Infective endocarditis (IE) is a microbial infection of the endothelial surface of the heart or heart valves that most often occurs in proximity to congenital or acquired cardiac defects.
IE is a disease of significant morbidity and mortality and is difficult to treat.
Historically, various dental procedures have been reported to be a significant cause of IE, because bacterial species found in the mouth frequently have been found to be the causative agent.
In addition, whenever a patient is given a diagnosis of IE caused by oral flora, dental procedures performed at any point within the previous severalmonths typically have been blamed for the infection.
As a result, antibiotics have been administered before certain invasive dental procedures in an attempt to prevent infection.
It is important to note, however, the effectiveness of such prophylaxis in humans has never been substantiated, and accumulating evidence more and more questions the validity of this practice.

Infective Endocarditis

Introduction

Risks to the dental patient

Treatment Planning for the At-Risk Patient

Complications of infective endocarditis:
- Severe valvular dysfunction leading to heart failure and death
- Myocardial infarction from emboli
- Stroke from emboli
Complications of antibiotic prophylaxis
- Anaphylaxis
- Increased antibiotic resistance

AHA 2007 Guidelines for Antibiotic Prophylaxis

High risk conditions and procedures for endocarditis

Antibiotic regimens recommended for prophylaxis

Other Methods to Decrease Bacteremia

Oral antimicrobial rinses (e.g., chlorhexidine, povidone-iodine) to reduce the frequency of bacteremia associated with dental procedures.
- Evidence shows that there is no clear benefit associated with its use.
The establishment and maintenance of optimal oral hygiene is the most effective way to decrease daily bacteremia

The antibiotic was inadvertantly not administered before the procedure
- The dosage may be administered up to 2 hours after the procedure is completed
The patient is already taking penicillin or amoxicillin for eradication of an infection. Resistance to these medications is likely.
- Clindamycin, azithromycin or clarithromycin should be used if prophylaxis is immediately necessary. Cephalosporins exhibit cross-resistance and so should be avoided.
- Or, wait at least 10 days after completion of antibiotic therapy. The usual regimen can then be used.
The duration of the dental appointment is longer than 6 hours.
- A second dose of the antibiotic should be administered.
How often can a patient requiring antibiotic prophylaxis be seen?
- Every 10 days if the same antibiotic is to be used.
What if a patient needs to be seen before this interval is up?
- Use an alternate antibiotic

Special Conditions

A more aggressive strategy (i.e., extractions) for highly questionable teeth to reduce the daily bacterial load
The establishment and maintainence of optimal oral health by prompt and complete treatment by the dental team the most effective way to decrease the risk of endocarditis in at risk patients.

References

Conditions for Which Antibiotic Prophylaxis is NOT Recommended

Antibiotic prophylaxis has been advocated for patients with the following conditions when they undergo dental treatment. However, no evidence of need or efficacy to prevent infections has been documented.

The following conditions/devices have NOT been found to be susceptible to distant site infection from bacteremia secondary to invasive dental treatment. Antibiotic prophylaxis is NOT recommended

Chronic indwelling catheters of any kind
Renal dialysis arteriovenous shunt
Cerebrospinal fluid shunts
Vascular grafts
Orthopedic screws, plates or pins
Prosthetic joints
Implanted pacemaker or defibrillator
Coronary artery stents
Breast implants
Penile implants
Valvular dysfunction due to:
- Previous use of fenfluramine and/or dexfenfluramine
- IV drug use
- Kawasaki disease
- Hypertrophic cardiomyopathy
- Systemic lupus erythematosus

The following conditions have NOT been found to cause increased susceptibility to dental/orofacial infection. Antibiotic prophylaxis is NOT recommended. Antibiotics should be prescribed when required for CURRENT infections

Immunosuppressive drugs (e.g., steroid therapy, chemotherapy, DMARDs)
Autoimmune disease (e.g., systemic lupus erythematosus, rheumatoid arthritis)
Insulin-dependent diabetes
HIV infection/AIDS
Splenectomy
Severe neutropenia
Sickle cell anemia
Head and neck radiotherapy
Solid organ transplants
Stem cell and bone marrow transplants

Assumptions behind the practice of antibiotic prophylaxis

Dental manipulation of oral tissues causes an abrupt increase of oral bacteria in the blood, lasting minutes to hours.
- Dental procedures CAN cause bacteremias. However, so can normal daily activities such as eating and oral hygiene procedures which could cause multiple bacteremias each day.
This increase in bacterial loading can cause devastating infections systemically or to specific structures or devices.
- No studies prove that the magnitude of bacteremia caused by dental procedures is higher than for daily activities.
A large dose of antibiotics shortly before the dental procedure will counter the effects of this increase, and decrease the numbers of infections cause by this "transient bacteremia".
- While studies have shown that amoxicillin reduces the bacteremia associated with dental procedures, there have been no studies that show the efficacy of antibiotic prophylaxis to prevent infective endocarditis in dental patients.

Dental Management of the Medically Compromised Patient. Little, Falace, Miller and Rhodus. 8th Edition

J Andrade, E. Stadnick, A Mohamed. Infective endocarditis practice: An update for clinical practice. BCMJ 2008 50:8, 451-455.