Infective Endocarditis: Etiology and Pathophysiology

• Infective Endocarditis involves infection of the endocardial surface of the heart
• Infective Endocarditis may affect one or more heart valves
• Prior to penicillin, infective endocarditis was a fatal condition
• There are 15,000 new cases of infective endocarditis diagnosed in the United States each year

Etiology and Pathophysiology

• Cardiac valves and other adjacent structures in the heart become infected after exposure to microemboli from bacteria or fungi circulating in the blood stream
• Endocardial surfaces previously damaged from valvular heart disease, endocarditis, surgery, or pacemaker wires provide a favorable environment for thrombus formation as of 2013
• Vegetation lesions on valves include fibrin, leukocytes, platelets, and microbes
• Fibrin, leukocytes, platelets, and microbes must adhere to the valve or endocardium
• Embolization can occur by portions of vegetation that break off and enter into circulation
• This can result in embolus formation elsewhere in body or within heart, depending on location of vegetation

Causative Organisms

• Bacterial organisms like Streptococcus viridans, Staphylococcus aureus, and Enterococcus can cause infective endocarditis
• Other pathogens that lead to this condition inclue viruses and fungi

Risk Factors

• Risk factors include include age, intravenous drug abuse, and prosthetic valves/valve replacements
• Other risk factors include use of intravascular devices, hemodialysis and pacemaker endocarditis

Clinical Manifestations

• Nonspecific clinical manifestations include a fever, which occurs in patients along with heart murmurs
• Other clinical manifestations include chills, weakness, malaise, fatigue, and anorexia
• Arthralgias, myalgias, back pain, abdominal discomfort, weight loss, headache, and clubbing of fingers are also clinical manifestations
• Vascular manifestations include subungual splinter hemorrhages in nail beds and black longitudinal streaks on nails, also dark red linear lesions
• Petechiae are also clinical manifestations, with a red spot indicating loss of blood in tissue
• You may also see Roth's spots with hemorrhagic lesions in the retina as well as Osler nodes with tender subcutaneous nodules found on the distal pads of the digits
• A patient may also develop Janeway lesions with Nontender maculae on the palms and soles
• Heart failure is observed in up to 80% with aortic valve endocarditis
• There are manifestations secondary to embolism, therefore diagnosis is established by Dukes Criteria

Antibiotic Therapy

• Streptococcal endocarditis can be treated with IV antibiotic therapy
• Antibiotic therapy may include Penicillin G, a natural Penicillin or Ceftriaxone (Rocephin), a 3rd generation Cephalosporin when is most potent form
• Gentamycin (Garamycin), an aminoglycoside, is used and is nephrotoxic, so one must check peak and trough levels to monitor therapy
• Vancomycin (Vancocin) is also used, a natural bactericidal that is nephrotoxic; check peak and trough levels to monitor therapy

Antibiotic Therapy for Staphylococcal endocarditis

• Staphylococcal endocarditis is treated with IV antibiotic therapy like Nafcillin (Nafcil) or Penicillinase Resistant Penicillin (anti-Staphyloccal Penicillin)
• Like with Streptococcal endocarditis, Gentamycin (Garamycin) – Aminoglycoside or Vancomycin (Vancocin) – Natural bactericidal antibiotics are prescribed
• These prescriptions are nephrotoxic, so check peak and trough levels to monitor therapy

Antibiotic Therapy for Fungal endocarditis

• Fungal endocarditis is treated with IV anti-fungal therapy, namely Amphotericin B (Fungizone)
• This antibiotic has many adverse effects: cardiac dysrhythmias, Neurotoxicity, Tinnitus, Visual disturbances, Convulsions, Renal toxicity, Hepatotoxicity, Fevers and Anemia

Collaborative Care

• Monitor antibiotic serum levels (e.g., peak and trough) during Antibiotic administration
• Subsequent blood cultures are used to check if therapy is adequate, and renal function is monitored
• Fungal and prosthetic valve endocarditis responds poorly to antibiotics
• Valve replacement is often required to properly treat these diseases

Collaborative Care: Prophylactic antibiotic treatment is used for patients with history of endocarditis having:

• Certain dental procedures
• Respiratory tract incisions
• GI wound infection
• Urinary tract infection

SDOH

• Social determinants of health associated with this illness are crowding, dwelling characteristics, low education level and employment status, poor nutrition, and low social class.
• Vancomycin IV per unit costs $ 26-$30 and one Bottle of Vancomycin costs $358
• Amphotericin B (Fungizone) costs $50 per injection