INFECTIVE ENDOCARDITIS

Question 1

Definition

Answer 1

Infection of the endocardium or vascular endothelium of the heart

Question 2

Types (2)

Answer 2

1- Acute: mostly by S.aureus, normal valve, fatal in <6 weeks if untreated
2- Subacute: More common, Streptococcus viridans or Enterococcus, damaged valve, takes >6 weeks to cause death

Question 3

Etiology (6)

Answer 3

1- Native healthy valve: Staph. aureus
2- Native diseased valve: Stept. viridans
3- Prosthetic valve; early onset (<60 days of surgery): Staph. epidermidis (acquired in perioperative period)
4- Prosthetic valve; late onset (>60 days of surgery): Streptococci (follows bacteremia)
5- IV drug users: S.aureus mostly, others are Enterococci/Streptococci/Fungi (candida)/Gram -ve rods (Pseudomonas), usually right-sided valves
6- Culture negative: Coxiella burnetti, Bartonella, Chlamaydia, and Legionella

Question 4

Signs and Symptoms (5)

Answer 4

1- Constitutional symptoms: fever, weight loss, anemia and slight splenomegaly (IMP)
2- RULE: new heart murmur + fever —> must rule out infective endocarditis
3- Heart failure and murmurs due to valve destruction (vegetations made up of fibrin, platelets, and infectious organisms destroying the valves)
4- Embolization of vegetations:
- Vascular phenomena: Janeway lesions (painless)
- Metastaic abscesses: brain, kidneys, spleen, and if right-sided, lungs
5- Immune complex deposition:
- Splinter (nail bed) hemorrhages
- Roth’s spots in retina
- Osler’s nodes (painful)
- Arthalgia
- Glomerulonephritis with microscopic hematuria

Question 5

Investigations (8)

Answer 5

1- Blood cultures (taken before antibiotics are started; 3 sets taken over 24 hours)
2- Serological tests if unusual organisms (culture -ve; ex: Q fever, chlamaydia)
3- CBC: normocytic normochromic anemia, leukocytosis, raised ESR
4- Echo: Transthoracic. Transesophageal is more sensitive than transthoracic incase of prosthetic valve
5- CXR: Heart failure or evidence of embolization to lung if right-sided (pulmonary infarction or pneumonia)
6- ECG: MI if embolization to coronary arteries, or conduction defects
7- Urinalysis: Hematuria
8- Raised serum Ig and low complement due to immune complex deposition

Question 6

Diagnosis: Modified Duke Criteria (2)

Answer 6

• Definite diagnosis requires:
  
  • 2 Major criteria OR
  • 1 Major and 3 Minor OR
  • 5 Minor OR
  • only direct evidence of infective endocarditis e.g. vegetation histology or culture
• Possible endocarditis diagnosis requires: 1 Major and 1 Minor or 3 Minor

Question 7

Major criteria (2)

Answer 7

1- 2 positive blood cultures for an organism known to cause IE OR persistent bacteremia two +ve 12 hours apart or 3 of 4 +ve drawn over one hour
2- Echo evidence: oscillating mass on valve or supporting structures or abscess or new valvular regurgitation or partial dehiscence of prosthetic valve

Question 8

Minor criteria (7)

Answer 8

1- Predisposing factor- cardiac lesion, IV drug use
2- Fever > 38C
3- Evidence of emboli or vasculitis
4- Immunological features (osler nodes, nephritis)
5- Echo of uncertain significance (consistent with IE but not meeting major criteria)
6- Serology for Q fever or chlamaydial infection
7- Single +ve blood culture of uncertain etiology

Question 9

Treatment

Answer 9

IV Bactericidal antibiotics for 2 weeks, then oral for 2-4 weeks
- Empirical antibiotics: benzylpenicillin + gentamicin generally, unless staphylococci are suspected then vancomycin + gentamicin
- Definitive therapy depends on culture and sensitivity results

Question 10

Cases requiring acute valve replacement (4)

Answer 10

• Severe heart failure
• Worsening renal failure
• Extensive damage to the valve
• Prosthetic valve

Question 11

Prophylaxis

Answer 11

• NOT INDICATED for patients when they are diagnosed
• Taken if patient has BOTH a qualifying cardiac indication AND a qualifying procedure
• Use amoxicillin. If allergic to penicillin, use clindamycin or azithromycin

Question 12

Prophylaxis- Cardiac indications (6)

Answer 12

• Prosthetic heart valve
• Hx of IE
• Transplanted heart with valvular disease
• Unrepaired cyanotic congenital heart disease
• Repaired congenital heart disease (CHD) with prosthetic material, during the first 6 months after procedure
• Repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device

Question 13

Prophylaxis- Procedures (4)

Answer 13

• Dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa
• Invasive respiratory tract procedures that involve incision or biopsy of the respiratory mucosa
• Surgical procedure that involves infected skin, skin structure, or musculoskeletal tissue
• No prophylaxis for genitourinary or gastrointestinal tract procedures