OralMedCh2

Chapter Overview

• Title: Infective Endocarditis Prophylaxis

• Author: Donal Scheidel, DDS, Associate Professor, Creighton School of Dentistry

Objectives

• Understand reasoning behind antibiotic prophylaxis for infective endocarditis prevention.

• List the guidelines for premedication.

• Determine the appropriate antibiotic for premedication.

Overview

• Classification changes: acute/subacute vs. causative organism/valve type/location of acquisition.

• Significant morbidity/mortality associated with infective endocarditis (IE).

• Dental procedures related to the occurrence of IE.

• Antibiotics should be administered before dental appointments in high-risk populations.

• Literature lacks substantiation for effectiveness except in specific medical conditions.

Epidemiology

• More common in men and among middle-aged and elderly individuals.

• Rates of IE are higher in specific populations, notably intravenous drug users (IVDUs).

• Lifetime risk calculations displayed in Table 2-1.

• Mitral valve prolapse (MVP), with or without regurgitation, is a common cause of non-vegetative endocarditis (NVE).

• Patients with a history of cardiac valve replacement or previous IE incidents are at greater risk.

Etiology

• 80-90% of community-acquired cases are caused by staphylococci, enterococci, or streptococci.

• Variability in causative agents based on acquisition location, valve type (native/prosthetic), and IVDU incidence.

• Viridans streptococci are the most common causative agent.

• Increasing incidence of staphylococci-induced IE, accounting for 30-40% of cases (commonly Staphylococcus aureus).

• Staphylococcus aureus is prevalent in infective endocarditis among IV drug users.

Pathophysiology

• Infection begins with damage to the endothelial surface of cardiac valves due to:

  • High-velocity blood flow

  • Flow dynamics from high to low-pressure chambers

  • Flow over narrowed orifices at high velocity.

• Formation of fibrin/platelet mass over damaged endothelium.

• Bacterial colonization occurs with protective fibrin/platelet coatings.

• Continuous bacteremia results as bacteria enter the bloodstream from vegetative lesions.

Complications

• Major complications of infective endocarditis include:

  • Heart failure

  • Stroke

  • Myocardial infarction (MI)

  • Pulmonary emboli

  • Renal dysfunction

Signs and Symptoms of IE

• Common clinical signs include:

  • Fever

  • New heart murmur

  • Positive blood culture

• 80% of patients exhibit symptoms within two weeks or less.

• Symptoms include petechiae of palpebral conjunctiva, buccal/palatal mucosa, extremities, and splinter hemorrhages of nail beds.

• Diagnosis requires:

  • Two major criteria, or

  • One major plus three minor criteria, or

  • Five minor criteria.

• Major criterion involves positive blood cultures or evidence of endocardial involvement.

• Minor criteria include predisposing heart conditions/IVDU, fever, vascular, and immunologic phenomena.

Laboratory Findings

• Common findings:

  • Positive bacterial blood cultures

  • Elevated white blood cell (WBC) count, normocytic anemia

  • Possible hematuria and proteinuria

Medical Management

• Mortality rates can vary significantly:

  • 5% for patients with NVE caused by Strep viridans.

  • 80% mortality for fungal endocarditis.

• Standard treatment includes:

  • Parenteral penicillin and gentamicin for 4-6 weeks.

  • Addition of vancomycin for methicillin-resistant Staphylococcus infections.

  • Surgical interventions to repair any damage.

Dental Management

• AHA guidelines are aimed at prevention.

• Patients are subject to daily bacteremia.

• Dental procedures typically induce less bacteremia than the infection threshold observed in animals.

• Most patients with IE had no dental procedure in the two weeks prior to diagnosis.

• Improving oral hygiene and eliminating oral disease can aid in prevention.

Management Factors

• Dental procedures leading to bleeding are factors to consider.

• Effectiveness of antibiotics in reducing bacterial load is debated.

• Documented incidences of patients developing IE post-antibiotic premedication.

• Statistically, there's a 1/14 million chance of developing IE from dental procedures in the general population, increasing to 1/95,000 in patients with previous IE.

• AHA cites an exceedingly small number of IE cases directly caused by dental-related bacteremia.

Current AHA Recommendations

• Prophylaxis is advised for patients with:

  • Prosthetic heart valves

  • A history of previous infective endocarditis

  • Cardiac transplant recipients with valve disorders

  • Congenital heart disease (CHD), especially unrepaired cases or repaired cases with prosthetic material within the last 6 months.

Dental Procedures With Minimal Risk

• Procedures that do not typically require antibiotic prophylaxis include:

  • Taking x-rays

  • Injections through non-infected tissue

  • Placement or adjustment of removable orthodontic/prosthetic appliances

  • Shedding of primary teeth

  • Minor oral trauma

Antibiotic Regimen

• Amoxicillin 2g administered 30-60 minutes prior to appointment (50mg/kg for children).

• For penicillin-allergic patients:

  • Azithromycin/clarithromycin 500mg, or doxycycline 100mg, 30-60 minutes prior.

• If the patient is already on an antibiotic, a different class should be used (e.g., penicillin to azithromycin).

• Extended appointments may require re-dosing amoxicillin after 6 hours of initial dosing.

• If a dental procedure begins without premedication, antibiotics can still be administered up to 2 hours later.

Other Considerations

• Patients on warfarin or those with prosthetic valves have specific risk factors.

• Heart transplant recipients show increased incidence of valvular dysfunction.

• Nonvalvular cardiovascular devices pose risks as well.

• Patients with intravascular devices should be managed with care.

• Sequential dental appointments should be spaced 10 days apart for patients needing prophylaxis.

Current AAOS Recommendations

• Current advisories regarding prophylactic antibiotics for patients with hip and knee prosthetic joint replacements.

• Decision-making for these situations is at the discretion of the patient and orthopedic surgeon.

AAOA Recommendations

• Higher risk patients include those who are:

  • Immunocompromised

  • Have a history of prosthetic joint infections

  • Suffer from comorbidities such as diabetes, obesity, smoking, or autoimmune diseases.

One Final Note

• References the March 2015 guideline by the National Institute for Health and Clinical Excellence (NICE), which assesses antibiotics' benefits against adverse effects and antibiotic resistance. It highlights the recommendation against routine prophylaxis for defined interventional procedures.