2. DEFINITION
Infective Endocarditis (IE) is a microbial infection of
the endocardial (endothelial) surface of the heart.
The vegetation is a variably sized amorphous mass of
platelets and fibrin in which abundant micro-
organisms and scant inflammatory cells are enmeshed.
Braunwald – Heart Disease
5. RISK FACTORS FOR SPECIFIC
PATHOGENS THAT CAUSE IE
Dental procedures, poor dental hygiene - viridans streptococci,
nutritionally variant streptococci, HACEK
• Prosthetic valves
– Early: coagulase negative staphylococci, S. aureus
– Late: coagulase negative staphylococci, viridans streptococci
• Gastrointestinal or genitourinary procedures - enterococci or S.
bovis (colon carcinoma)
• Nosocomial - S. aureus (including MRSA), Gram negatives,
Candida species
Brouqui and Raoult, Clin Microbiol Rev, 2001
6. PATHOGENESIS
Endothelium resistant to bacteria and thrombus formation
Endothelial injury and hypercoagulable state- high velocity jets, obstructive
lesions, aberrant flows, direct invasion by virulent pathogens can lead to non-
bacterial thrombotic embolism(NBTE)
Mitral regurgitation, Aortic stenosis, Aortic regurgitation, Ventricular Septal
Defect, complex congenital heart disease can create
NBTE
Most bacteria find NBTE a convenient site or nidus for
adherence
Virulent organisms- Staph. aureus, Strep. pyogenes, Strep. pneumoniae have
surface molecules which allow them to adhere to intact endothelium and to
exposed sub-endothelial tissues
If the adhering bacteria are able to survive serum cidal activity, peptides,
complement , antibody etc., they multiply – infective vegetation.
7. PATHOPHYSIOLOGY
The clinical manifestation IE result from:
1. The local destructive effects of intracardial infection;
2. The embolization of septic fragments of vegetations to
distant sites, resulting in infarction or infection;
3. The hematogenous seeding of remote sites during
continuous bacteremia and
4. An antibody response to the infecting organism with
subsequent tissue injury due to deposition of preformed
immune complexes.
11. DIAGNOSIS OF IE
Pathological criteria:
Microorganisms: demonstrated by culture or histology in a
vegetation, or in a vegetation that has embolized, or in an
intracardiac abscess, or
Pathological lesions: vegetation or intracardiac abscess
present, confirmed by histology showing active
endocarditis
Clinical criteria:
Two major criteria, or One major and three minor criteria, or
Five minor criteria.
12. DIAGNOSIS OF IE
MAJOR CRITERIA
Positive blood culture
Typical microorganism for infective endocarditis from two separate blood cultures
Viridans streptococci, Streptococcus bovis, HACEK group or
Community-acquired Staphylococcus aureus or enterococci in the absence of a primary
focus, or
Persistently positive blood culture, defined as recovery of a microorganism consistent with
infective endocarditis from:
Blood cultures drawn more than 12 hr apart, or
All of three or a majority of four or more separate blood cultures, with first and last drawn at
least 1 hr apart
Evidence of endocardial involvement
Positive echocardiogram
Oscillating intracardiac mass, on valve or supporting structures, or in the path of regurgitant
jets, or on implanted material, in the absence of an alternative anatomical explanation, or
Abscess, or New partial dehiscence of prosthetic valve, or New valvular regurgitation
(increase or change in preexisting murmur not sufficient)
13. DIAGNOSIS OF IE
MINOR CRITERIA
Predisposition: predisposing heart condition or intravenous drug use
Fever ,38.0°C (100.4°F)
Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic
aneurysm, intracranial hemorrhage, conjunctival hemorrhages, Janeway's lesions
Immunological phenomena: glomerulonephritis, Osler's nodes, Roth's spots,
rheumatoid factor
Microbiological evidence: positive blood culture but not meeting major criterion as
noted previously or serologic evidence of active infection with organism consistent with
infective endocarditis
Echocardiogram: consistent with infective endocarditis but not meeting major criterion
Adapted from Durack DT, Lukes AS, Bright DK: New criteria for diagnosis of infective
endocarditis: Utilization of specific echocardiographic findings. Am J Med
96:200, 1994.
