Infective Endocarditis

Pathogenesis – 4 mechanisms

(1) Previously damaged cardiac valve (endothelium) or a hemodynamic situation in which a "jet effect" is present

high risk Þ prosthetic hart valves, aortic valve disease, mitral insufficiency, patent ductus arteriosus, ventricular septal defect, coarctation of the aorta, marfan’s syndrome, Hx of endocarditis, cyanotic CHD

medium risk Þ mitral valve prolapse with murmur, pure mitral stenosis, tricuspid valve disease, pulmonary valve disease, asymmetric septal hypertrophy, calcific aortic sclerosis, bicuspid aortic valve

low risk Þ atrial septal defects, atherosclerotic plaques, coronary artery disease, pacemakers

(2) Sterile fibrin-platelet thrombus, "Nonbacterial Thrombotic Endocarditis (NBTE)"

Trauma, turbulence, metabolic changes to valvular endothelium Þ platelet-fibrin vegetation Þ colonized by bugs Þ enlarges by more platelet-fibrin deposition Þ bugs are "protected" from the phagocytic cells of the body Þ require prolonged administration of bactericidal antibiotics

(3) Bacteremia

incidence of bacteremia associated with various procedures Þ chewing hard candy (20%); brushing teeth (40%); oral cavity prophylaxis (40%); single tooth extraction (18-85%); urethral surgery (67%)

if you have bad teeth and have a tooth extracted, 75% chance of having bugs floating around in your blood

(4) Agglutinating antibody for the infecting organism

virulent streptococci are more sticky than most bugs thus are most common in this type of infection
due to antibiotics, the mortality of this infection has gone down

rheumatic heart disease incidence was very high, now it is not as common

Clinical Manifestations – 4 mechanisms

(1) Infectious process on the involved valve or endocardial surface

(2) Embolization

(3) Metastatic infection secondary to constant bacteremia

(4) Deposition of abnormal globulins, circulating immune complexes

Symptoms of endocarditis Þ fever, chills, weakness, dyspnea, sweats, anorexia, weight loss, malaise, cough, skin lesion, stroke, N/V, headache, myalgia, edema, chest pain, abdominal pain, coma, hemoptysis, back pain

Signs of endocarditis Þ fever (90%), heart murmur (85%), skin manifestations (Osler’s nodes, splinter hemorrhages, petechiae, Janeway lesions), embolic phenomena, splenomegaly, septic complications, mycotic aneurysms, clubbing, retinal changes (Roth spots), renal failure

Etiologic Agents

Most common overall Þ gram-positive cocci – streptococci (60-80%), staphylococci (20-35%)

Most common acute Þ S. aureus, Strep Pneumoniae, Strep pyogenes, N. gonorrheae Þ damage to valves < 1week

Most common subacute Þ "viridians" Þ night sweats, cough, sneaks up on you in a couple weeks

Narcotic-associated endocarditis Þ S. aureus, Ps. Aeruginosa, Candida albicans

Infection seen at a younger age

Surgery is always necessary for cure of Candida endocarditis
rarely have underlying heart disease

Right side more commonly infected
symptoms: fever, pleuritic chest pain, nodular fluffy pneumonia on X-ray

Prosthetic valve endocarditis Þ skin bugs most infective

Diagnosis

Positive blood culture over time with an organism that normally causes endocarditis; anemia; Ý ESR; C-reactive protein; proteinuria; microscopic hematuria; positive rheumatoid factor; cryoglobulinemia

Echo – may provide evidence of vegetations on heart valves; represents a relative indication for surgery

Duke criteria

Major criteria Þ typical blood culture and positive echocardiogram

Minor criteria Þ predisposition, fever, vascular phenomena, immunologic phenomena, suggestive echocardiogram, suggestive microbiologic findings

Treatment

adequate treatment requires prolonged administration (usually 4-6 weeks) of bactericidal parenteral antibiotics to which the microorganisms is sensitive – oral therapy is unreliable and not recommended

the ideal antimicrobial regimen for endocarditis is completely and rapidly bactericidal

penicillins for a prolonged period of time