Description
Infective endocarditis (IE) is defined as an infection of the endocardial surface of the heart (heart valves and
mural endocardium) by microorganisms (mainly bacteria) hence also called bacterial endocarditis.
Risk factors
• Congenital heart disease especially Cyanotic CHD
• Rheumatic heart disease
• Prosthetic heart valve
• History of endocarditis
• IV drug use or chronic IV access
• Immunocompromised (HIV, diabetes)
Classification
Acute infective endocarditis
Caused by virulent organisms, like S. aureus, enterococci and streptococcus, which are harmful even on healthy endocardium. Onset of disease is stormy with high grade fever and causes destructive lesions on the endocardium like ulcerations, perforation, regurgitation and ring abscesses especially around prosthetic valves.
Subacute infective endocarditis
Caused by relatively low virulent organisms e.g. S.viridans and HACEK group (Haemophilus, Aggregatibacter, Corynebacterium, Eikanella, Kingelle). It runs a more insidious course:
• low grade fever, anorexia, weight loss, influenza like syndromes, myalgia, pleuritic pain
• No specific heart pathological features. Characterised by slowly growing chronic inflammation, fibrosis and with tightly held endocardial vegetations. Chronicity of this type of IE causes
• chronic antigenemia which in turn is prone to immune complex formation.
Investigations
• FBC/DC
• ESR
• ECG/ECHO
• CXR
• Blood culture 3 cultures within 24 hours
A fever with new/or changing murmur is IE until proven otherwise.
Duke’s criteria for the diagnosis of IE
Table 48: Duke’s criteria for the diagnosis of IE
|
Major criteria |
Minor criteria |
|
Positive blood culture Typical microorganism consistent with IE from ≥2 blood cultures, Microorganisms consistent with IE from persistently positive blood cultures, defined as: • ≥2 Positive cultures of blood samples drawn >12 h apart or • All of 3 or a majority of ≥4 blood cultures, irrespective of the timing • Positive blood culture for Coxiella burnetii or antiphase-I immunoglobulin G antibody titre >1:800 Evidence of endocardial involvement Positive echocardiogram, defined as: Oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation or Abscess OR New partial dehiscence of prosthetic valve OR New valvular regurgitation (worsening or changing of pre- existing murmur not enough) |
• Predisposition: predisposing heart condition or IV drug use • Fever: temperature ≥38.0°C • Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, conjunctival haemorrhages, and Janeway lesions • Immunologic phenomena: glomerulonephritis, Osler nodes, Roth’s spots, and rheumatoid factor • Microbiological evidence: positive blood culture but does not meet a major criterion as noted above or serological evidence of active infection with organism consistent with IE |
Diagnosis is made when there are 2 major criteria or 1 major plus 3 minor or 5 minor criteria
Treatment
Table 49 Management of Infective endocarditis
|
|
Drugs |
Dosage |
Duration |
Remarks |
|
1st Line |
Crystalline Penicillin (X Pen) 50-100,000 IU/kg in 4 divided doses/day And, Gentamicin 3-5mg/kg/day in 2-3 divided doses/day |
4 weeks |
Then, Ciprofloxacin 15mg/ kg/day in 2 divided doses for 2 weeks |
|
|
|
Ceftriaxone 80-100mg/kg/day 1-2 times daily/day And, Gentamicin 3-5mg/kg/day 2-3 divided doses/day |
4 weeks |
Then, Ciprofloxacin 15mg/ kg/day in 2 divided doses for 2 weeks |
|
|
2nd Line |
Vancomycin 30-40mg/kg/day in 4 divided doses And, Gentamicin 3-5mg/kg/day in 2-3 divided doses |
4 weeks |
Then, Ciprofloxacin 15mg/ kg/day in 2 divided doses for 2 weeks |
|