update on infective endocarditis
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Update on Infective Endocarditis. Larry Baddour, MD University of Tennessee. Pathogenesis. Disruption of the endocardial layer as a complication of abnormal blood flow associated with underlying cardiac defect - PowerPoint PPT PresentationTRANSCRIPT
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Update onInfective Endocarditis
Larry Baddour, MD
University of Tennessee
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Pathogenesis
• Disruption of the endocardial layer as a complication of abnormal blood flow associated with underlying cardiac defect
• Bacterium-endothelium interaction with bacterial attachment and invasion of endothelial cells
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Epidemiology
• Underlying valvular abnormality predisposing to infective endocarditis– rheumatic fever
a common cause in the past– mitral valve prolapse
currently represents the most common underlying cardiac abnormality
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mitral valve prolapse
• risk for infective ednocarditis is 5x-8x • mitral regurgitation increases the risk• leaflet redundancy with myxomatous
degeneration is a frequent finding• age <20 , female predominate
age >20 , male accounts for 60%age >50 , male accounts for 68%
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Mitral Valve Prolapse and Infective Endocarditis
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Rev Infect Dis 1986;8:117-137
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Coagulase-negative Staphylococci
• can produce native-valve endocarditis in mitral valve prolapse
• usually subacute, difficult to diagnose, and disregarded as a contaminant
• delay in diagnosis and treatment may account for the severe complications– myocardial abscess formation– valvular insufficiency requiring valve surgery– death
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Prosthetic Heart Valve
• positive blood culture in hospitalized patients with underlying prosthetic valves can be a harbinger of endocarditis
• 43% patients with nosocomial bacteremia or fungemia had prosthetic valve infection
• a serious complication
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IV Drug Use
• Recurrent
• Polymicrobial
• Staph aureus accounts for the majority of cases of endocarditis
• tricuspid valve, either alone or in combination, us most often infected
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Predisposing Factors Polymicrobial Infective Endocarditis
Iv drug use
Central line
Prosthetic valve
Previous IE
Murmur
Dental procedure
Rheumatic disease
Miscellaneous
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Polymicrobial Infective Endocarditisclinical features
• IV drug use is the predominant risk factor• younger age (mean 36.5 years)• 2/3 were male• right-sided cardiac involvement in > 60%• streptococci more frequent than S. aureus• 1/3 of patients died • mortality rate is 4x higher for pure left-
sides vs pure right-sided endocarditis
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Diagnostic (Duke) Criteria
• Definitive infective endocarditis– pathologic criteria
• microorganisms or pathologic lesions: demonstrated by culture or histology in a vegetation, or in a vegetation that has embolized, or in an intracardiac abscess
– clinical criteria (see below) • two major criteria, or one major and three
minor criteria, or five minor criteria
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Diagnostic (Duke) Criteria
• Possible infective endocarditis– findings consistent of IE that fall short of
“definite”, but not “rejected”
• Rejected– firm alternate Dx for manifestation of IE– resolution ofmanifestations of IE, with
antibiotic therapy for 4 days
– no pathologic evidence of IE at surgery or autopsy, after antibiotic therapy for 4 days
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Diagnostic (Duke) Criteria
• Major criteria– positive blood culture for IE– evidence of endocardial involvement
• Minor criteria– predisposition (heart condition or IV drug use)– fever of 100.40F or higher– vascular or immunologic phenomena– microbiologic or echocardiographic evidence
not meeting major criteria
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Duke’s Major Criteria
• positive blood culture for IE– typical microorganism (strep viridans, strep
bovis, HACEK group, staph aureus or enterococci in the absence of a primary locus) for endocarditis from two separate blood cultures
– persistently positive blood culture from:• blood cultures drawn more than 12 hr apart, or• all of 3 or a majority of 4 or more separate blood
cultures, with first and last drqwn at least 1 hr apart
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Duke’s Major Criteria
• Evidence of endocardial involvement– positive echocardiogram for endocarditis
• oscillating intracardiac mass on valve or supporting structure, or in the path of regurgitant jets, or on implanted material, in the absence of an alternate anatomic explanation
• abscess• new partial dehiscence of prosthetic valve
– new valvular regurgitation (increase or change in pre-existing murmur not sufficient)
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Duke’s Minor Criteria
• predisposition (predisposing heart condition or iv drug use)
• fever of 100.40F or higher• vascular phenomena (major arterial
emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctive hemorrhages, Janeway lesions)
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Duke’s Minor Criteria
• immunologic phenomena (glomerulonephritis, Osler’s nodes, Roth spots, rheumatoid factor)
• microbiologic evidence (positive blood culture not meeting major criteria or serologic evidence of active infection with organism consistent with IE)
• echocardiogram (consistent with IE but not meeting major criteria)
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Risk for Endocarditis
• High risk– prosthetic cardiac valve– prior episodes of endocarditis– complex congenital cardiac defect– surgically constructed systemic-
pulmonary shunts or conduits
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Risk for Endocarditis
• Moderate risk– patent ductus arteriosus– VSD, primum ASD– coarctation of the aorta– bicuspid aortic valve– hypertrophic cardiomyopathy– acquired valvular dysfunction– MVP with mitral regurgitation
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Risk for Endocarditis
• Low risk– isolated secundum atrial septal defect– ASD, VSD, or PDA >6 months past
repair– “innocent” heart murmur by
auscultation in the pediatric population– “innocent” heart murmur by
echocardiography in adult patients
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Treatment
• Pre-antibiotic era - a death sentence
• Antibiotic era– microbiologic cure in majority of
patients
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New Treatments
• Right-sided infective endocarditis due to methicillin-susceptible S aureus (MSSA) in IV drug users– 2-wk therapy with a penicillinase-resistant
penicillin and an aminoglycoside– 2-wk monotherapy with IV cloxacillin– short-term therapy is inappropriate if
complicated by ostomyelitis, meningitis, myocardial abscess, or concomitant left-sided involvement
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New Treatments
• Highly penicillin-susceptible Streptococcus viridans or bovis– Once-daily ceftriaxone for 4 wks
• cure rate > 98%• easily administered as outpatient, avoid
hospitalization, offers significant cost savings
– Once-daily ceftriaxone 2 g for 2wks followed by oral amoxicillin qid for 2 wks
– Once-daily ceftriazone and netilmicin for 2 wks
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New Treatments
• Prosthetic valve endocarditis due to fluconazole-susceptible Candida species– many are due to bloodstream invasion– chronic oral suppressive therapy with
fluconazole for inoperable disease
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SBE Prophylaxis
Standard general prophylaxis amoxicillin
Unable to take oral meds ampicillin
Allergic to penicilin clindamycin
cephalexin
azithromycin
clarithromycin
Allergic to penicillin and unable clindamycin
to take oral medications cefazolin
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References
• Prevention of bacterial endocarditis. Recommended by the American Heart Association. Dajani AS, Taubert KA, Wilson W, et al. Circulation 1997;96:358-366
• New Criteria for diagnosis of infective endocarditis: Utilization of specific echocardiographic findings. Durack DT, Lukes AS, Bright DK, et al. Am J Med 1994;96:200-209
• Antibiotic treatment of adults with infective endocarditis due to strptococci, enterococci, staphlococci, and HACEK microorganisms. Wilson WR, Karchmer AW, Dajani AS. JAMA 1995;274:1706-1713