1 INFECTIVE ENDOCARDITIS Vegetations (arrows) due to viridans streptococcal endocarditis involving the mitral valve

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INFECTIVE ENDOCARDITIS

Vegetations (arrows) due to viridans streptococcal endocarditis involving the mitral valve.

Infective endocarditis (IE) is an infection of the endocardial surface of the heart.

The intracardiac effects of this infection include severe valvular insufficiency, which may lead to congestive heart failure and myocardial abscesses. IE also produces a wide variety of systemic signs and symptoms through several mechanisms, including both sterile

and infected emboli and various

immunological phenomena.

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Acute endocarditis usually occurs when heart valves are colonized by virulent bacteria in the course of microbemia. The most common cause of acute endocarditis is Staphylococcus aureus; other less common causes are Streptococcus pneumoniae, Neisseria gonorrhoeae, Streptococcus pyogenes, and Enterococcus faecalis.

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Patients with subacute endocarditis usually have underlying valvular heart disease and are infected by less virulent organisms such as viridans streptococci, enterococci, nonenterococcal group D streptococci, microaerophilic streptococci, and Haemophilus species.

Bacteremia can result from various invasive procedures

Endoscopy Rate of 0-20% CoNS, streptococci, diphtheroids

Colonoscopy Rate of 0-20% Escherichia coli, Bacteroides species

Barium enema Rate of 0-20% Enterococci, aerobic and anaerobic gram-negative rods

Dental extractions Rate of 40-100% S viridans

Transurethral resection of the prostate Rate of 20-40% Coliforms, enterococci, S aureus

Transesophageal echocardiography Rate of 0-20% S viridans, anaerobic organisms, streptococci

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primary portals

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primary portals

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Clinical and Laboratory Features of Infective Endocarditis

Fever 80-90 % Chills and sweats 40-75 % Anorexia, weight loss, malaise 25-50 % Myalgias, arthralgias 15-30 % Back pain 7-15 % Heart murmur 80-85 % New/worsened regurgitant murmur 10-40 %

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Arterial emboli 20-50 % Splenomegaly 15-50 % Clubbing 10-20 % Neurologic manifestations

20-40 % Peripheral manifestations

(Osler's nodes, subungual hemorrhages, Janeway lesions, Roth's spots) 2-15 %

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Petechiae 10-40 % Laboratory manifestations: Anemia 70-90 % Leukocytosis 20-30 % Microscopic hematuria 30-50 % Elevated erythrocyte sedimentation

rate >90 %

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Rheumatoid factor 50 % Circulating immune complexes 65-100 % Decreased serum complement 5-40 %

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Common Peripheral Manifestations of Infective Endocarditis.Splinter hemorrhages (A) are normally seen under the fingernails. They are usually linear and red for the first-two to three days and brownish thereafter.Panel B shows conjunctival petechiae.Osler's nodes (Panel C) are tender, subcutaneous nodules, often in the pulp of the digits or the thenar eminence.Janeway's lesions (Panel D) are nontender, erythematous, hemorrhagic, or pustular lesions,

often on the palms or soles.

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Noncardiac Manifestations

Janeway’s lesions. Hemorrhagic, infarcted macules and papules on the volar fingers in a patient with S. aureus endocarditis.

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Septic vasculitis associated with bacteremia. Dermal nodule with hemorrhage and necrosis on the dorsum of a finger. This type of lesion occurs with bacteremia (e.g., S. aureus) and fungemia (e.g., Candida tropicalis).

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subconjunctival hemorrhage. Submucosal hemorrhage of the lower eyelid in an elderly diabetic with enterococcal endocarditis; splinter hemorrhages in the midportion of the nail bed and Janeway lesions were also present.

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Splinter hemorrhages, embolic Subungual hemorrhages in the midportion of the nail bed (quite different in comparison to traumatic splinter hemorrhages) was noted in several fingernails in a 60-year-old female with enterococcal endocarditis, who had associated subconjunctival hemorrhage.

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Splinter haemorrhages are linear haemorrhages lying parallel to the long axis of finger or toe nails.

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Osler's nodes. Violaceous, tender nodules on the volar fingers associated with minute infective emboli or immune complex deposition.

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Septic emboli with hemorrhage and infarction due to acute Staphylococcus aureus endocarditis.

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Vasculitis

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Clubbing. Seen in patients with chronic lung disease, cyanotic heart disease, cirrhosis and infective endocarditis.

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Infective endocarditis: metastatic infections due to emboli.

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Computed tomography of the abdomen showing large embolic infarcts in the spleen and left kidney of a patient with Bartonella endocarditis.

