Prophylaxis for Bacterial Endocarditis Prior to Dental Procedures in Children

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Providing prophylaxis for bacterial endocarditis (BE) prior to dental procedures has long been a topic of controversy because the disease has a low incidence but a relatively high mortality rate. Understanding which patients need prophylaxis and which antibiotics are appropriate is important for health care providers so that high-risk patients are treated appropriately. The incidence of BE in children is quite low, with a broad range of estimates being reported in the literature, all below 0.1%.

In the pediatric population, risks for BE are slightly different than those for adults, with congenital heart disease (CHD) and postsurgical cases being leading risk factors in children. The causes of endocarditis also are changing as the incidence of rheumatic fever declines, the number of immunocompromised patients with long-term central catheters increases, and surgical procedures continue to advance, allowing for more complex and invasive procedures.

Bacterial endocarditis is believed to be due to transient bacteremia, although a direct association has never been proved. In particular, patients with certain types of CHD are at risk for bacterial endocarditis because of the abnormal blood flow through their hearts. Introduction of bacteria into the bloodstream generally causes only a transient bacteremia in patients with normal cardiac flow. Blood flow in patients who have congenital heart disease often can consist of pooling of blood in the ventricles; this pooling allows bacteria time to dwell and the opportunity to colonize the myocardium. Any procedures that can cause a transient bacteremia can be problematic for patients with CHD. In particular, dental procedures can create a temporary bacteremia as small lacerations along the gum line allow oral flora to enter the bloodstream. It also has been shown that relatively routine activities such as brushing teeth or chewing gum can create a portal of entry for bacteria. Once vegetation begins to form, the risk for the patient escalates beyond the damage done to the myocardium, as high blood flow against the vegetation can cause an embolism to break off and travel to other parts of the body.

The offending pathogen in culture-positive cases is most frequently Streptococcus viridians, although the incidence of Staphylococcus aureus infections is becoming more frequent. Staphylococcal infections are particularly worrisome because they have been shown to have an affinity for certain receptors on the endothelium of cardiac valves. However, the relative infrequency of positive cultures in patients with endocarditis makes treatment difficult and often necessitates the use of broad-spectrum antibiotics.

While some evidence exists that the bacteremia induced by dental, surgical, or other procedures can cause endocarditis, there is a consistent lack of data supporting the efficacy of antibiotic prophylaxis for BE. Whether to treat patients at risk is the topic of much controversy, although the popular opinion tends to lie on the side of prophylaxis because the treatment is so benign and the mortality rate from endocarditis is so great.

The most recent recommendations from the American Heart Association suggest treating patients with prophylactic antibiotics for BE only if they fall in the high-risk or moderate-risk categories (Box 1). Patients who fall in the negligible risk categories have no greater risk than the general population for developing BE, and therefore antibiotic prophylaxis is not recommended (Box 2). Dental practitioners and other health care professionals working with patients in the high- or moderate-risk categories should ensure that prophylaxis is given if any type of procedure that might introduce bacteria is undertaken.

While the main focus of this discussion is on antibiotic prophylaxis against bacteremia, the first step in prevention of bacteremia is the consistent practice of antiseptic measures prior to dental procedures. Antibiotic therapy generally is focused on the likely pathogen, S. viridians. Current guidelines recommend giving oral prophylactic doses an hour before the procedure to allow time for the antibiotic to be absorbed and reach a peak level in the blood (Table 1). The most commonly used prophylactic agent is amoxicillin, which is a β-lactam antibiotic whose spectrum is broader than that of penicillin and which is readily available in many dosage forms, many of which are flavored, making the administration of this drug to children easier. Amoxicillin also is available in a generic form, making antibiotic prophylaxis a very affordable measure. The main disadvantage to amoxicillin, to its intravenous equivalent ampicillin, and to the cephalosporins cephalexin, cefadroxil, and cefazolin, is that these drugs are very susceptible to β-lactamase enzymes, which commonly are secreted by gram-negative bacteria. However, the incidence of gram-negative BE is very low, so this should be a negligible concern. As with any antibiotic in the penicillin family, health care professionals should first screen patients for a penicillin allergy and have epinephrine doses available in the event that an anaphylactic reaction were to occur.

TABLE 1. Recommended antibiotic prophylactic regimens for children.

IM, Intramuscularly; IV, intravenously.

Data from Dajani, Taubert, Wilson, Bolger, Bayer, Ferrier, et al., 1997.

The macrolide antibiotics, which may be used for patients who are allergic to penicillin, are clarithromycin and azithromycin. Macrolides work by binding to the 50 S ribosomal subunit of bacteria, inhibiting protein synthesis. Both of these drugs also are available in both tablet and suspension form, allowing for ease of administration to children. Clindamycin also acts by binding to the 50 S ribosomal subunit, inhibiting bacterial protein synthesis. It too is available in capsule, suspension, and intravenous formulations.

While the controversy over prophylaxis for bacterial endocarditis remains, the completion of a randomized prospective study to analyze the efficacy of prophylaxis cannot be expected, because prophylaxis exists as a guideline for care in most countries. Health care practitioners must make an educated decision regarding whether to provide prophylaxis, taking into account current guidelines and patient-specific factors.

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Reference 

1. Dajani AS, Taubert KA, Wilson W, Bolger AF, Bayer A, Ferrier P, et al. Prevention of bacterial endocarditis: Recommendations by the American Heart Association. Circulation. 1997;96:358–366
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