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 <20 , female predominateage >20 , male accounts for 60%age >50 , male accounts for 68%

5. Mitral Valve Prolapse and Infective Endocarditis Male Female Number of cases Rev Infect Dis 1986;8:117-137

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 > 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

11. 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

12. 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

14. 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

15. 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)

16. 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)

17. 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)

18. Risk for Endocarditis • High risk • prosthetic cardiac valve • prior episodes of endocarditis • complex congenital cardiac defect • surgically constructed systemic-pulmonary shunts or conduits

19. 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

20. 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

21. 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 > 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

24. 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

26. 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