Infective Endocarditis (IE) – is an infection of the endocardial surface of heart, including valves or a septal defect. The infection is bacterial in origin but other organisms may also be a cause, which travel through blood stream to attach themselves to the damaged heart areas. These agents include:

  • Streptococcal species (50-80% of cases)
  • Staphylococcal species
  • Enterococcal species
  • HACEK organisms (Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens and Kingella kingae)
  • Candida spp.

The bacteria gain access to bloodstream through an infection, catheters or needles and dental procedures, which along with fibrin, platelets and antibodies form masses called vegetations (lesions). While these lesions can form on normal heart valves, 60% of IE cases have a pre-disposing cardiac condition. Pre-disposing factors include:

  • Artificial heart valves (10-15% of cases)
  • Congenital heart defects
  • History of endocarditis
  • Damaged heart valves
  • History intravenous drug abuse

IE poses a great challenge to generalist and is rarely an obvious diagnosis, and the primary guide is the modified Duke criteria.

Major criteria:

  • Typical micro-organisms from 2 sets of blood cultures, taken separately from different sites
  • Typical micro-organisms from serial blood cultures
  • One positive blood culture for Coxiella burnetti or positive serology for C. burnetti, Bartonella species or Chlamydia psittaci.
  • Positive PCR (polymerase chain reaction) for certain genetic targets

Minor Criteria:

  • Positive echocardiogram for vegetations, abcesses or prosthetic valve dehiscence

Presence of any of these signs along with constitutional symptoms requires immediate medical attention. IE is characterized by the following clinical features:

  • Constitutional symptoms (fever, night sweats, anorexia, rigors and weight loss)
  • A new murmur or a change in an existing one
  • A variety of skin lesions are found in IE:
    • Osler’s nodes (tender lesions on finger pulp, thenar/hypothenar eminences)
    • Janeway lesions (non-tender lesions on palm and sole)
    • Splinter hemorrhages
    • Petechiae
    • Clubbing
  • Roth spots (hemorrhages in retina)
  • Splenomegaly (tender, painful spleen with a rub)
  • Neurological features:
    • State of confusion
    • Hemiplegia
    • Sensory dysfunction
    • Subarachnoid hematoma
  • Renal features (loin pain, haematuria and glomerulonephritis)

Investigations carried out to rule out other causes and diagnose the infection include

  • Baseline blood tests and blood cultures
  • 12-lead ECG
  • Transoesophageal echocardiogram
  • Chest X-ray
  • CT scan
  • MRI

If IE is managed with effective treatment there’s a 70% survival rate. High dose IV antibiotics are given as soon as the diagnosis is confirmed. In case of persistence of fever and failed conservative therapy, heart failure or embolic phenonema, surgical intervention may be required involving valve replacement and at times aortic root replacement for abscesses followed by an antibiotic course.