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The Duke Criteria for the Clinical Diagnosis of Infective Endocarditis

Positive blood culture for Infective Endocarditis Typical microorganism consistent with IE from 2 separate blood cultures, as noted below:• viridans streptococci, Streptococcus bovis, or HACEK group, or • community-acquired Staphylococcus aureus or enterococci, in

the absence of a primary focus or Microorganisms consistent with IE from persistently positive

blood cultures defined as:• 2 positive cultures of blood samples drawn >12 hours apart, or

• all of 3 or a majority of 4 separate cultures of blood (with first and last sample drawn 1 hour apart)

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MAJOR CRITERIA: Evidence of endocardial involvement Positive echocardiogram- Oscillating intracardiac mass on valve or supporting

structures or in the path of regurgitant jets or in implanted material, in the absence of an alternative anatomic explanation, or

- Abscess, or- New partial dehiscence of prosthetic valve, or New valvular regurgitation (increase or change in

preexisting murmur not sufficient)

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MINOR CRITERIA : Predisposition: predisposing heart condition or injection

drug use Fever ≥38.0◦C Vascular phenomena: major arterial emboli, septic

pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages,

Janeway lesions Immunologic phenomena: glomerulonephritis, Osler's nodes, Roth's spots, rheumatoid factor

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MINOR CRITERIA : Microbiologic 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

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Documentation of two major criteria, of one major and three minor criteria, or of five minor criteria allows a clinical diagnosis of definite endocarditis.

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INFECTIVE ENDOCARDITIS

Vegetations (arrows) due to viridans streptococcal endocarditis involving the mitral valve.

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Characteristic sites of vegetations within the heart. In the presence of aortic insufficiency, vegetations characteristically occur on the ventricular surface of the aortic valve (A) or on the chordae tendinae or papillary muscles (B). In mitral regurgitation, the vegetations characteristically are located on the atrial surface of the mitral valve (C) or at sites of jet lesions (D) on the atrial wall.

Further Classification Acute

Affects normal heart valves

Rapidly destructive

Metastatic foci Commonly Staph. If not treated,

usually fatal within 6 weeks

Subacute Often affects

damaged heart valves

Indolent nature If not treated,

usually fatal by one year

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Antibiotic Treatment for Infective Endocarditis Caused by Common

Organisms Streptococci Penicillin-susceptible streptococci, S.

bovis Penicillin G 2-3 million units IV q4h for 4 weeks Penicillin G 2-3 million units IV q4h plus

gentamicin 1 mg/kg IM or IV q8h, both for 2 weeks Ceftriaxone 2 g/d IV as single dose for 4 weeks Vancomycind 15 mg/kg IV q12h for 4 weeks

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Antibiotic Treatment for Infective Endocarditis Caused by Common

Organisms

Relatively penicillin-resistant streptococci

- Penicillin G 3 million units IV q4h for 4-6 weeks plus gentamicin 1 mg/kg IV q8h for 2 weeks

Penicillin-resistant streptococci, pyridoxal-requiring streptococci (Abiotrophia spp.)

- Penicillin G 3-4 million units IV q4h plus gentamicinc 1 mg/kg IV q8h, both for 4-6 weeks

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Indications for Cardiac Surgical Intervention in Patients with

Endocarditis Surgery required for optimal outcome Moderate to severe congestive heart failure due to valve

dysfunction Partially dehisced unstable prosthetic valve Persistent bacteremia despite optimal antimicrobial therapy Lack of effective microbicidal therapy (e.g., fungal or Brucella

endocarditis) S. aureus prosthetic valve endocarditis with an intracardiac

complication Relapse of prosthetic valve endocarditis after optimal

antimicrobial therapy Persistent unexplained fever (≥10 days) in culture-negative

prosthetic valve endocarditis

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Indications for Cardiac Surgical Intervention in Patients with

Endocarditis Surgery to be strongly considered for improved outcomea Perivalvular extension of infection Poorly responsive S. aureus endocarditis involving the aortic

or mitral valve Large (>10-mm diameter) hypermobile vegetations with

increased risk of embolism Persistent unexplained fever (≥10 days) in culture-negative

native valve endocarditis Poorly responsive or relapsed endocarditis due to highly

antibiotic-resistant enterococci or gram-negative bacilli

Prevention Approximately 15-25% of cases of IE are a consequence

of invasive procedures that produce a significant bacteremia. Because only 50% of those who developed valvular infection following a procedure were identified as being candidates for antibiotic prophylaxis, only approximately 10% of cases of IE can be prevented by the administration of preprocedure antibiotics.

Maintaining good oral hygiene is probably more effective in the overall prevention of valvular infection because gingivitis is the most common source of spontaneous bacteremias.

The American Heart Association periodically compiles recommendations for IE prophylaxis.

Documents

1 INFECTIVE ENDOCARDITIS Vegetations (arrows) due to viridans streptococcal endocarditis involving the mitral valve