Transcript Update on Infective Endocarditis

Update on
Infective Endocarditis
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
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
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%
Mitral Valve Prolapse
and Infective Endocarditis
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18
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2
0
Male
Female
<19
20-29
30-39
40-49
Rev Infect Dis 1986;8:117-137
50-59
>60
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
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
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
Predisposing Factors
Polymicrobial Infective Endocarditis
Iv drug use
Central line
Prosthetic valve
Previous IE
Murmur
Dental procedure
Rheumatic disease
Miscellaneous
Polymicrobial Infective Endocarditis
clinical features
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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 leftsides vs pure right-sided endocarditis
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
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
Diagnostic (Duke) Criteria
• Major criteria
– positive blood culture for IE
– evidence of endocardial involvement
• Minor criteria
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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
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
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)
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)
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)
Risk for Endocarditis
• High risk
– prosthetic cardiac valve
– prior episodes of endocarditis
– complex congenital cardiac defect
– surgically constructed systemicpulmonary shunts or conduits
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
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
Treatment
• Pre-antibiotic era - a death sentence
• Antibiotic era
– microbiologic cure in majority of
patients
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
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
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
SBE Prophylaxis
Standard general prophylaxis
Unable to take oral meds
Allergic to penicilin
Allergic to penicillin and unable
to take oral medications
amoxicillin
ampicillin
clindamycin
cephalexin
azithromycin
clarithromycin
clindamycin
cefazolin
References
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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