The most common infections of the oral cavity can be attributed to resident oral microflora, namely Streptococcus and Staphylococcus species (gram positive bacteria). Oral infections may occur as tooth infections, pharyngeal infections, as post-surgical complications, or as unusual infections due to a patient’s immunocompromised status. When choosing an antibiotic, the dental provider must choose an antibiotic that targets the suspected microorganism, has low host toxicity, has low host sensitivity, is bacteriocidal, and has low resistance potential, all with a minimum of side effects to the patient.
Indications/Contraindications for antibiotic therapy
Antibiotics may be prescribed when all of the following conditions are met:
The patient presents to one of the service unit dental facilities or has previously been diagnosed by a service unit dentist with an oral infection (within the past month);
The dentist performs diagnostic tests to confirm a diagnosis of an abscess or cellulitis, to include at a minimum a clinical examination and radiographs or pulp testing if possible; or in the absence of a dentist on site, a medical provider performing diagnostic testing to confirm a diagnosis of oral infection;
The patient record contains an updated health history (either medical or dental forms) that details any allergies that the patient may have had in the past.
Antibiotics may not be prescribed under the following conditions:
The patient does not present (show up) to the service unit dental or medical facility, and where there is no documentation to support antibiotic therapy (in other words, the dentist is precluded from making diagnoses by triaging the patient over the phone without a sufficient documented history of infection).
The patient presents to the clinic but the dentist (or in his/her absence, the medical provider) cannot make a definitive diagnosis of an oral infection based on the available clinical evidence (for example, if the patient is afebrile and diagnostic tests are negative).
The patient record does not contain an up-to-date health history (within the past year).
Characteristics of common antibiotics
Because most oral infections are caused by resident gram positive bacteria, a broad spectrum antibiotic that targets gram positive bacteria should be prescribed in most situations.
Penicillin V with potassium (Pen VK) is THE drug of choice for most facial infections, according to the Centers for Disease Control and Prevention. Penicillin V is bactericidal, is acid stable (isn’t broken down easily by gastric acid), and is beta lactamase labile. Although the chemical composition of Penicillin V contains sulfur, it is safe to prescribe Pen V to patients with sulfur allergy as the sulfur is in elemental form. When prescribing penicillin, it is very important to have the patient take the antiobiotic on an empty stomach if possible to increase a rapid absorption, even though many pharmacists will encourage patients to take the antibiotics with food or water. In addition, Pen V should be prescribed in a manner to give the patient a maximum load at the beginning of therapy, and, since 75% of penicillin is excreted in the first four hours, patients should be encouraged to take the antibiotic every six hours, not simply four times daily – if the patient takes the antibiotic q.i.d., and takes the antibiotic at mealtimes only, two things will happen: absorption of Pen V will be delayed due to taking it with food, and there will be no antibiotic coverage late in the evening (if the patient takes the last tablet at 9 p.m., for example, the patient would not have antibiotic coverage from 1 a.m. the next morning until they take the next tablet). Therefore, the prescription for Penicillin V would appear as:
Rx: Penicillin V-K, 500 mg tablets
Disp: 30 tablets
Sig: Take two tablets to start, then one tablet every six hours until all tablets are gone
Penicillin is contraindicated in those patients that report a history of an allergic reaction to it.
Amoxicillin is a penicillin antiobiotic that is bacericidal, is of a broader spectrum than Penicillin V, is acide stable, and beta lactamase labile. It is not the drug of choice for most oral infections, although most dentists try to use it in this way. However, amoxillin is the preferable regimen for prophylaxis for subacute bacterial endocarditis (SBE), according to the American Heart Association. The SBE prophylaxis prescription for amoxillin would appear as:
Rx: Amoxicillin, 500 mg tablets
Disp: 4 tablets
Sig: Take four tablets one hour before dental appointment
For SBE prophylaxis, the AHA states that prophylactic antibiotics be taken one hour before a dental appointment. Dentists and pharmacists have questioned whether this time frame can be changed to say, 30 minutes. However, in the absence of clear, written guidance from the AHA or CDC regarding this, the dental provider must adhere to the one-hour timeline before any procedures are begun.
