Update on Infective Endocarditis

1
Update onInfective Endocarditis
2
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

3
Epidemiology

• Underlying valvular abnormality predisposing to
  infective endocarditis
• rheumatic fevera common cause in the past
• mitral valve prolapsecurrently represents the
  most common underlying cardiac abnormality

4
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 lt20 , female predominateage gt20 , male
  accounts for 60age gt50 , male accounts for 68

5
Mitral Valve Prolapse and Infective Endocarditis
Male
Female
Number of cases
Rev Infect Dis 19868117-137
6
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

7
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

8
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

9
Predisposing Factors Polymicrobial Infective
Endocarditis
10
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 gt 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

13
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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Dukes 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

15
Dukes 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)

16
Dukes 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)

17
Dukes Minor Criteria

• immunologic phenomena (glomerulonephritis,
  Oslers 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 gt6 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

22
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

23
New Treatments

• Highly penicillin-susceptible Streptococcus
  viridans or bovis
• Once-daily ceftriaxone for 4 wks
• cure rate gt 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

25
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 199796358-366
• New Criteria for diagnosis of infective
  endocarditis Utilization of specific
  echocardiographic findings. Durack DT, Lukes AS,
  Bright DK, et al. Am J Med 199496200-209
• Antibiotic treatment of adults with infective
  endocarditis due to strptococci, enterococci,
  staphlococci, and HACEK microorganisms. Wilson
  WR, Karchmer AW, Dajani AS. JAMA
  19952741706-1713