Infective Endocarditis: Etiology, Pathophysiology

• Infective endocarditis involves an infection of the heart's endocardial surface.
• It can affect one or more of the heart valves.
• Before penicillin, it was often fatal.
• About 15,000 new cases are diagnosed annually in the United States.

Etiology and Pathophysiology

• Cardiac valves become infected following exposure to microemboli from circulating bacteria or fungi.
• Endocardial surfaces damaged by valvular heart disease, endocarditis, surgery, or pacemaker wires encourage thrombus formation.
• Vegetation refers to lesions on valves and includes fibrin, leukocytes, platelets, and microbes.
• Vegetation adheres to the valve or endocardium.
• Embolization can occur when vegetation breaks off.
• Vegetation fragments can enter circulation and cause embolus formation elsewhere in the body or within the heart.

Causative Organisms

• Bacterial causes include Streptococcus viridans, Staphylococcus aureus, and Enterococcus.
• Other pathogens include viruses and fungi.

Risk Factors

• Risk factors include age, IV drug abuse (IVDA), prosthetic valves (valve replacements), use of intravascular devices, hemodialysis, and pacemaker endocarditis.

Clinical Manifestations

• Clinical manifestations are nonspecific.
• Fever occurs in patients.
• Heart murmurs, chills, weakness, malaise, fatigue, and anorexia can occur.
• Other symptoms include arthralgias, myalgias, back pain, abdominal discomfort, weight loss, headache, and clubbing of fingers.

Clinical Manifestations: Vascular

• Vascular manifestations include subungual splinter hemorrhages in nail beds, black longitudinal streaks on nails, and dark red linear lesions.
• Petechiae presents as red spots, indicating blood loss in tissue.
• Roth's spots appear as hemorrhagic lesions in the retina.
• Osler nodes are tender subcutaneous nodules on the distal pads of the digits.
• Janeway lesions are nontender maculae on the palms and soles.

Additional Manifestations

• Heart failure can occur in up to 80% of aortic valve endocarditis cases.
• Manifestations are often secondary to embolism.
• Diagnosis is established by Dukes Criteria.

Antibiotic Therapy: Streptococcal Endocarditis

• IV antibiotic therapy is used.
• Options include Penicillin G (natural Penicillin), Ceftriaxone (Rocephin) which is a 3rd generation Cephalosporin, and Gentamycin (Garamycin) which is an Aminoglycoside.
• Gentamycin can be nephrotoxic, requiring monitoring of peak and trough levels.
• Another option is Vancomycin (Vancocin), which a natural bactericidal.
• Vancomycin can be nephrotoxic, also requiring monitoring of peak and trough levels.

Antibiotic Therapy: Staphylococcal Endocarditis

• IV antibiotic therapy is used.
• The therapy consists of Nafcillin, which a Penicillinase Resistant Penicillin (anti-Staphyloccal Penicillin).
• Another option is Gentamycin (Garamycin), which an Aminoglycoside, could be used
• Gentamycin can be nephrotoxic, requiring monitoring of peak and trough levels.
• Another option is Vancomycin (Vancocin), which a natural bactericidal.
• Vancomycin can be nephrotoxic, also requiring monitoring of peak and trough levels.

Antibiotic Therapy: Fungal Endocarditis

• IV anti-fungal therapy is used.
• Amphotericin B (Fungizone) is an option but has many adverse effects.
• These adverse effects include cardiac dysrhythmias, neurotoxicity, tinnitus, visual disturbances, convulsions, renal toxicity, hepatotoxicity, fevers, and anemia.

Collaborative Care

• Antibiotic administration should include monitoring antibiotic serum levels (e.g., peak and trough).
• Subsequent blood cultures are needed to check if therapy is adequate.
• It's important to monitor renal function.
• Fungal and prosthetic valve endocarditis responds poorly to antibiotics.
• Valve replacement is often required.
• Prophylactic antibiotic treatment is recommended for patients with a history of endocarditis before certain dental procedures, respiratory tract incisions, GI wound infection, and urinary tract infection.

SDOH Factors

• SDOH factors that impact rates of infective endocarditis include crowding, dwelling characteristics, low education level and employment status, poor nutrition, and low social class.

Costs

• The cost of Vancomycin IV per unit $26-$30.
• The cost of Vancomycin po 1 Bottle, generic $358.
• The cost of Amphotericin B (Fungizone) is $50 per injection.