What should be done when a patient does not respond to Pen V? Often, dentists immediately prescribe another class of antibiotics. However, two other choices are more appropriate if the patient does not respond to Pen V within 48 hours. First, the dentist may prescribe 875 or 1000 mg Augmentin (every 12 hours). Augmentin is also acid stable and bactericidal, is a broad spectrum antibiotic, and is a combination of amoxicillin and clavulanic acid. Secondly, the dentist may prescribe 500 Penicillin V plus a broad-spectrum antibiotic such as Flagyl (metronidazole). However, the dentist should be mindful of the potential adverse effects of Flagyl (see Metronidazole section).
Cephalosporin antibiotics are bactericidal, broad spectrum, acid stable, and beta lactamase stable or labile (depending on cross-sensitivity with penicillin), but are NOT preferable antibiotics for oral infections. For patients with sensitivity to penicillin, 6-8% of those patients may have a delayed reaction to the cephalosporins (if the patient reported that they had a history of a “mild” reaction to penicillin), but >20% of the patients may have a Type I reaction (anaphylaxis) if they reported a similar Type I reaction to penicillin in the past. Therefore, the dentist should refrain from using cephalosporin antibiotics as an alternative to penicillin due to penicillin sensitivity. However, if the dentist does wish to prescribe a cephalosporin, a first generation cephalosporin (Keflex, Duricef) should be prescribed, such as an alternative to penicillin for SBE prophylaxis, the prescriptioon should be written such as follows:
Rx: Cephalexin, 500 mg tablets
Disp: 4 tablets
Sig: Take four tablets by mouth one hour before dental appointment
Bottom line: If a patient is allergic to penicillin, the dentist shouldn’t even attempt to prescribe cephalosporin, and should prescribe clindamycin as an alternative instead.
Erythromycin (Ery-tab) has no use in dentistry at all, according to Dr. Harold Crossley from the University of Maryland Dental School. Additionally, erythromycin is NOT one of the alternative antibiotics that can be used for SBE prophylaxis.
Clindamycin (Cleocin) is bacteriostatic and bacteriocidal, is acid stable, and is a broad spectrum antibiotic. One published adverse effect of clindamycin is pseudomembranous colitis (PMC)/ulcerative colitis. Approximately 80% of PMC cases are nosocomial, and patients are at very low risk of having this side effect in a dental setting. However, if a patient reports diarrhea after starting clindamycin therapy, the dental provider should tell the patient to immediately cease taking the antibiotic, and if the diarrhea or GI symptoms continue (for 72 hours), the dentist should refer the patient to a physician (internist) for follow-up care. Clindamycin is the drug of choice for patients allergic to penicillin, and should be written as follows:
Rx: Clindamycin, 300 mg capsules
Disp: 16 capsules (or 32 if 150 mg capsules are prescribed)
Sig: Take 2 (4) capsules to start, and then one capsule (2) every 12 hours for seven days
The dentist may prescribe clindamycin for SBE prophylaxis as follows:
Rx: Clindamycin, 300 mg capsules
Disp: 2 capsules
Sig: Take 2 capsules one hour before dental appointment
Azithromycin is an extended spectrum antibiotic that can be used as an alternative regimen for SBE prophylaxis as follows:
Rx: Azithromycin, 250 mg tablets
Disp: 2 tablets
Sig: Take 2 tablets one hour before dental appointment
