There’s an E.R. Doc in my town that has been trying to alter (interfere) with a dental standard of practise. His view that Clindamycin should never be prescribed because of its link to pseudomembranous colitis is shared by many physicians. The infections that they commonly see are generally treatable by other antibiotics and so these physicians are usually able to prescribe viable alternatives to Clinda. If they are hospital-based, they also often have the luxury of being able to order and obtain results of culture and sensitivity tests quickly. They figure if they can find alternatives, dentists should also.

Pseudomembranous Colitis is a severe case of (often bloody) diarrhea. The diarrhea is a result of alterations between the balance of “good” bacteria and “bad” bacteria in the colon. Bacteria exist in all of our intestines and live within this equilibrium. The good bacteria help with some digestive processes and also some pharmacologic processes–the birth control pill relies on good bacteria to help its components get absorbed into the body.

Antibiotics either kill bacteria or stop their proliferation. Most antibiotics will significantly alter the proportion of good bacteria in the intestine. This can lead to failure of oral contraception, or as related to this topic, overgrowth of the bad bacteria.

Clostridium Difficile is a common problem in nursing homes and hospitals because of the population of immuno-compromised patients and the fact that this bacterium can be resistant to antibiotics. It is also generally considered the cause of antibiotic-induced pseudomembranous colitis. Overgrowth of this bacterium in the gut produces toxins that lead to bloody diarrhea. Persistent diarrhea that appears for no obvious reason during antibiotic therapy even up to six weeks after cessation of antibiotics can indicate that you have the condition.

Treatment for the diarrhea is the antibiotic Metronidazole, or in resistant cases, Vancomycin. It is interesting to note that Metronidazole itself can cause pseudomembranous colitis, yet it is also a treatment. As long as Metronidazole wasn’t responsible for the original bacterial imbalance, it should be effective at bringing C. Difficile levels back down.

Dental infections have been shown to be polymicrobial in nature and fuel cariogenesis, periodontal, and endodontic pathosis. Endodontic infection is the number one reason for the emergency use of antibiotics in dentistry.

Decades of microbiologic testing have found that certain species of bacteria turn up again and again in endodontic infections. Susceptibility testing by Baumgartner found that Amoxicillin (combined with Clavulinic acid) was 100% effective at killing bacteria within his study sample. Clindamycin was second at 96%¹.

In addition, there is evidence that is suggestive that teeth which have had root canal treatment in the past, and that are either recurrently or persistently infected, contain bacteria that might be better treated with Clindamycin².

With all of this taken into consideration, it is reasonable to assume that dentists will need to prescribe a significant amount of Clindamycin to control tooth abscesses. A good number of patients’ charts in my office have little stickers indicating Penicillin allergy (Amoxicillin is a type of Penicillin). This then leaves Clindamycin as the next logical choice.

To finish up, here’s the final important fact: Both Amoxicillin and Clindamycin (among other antibiotics) have been shown to contribute to the risk of developing Pseudomembranous Colitis.

With the amount of dental infection out there, we have to assume that there’s a lot of Amoxicillin and Clindamycin being prescribed by dentists. For argument sake, say the incidence of Clinda-induced colitis is 1% and there are 1000 prescriptions a week for Clinda. Ten patients a week would have some sort of diarrhea within 6 weeks of taking the antibiotic. An E.R. department would probably not see all of these patients, but they would sure see a good number of them. This then reinforces within the mind of this particular E.R. Doc, of whom I am writing, that Clinda is bad–very bad. I’m sure he doesn’t ask patients if they’ve been taking any other antibiotics, and if he does, he doesn’t realise the link these antibiotics might have to the diarrhea. He just attributes the diarrhea to something else less obvious.

This particular MD vehemently informs patients that the dentist is at fault for giving them Clindamycin and encourages them to seek further action against the dentist. This type of behaviour is unprofessional, has gone on long enough, and is going to result in action on my part.

As an aside; I recently retreated a root canal on a patient who is the husband of a physician in town. He flared up between appointments, so I prescribed Clinda for him. His wife refused to let him take the antibiotic because they had a patient once who got colitis from it. So she gave him something else (probably Clarithromycin) and the infection got worse while he was taking this other antibiotic. A week later, he was no better off. They reconsidered their choice at that time.

1. Baumgartner JC, Xia T. Antibiotic susceptibility of bacteria associated with endodontic abscesses. J Endod. 2003 Jan;29(1):44-7. [↩]
2. Molander A, Reit C, Dahlen G, Kvist T. Microbiological status of root-filled teeth with apical periodontitis. Int Endod J. 1998 Jan;31(1):1-7. [↩]