Dental antibiotics – When to use what
Cephalosporins don’t offer any advantage over penicillin V unless the patient is in the hospital. Cephalosporins are effective against S aureus, an organism responsible for many secondary infections that patients acquire in hospitals. For penicillin-allergic patients, the antibiotic of choice is clindamycin. If allergic to both then see below. Macrolides, such as erythromycin and azithromycin, have no place in the treatment of odontogenic infections and have the potential to cause significant harm. Tetracyclines, although effective for the treatment of some periodontal infections, are not indicated in the treatment of patients with infections of odontogenic origin.
If the source of the infection has been removed and the patient fails to respond favorably after two to three days of penicillin V or clindamycin therapy, it is necessary to add metronidazole. Metronidazole is highly effective against anaerobic bacteria but inactive against obligate aerobes, thus it is a good antibiotic for sinus graft infections. Therefore, it is not appropriate as a first line of defense or replacement antibiotic for infections of odontogenic origin, but is very effective in combination with the primary antibiotic of choice.
The recommended dental antibiotic dosages are as follows:
- Penicillin V: 500mg QID
- Amoxicillin: 500mg TID
- Clindamycin: 300mg TID or QID
- Metronidazole: 500mg TID or QID
What to do when a patient is allergic to both penicillin and clindamycin?
- Azithromycin Z-Pack 3 or 5 day pack
- Clarithromycin 500mg (2 tabs for premed) 250-500mg q 12hr 7-14 day
- Erythromycin 500 mg (2 tabs for premed) 250-500mg q6-12hr 7 day
Should patients take the full does of antibiotics?
The dosage and time lines are arbitrary and best guesses more than anything that comes from solid research. Add in the fact that every infection and individual is different and that the bacteria is mutating means IMHO the guidelines are not terribly useful. The AAE put out a very nice dental antibiotics myths. I especially like the following two myths,
- Myth #7: Antibiotic dosages, dosing intervals and duration of therapy are established for most infections.
- Myth #8: Bacterial infections require a “complete course” of antibiotic therapy.
Another article from Discover Oct 2014 issue that lists plenty of research showing that it is likely NOT the best advice to take all antibiotics.
What if a patient is already taking an antibiotic and requires a prophylactic antibiotic?
“Another concern that dentists have expressed involves patients who require prophylaxis but are already taking antibiotics for another condition. In these cases, the recommendations for infective endocarditis recommend that the dentist select an antibiotic from a different class than the one the patient is already taking. For example, if the patient is taking amoxicillin, the dentist should select clindamycin, azithromycin or clarithromycin for prophylaxis.” From this post on antibiotic prophylaxis recommendations.