Infective Endocarditis

Etiology and sources of infection

A consequence of 2 factors

• Presence of organism in blood stream• Abnormal cardiac endothelium facilitating

adherence and growth.

• Aortic and mitral valves are most commonly involved in infective endocarditis apart from intravenous drug users in whom right sided lesions are more common.

Culture negative Endocarditis

• Coxiella burnetti• Bortenella sp.• Chlamydia sp.• Legionella• Prior antibiotic therapy.

Clinical features

High clinical suspicion if….

Diagnostic criteria(Modified Duke’s Criteria)

Major criteria:• A positive blood culture for IE. Typical

organism growing in 2 cultures in absence of a primary focus.

• A persistently positive blood culture• A positive serological test for Q fever.• ECHO evidence-mass, abscess, dehiscence.• New valvular regurgitation.

Minor criteria:

• Predisposition: predisposing heart condition or intravenous drug use.

• Fever: temperature ≥ 38°C (100.4°F).

• Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, conjunctival haemorrhages, Janeway’s Lesion.

• Immunologic phenomena: glomerulonephritis, Osler’s nodes, Roth’s spots, rheumatoid factor.

• Microbiological evidence: a positive blood culture but not meeting a major criterion as noted above, or serological evidence of an active infection with an organism that can cause infective endocarditis.

• Echocardiogram: findings consistent with infective endocarditis but not meeting a major criterion as noted above.

The diagnosis of infective endocarditis is definite when: 1. A microorganism is demonstrated by culture of a

specimen from a vegetation, an embolism or an intracardiac abscess

2. Active endocarditis is confirmed by histological examination of the vegetation or intracardiac abscess

3. Two major clinical criteria, one major and three minor criteria, or five minor criteria are met.

ECHO

• TTE-high specificity. Sensitivity 60-75%.• TOE-high sensitivity >90%.• A negative echocardiogram does not exclude

a diagnosis of endocarditis.

Treatment

• Blood cultures should be taken prior to empirical antibiotic therapy.

• Antibiotic treatment should continue for 4–6 weeks.

• Serum levels of gentamicin and vancomycin need to be monitored to ensure adequate therapy and prevent toxicity.

Causes of persistent fever• Most patients with infective endocarditis should respond

within 48 hours of initiation of appropriate antibiotic therapy.

If persistent fever consider:• perivalvular extension of infection and possible abscess

formation.• Drug reaction (the fever should promptly resolve after drug

withdrawal)• Nosocomial infection (i.e. venous access site, urinary tract

infection)• Pulmonary embolism (secondary right-sided endocarditis

or prolonged hospitalization).

Antibiotic prophylaxis

Possible questions.

Name the organisms associated with the following locations/situations causing IE:

• Dental disease or procedures.• Prolonged indwelling vascular catheters.• Gut and perineum• Bowel malignancy• Native and prosthetic valve endocarditis-early

and late.• Soft tissue infection

• IE in IVDU-name the organism, site, Rx.• Name the organisms with negative culture for

IE.• The following are high clinical suspicion for IE

except?• The following are major criterion for IE

except?

Treatment choices for the following clinical situation:• Clinical endocarditis, culture results awaited, no

suspicion of staphylococci.• Suspected staphylococcal endocarditis (IVDU,

recent intravascular devices or cardiac surgery, acute infection)

• Streptococcal endocarditis• Enterococcal endocarditis• Staphylococcal endocarditis

• A person treated for IE has persistent fever after 48 hours of treatment. What are the possible explanation for this?