Tetracyclines are broad-spectrum bacteriostatic antibiotics that target gram positive and gram-negative bacterial infections. However, due to the many adverse reactions possible with tetracyclines, they should not be routinely be used for most oral infections. Adverse reactions possible include gastointestinal distress and nausea, hepatic and renal toxicity, tetragenecity in pregnant women, the possibility of superinfections such as candidiasis, and photosensitivity (even in subtherapeutic doses). Due to the GI problems, which may be as severe as esophagitis, patients receiving tetracyclines should drink lots of water when taking the antibiotic. Tetracycline is contraindicated for patients with orthopedic prostheses, and are contraindicated for patients taking penicillin (for example, if an adolescent is taking a tetracylcline for acne, the dentist should not prescribe a penicillin for that patient, but rather clindamycin). Tetracyclines are also contraindicated for patients on oral anticoagulant therapy (coumadin), and patients prescribed tetracycline in any dosage should be told to not take the antibiotic with antacids or with milk or other dairy products. For patients receiving the IHS Diabetic Protocol, the dentist should warn the patient of these adverse properties, and the prescription should look as follows:
Rx: Doxycycline, 100 mg
Disp: 28 tabs
Sig: Take 1 tab every 12 hours for two weeks (while undergoing periodontal therapy)
Metronidazole (Flagyl) is a broad spectrum bacteriocidal antibiotic that also has several adverse effects possible. These include GI effects, oral effects (ulcerations, metallic taste), CNS effects, and renal toxicity. Most importantly, alcohol use (even swishing with an alcohol-based mouthwash) is contraindicated with metonidazole.
Quinolones and fluoroquinolones (Cipro, Floxin) are broad spectrum, bacteriocidal antibiotics that are not routinely used to treat dental infections, especially in light of the fact that due to the 9/11 aftermath, there has been a 40% increase in bacterial resistance to these drugs just within the last two years.
Fluconazole (Diflucan) is a systemic antifungal agent that is the drug of choice for oral candidiasis. It is important for the dental provider to also treat the denture of the edentulous patient when prescribing Diflucan, which may be prescribed as follows:
Rx: Diflucan, 100mg tablets
Disp: 15 tablets
Sig: Take 2 tablets the first day, then 1 tablet daily for 13 days
Acyclovir (Zovirax) is an antiviral drug that is the drug of choice for treating herpetic lesions, and can be prescribed as follows:
Rx: Zovirax Ointment, 5%
Disp: 15 g
Sig: Apply small amount to affected area every three hours six times a day for 7 days
At this time, there is inconclusive evidence of the efficacy of Acyclovir, and this drug is not on the service unit formulary.
An alternative, Abreva (10% cream), is available as an over-the-counter topical preparation, but is quite expensive to the patient (around $17 per tube).
Frequently asked questions (FAQ’s)
My patient is already taking antibiotics for an infection. How do I provide, or do I need to provide, SBE prophylaxis?
The dentist will need to provide SBE prophylaxis as recommended by the
AHA guidelines as if the patient weren’t taking other antibiotics, with one exception: if the patient has taken amoxicillin for seven days or more, then the dentist should prescribe an antibiotic other than amoxicillin for SBE prophylaxis.
If the patient’s physician dictates that a certain antibiotic be used for SBE prophylaxis, and this contradicts with current AHA guidelines, who do you follow?
The AHA guidelines should be followed.
What antibiotics should never be used for SBE prophylaxis?
Erythromycins and tetracyclines.
Should patients with total joint replacements, should SBE prophylaxis be provided?
Although there is no conclusive evidence that prophylactic antibiotics are necessary for patients with total joint replacements, many physicians and orthopedists request prophylactic coverage for high-risk dental procedures. AHA and CDC guidelines state that high-risk patients be covered with prophylactic antibiotics before high-risk dental procedures.
Who is considered to be a high-risk patient in regard to prophylaxis for joint replacements?
Patients that are otherwise immunocompromised – HIV, Type I diabetics, rheumatoid arthritis, joint replacement within the past two years.
What is considered to be a high-risk dental procedure in regard to prophylaxis for joint replacements?
Extractions or other oral surgery, scaling and root planing, endodontics. Periodontal probing may be considered a high-risk dental procedure.