the U.S. has risen sharply doubling in occurrance per 100,000 population. Also, the severity has increased with more cases requiring surgery or more patients dying. Patients older than 60 years are four to five times more likely to contract the disease and are at an increased risk of dying from the disease.

C. difficile is spread by the fecal-oral route but how that happens is pretty much anybody's guess. After ingestion, the spore form germinate into a vegetative form in the small intestines and eventually colonize the mucosal crypts of the large intestine. They then proliferate when the normal bacterial colonies in the intestines are disrupted; the most common event that causes this disruption is through the use of antibiotics! A 2004 study addressed the role of this germ in the food supply most specifically in the consumption of particular meats. Other risk factors associated with acquiring C. difficile is long hospital stays, especially in long-term care facilities, nasogastric intubations and, perhaps, even taking anti-ulcer medications called "proton pump inhibitors" (although there is no consensus in their role in this disease).
Like other strains of the Clostridium species ( C. tetani {tetanus} and C. perfrigins {gangrene}), it is the toxins from the spore-forming bacteria that cause the disease and diagnosis is made by detecting the toxin from stool specimens.

The antibiotics most associated with causing CDAD are the cephalosporins, penicillins and clindomycin. (Unfortunately, these are the best medications for pulpal infections of the teeth). These antibiotics upset the natural balance of "good bacteria" that normally reside in the intestines. Cessation of the offending antibiotic, if possible, allows the bowel to repopulate with normal bacteria and, thus, limit the impact of the infection in a natural fashion. The ingestion of a probiotic food while on antibiotics can greatly reduce the chances intestinal problems of any kind! The British Medical Journal in their July, 2007, issue reported that patients that used a probiotic drink (DanActive) starting two day before, during and up to one week after antibiotic therapy reduced the incidence of diarrhea associated with antibiotic therapy. Of those who used the probiotic drink, only 12% had any intestinal distress v.s. 34% of those who ingested a placebo drink. Any probiotic food (I recommend eating yogurt to all of my patients on antibiotics) that contain the beneficial bacterial species Lactobacillus casei, L. bulgaricus and Streptococcus thermophilus can be used. These are listed on the labels of all yogurt tubs (along with several other bacterial species).
posted by Steve at 2:52 PM