14. DIAGNOSIS OF IE
OTHER TESTS
ECHOCARDIOLOGY
Transthoracic Echocardiology(TTE) 65% sensitive
Transoesaphageal Echocardiology(TEE) >90% sensitive, 6 – 18% false
negatives
Repeat in 7 – 10 days
CBC
Sed. Rate
C Reactive Protein
Immune Complexes
15. TREATMENT
ANTIBIOTICS
Ideal therapy includes a cell wall-active agent plus an effective
aminoglycoside to achieve bactericidal synergy.
Bactericidal, prolonged administration 4 – 8 weeks
Given IV
Knowledge of MIC of the pathogen is important.
Strep.viridans (pen.sensitive):
PenG 2-3 mU q 4hrly - 4weeks or
Ceftriaxone 2 g/d - 4weeks or
Vancomycin 15mg/kg q 12 hrly - 4weeks
Pen G 2-3 Mu q 4 hrly - 2weeks plus
Gentamicin 1mg/kg q 8hrly – 2weeks.
16. TREATMENT- ANTIBIOTICS
Streptococci (relatively resistant- mic. > 0.01)
PenG 4 mU q 4 hrly IV -4weeks or
Ceftriaxone 2g/d IV – 4weeks plus
Gentamicin 1mg/kg q 8hrly IV -2weeks or
Vancomycin 15mg/kg q 12 IV hrly – 4 weeks
Streptococci (moderately resistant) Gemella, nut.variants
Pen G 4-5 mU q 4hrly IV -6 weeks or
Ceftriaxone 2g/d IV – 6weeks plus
Gentamicin 1mg/kg q 8hrly IV – 6weeks
17. TREATMENT- ANTIBIOTICS
Enterococci: Pen G 4-5 mU q 4hrly IV - 4-6weeks or
Amp 2g q 4hrly IV- 4 -6weeks or
Vancomycin 15mg/Kg q 12 hrly IV - 4– 6weeks
plus
Gentamicin 1mg/kg q8hrly IV -4-6weeks.
Staphylococci (Methicillin Sensitive):
Nafcillin/Oxacillin 2gq4hrly IV 4-6 wks
plus
Gentamicin 1mg/Kg q 8 hrlyIV 3-5 days or
Ceftriaxone 2g /d IV 4-6 weeks or
Vancomycin 15mg/Kg q 12hrly IV 4-6wks
18. TREATMENT- ANTIBIOTICS
Staphylococci (Methicillin Resistant):
Vancomycin 15mg/Kg q 12hrly IV 4-6wks
Staphylococci (Prosthetic Valve) (Methicillin Sensitive):
Nafcillin/Oxacillin 2g q 4hrly IV 6-8wks plus
Gentamicin 1mg/Kg q 8 hrly IV – 2wks plus
Rifampin 300mg PO q 8hrly - 6-8wks
Staphylococci (Prosthetic Valve) (Methicillin Resistant):
Vancomycin 15mg/Kg q 12hrly IV – 6-8wks plus
Gentamicin 1mg/Kg q 8hrly IV 2wks plus
Rifampin 300 mg PO q 8hrly 6-8wks
20. TREATMENT
SURGICAL THERAPY
Moderate to severe congestive heart failure due to
valve dysfunction
Partially dehisced prosthetic valve
Persistent bacteremia despite optimal antibiotic therapy
In the absence of effective antibiotic therapy
Recurrent prosthetic valve endocarditis
Prevent septic emboli
21. PROPHYLAXIS
High risk patients only
Prosthetic valves
Prior endocarditis
Congenital Cyanotic Heart Disease
Up to Six months after repair of Congenital Heart Disease
Post cardiac transplantation
Amoxicillin 2g po 1 hr before procedure
Ampicillin 2g IV 1hr before procedure
Azithromycin 500mg po 1 hr before procedure
Cephalexin 2g po 1 hr before procedure
Clindamycin 600mg po 1hr before procedure
Ceftriaxone 1g IV 1hour before surgery
Clindamycin 600mg IV 1hour before procedure
