5. Endocarditis - Infective Endocarditis (IE) Infective...

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Unformatted text preview: Infective Endocarditis (IE) Infective Endocarditis Definition: infection of the endocardial Definition: surface of the heart or valves, or both Characteristic lesion is a friable vegetation laden with microorganisms Infective Endocarditis Classification based on: on: 1. Presentation acute - fluminant, death within days fluminant, to 6 wks subacute - death in 6 wks to 3 months chronic - death > 3 months Infective Endocarditis 2. Etiologic agent determines: course of disease likelihood of previous ht disese appropriate antimicrobial therapy Infective Endocarditis Incidence: 1 case per 1000 hospital admissions no change in past 30 years >50% of patients >50 years male : female = 2:1 Mortality: uniformly fatal prior to antibiotic era 10 - 20% fatality rate Frequency of Heart Valves Involved in IE Heart Valve Mitral alone Aortic alone Mitral + aortic Tricuspid alone Pulmonary alone Percent affected 28 - 45 5 - 36 0 - 35 0-6 <1 80% left sided only, 12% right sided only, 8% both Predisposing Conditions for Infective Endocarditis Condition Percentage of Cases Rheumatic Ht Disease 15% Congenital Ht Disease 5 - 25% Degenerative Cardiac Disease 30 - 40% IVDU (Intravenous Drug User) 30% Prosthetic valves 5% Mitral valve prolapse 10% Other, pacemaker wires, shunts, fistulas, etc.) Varies Incidence of Bacteremia After Various Procedures Procedure / Manipulation Dental Extraction Periodontal surgery Chewing candy or paraffin Tooth brushing Oral irrigation device Upper airway Bronchoscopy (rigid scope) Tonsillectomy Nasotracheal suctioning 18 - 85 32 - 88 17 - 51 0 - 26 27 - 50 15 28 - 38 16 Percentage of positive blood cultures Everett et al. Medicine 1977 Etiologic Agents in Infective Endocarditis Agent Streptococci viridans enterococci other Staphylococci S. aureus CNST Gram negative bacilli Fungi Miscellaneous bacteria Culture negative Percentage of Cases 60 - 80 30 - 40 5 - 18 15 - 25 20 - 30 10 - 27 1-3 1.5 - 13 2-4 <5 < 5 - 24 What is Streptococcus viridans? Streptococcus viridans is a pseudotaxonomic term for a large group of generally non-pathogenic, commensal streptococcal bacteria that are either hemolytic and produce a green (hence the name viridans) coloration on blood agar plates, or non-hemolytic Causes of "Culture - negative" Endocarditis Fastidious organisms HACEK group nutritionally variant strep. Intracellular pathogens chlamydia Q fever rickettsiae Prior antibiotics Right sided Fungal Chronic disease (>3 mos) mos) Endothelium of valves trauma turbulence metabolic changes Platelet-Fibrin Deposition Platelet- Mucous Membranes or Other Colonized Tissue Local ecological factors, bacteriocins, IgA protease bacteriocins, bacterial adherence Trauma Nonbacterial Thrombotic Endocarditis (NBTE) Bacteremia Adherence Colonization bacterial division, fibrin deposition, platelet aggregation, extracellular proteases, protection from neutrophils Mature Vegetation Infective Endocarditis Clinical features due to: i) Infectious process on involved valve(s) ii) Continuous bacteremia with metastatic foci of infection iii) Bland or septic embolization iv) Immunologically mediated phenomena (eg. immune complexes) eg. v) Non-specific effects of chronic infection Non- Infective Endocarditis Clinical Features: incubation period < 2 weeks [bacteremic event (eg. dental (eg. extraction) to onset of symptoms] symptoms to diagnosis: 5 weeks Clinical Manifestations of Infective Endocarditis 1. Symptoms nonspecific; highly variable fever (80 9 - 0%), chills, weakness, anorexia, weight loss, etc. Infective Endocarditis Streptococcal >80% have underlying ht disease <10% mortality subacute course Staphylococcal (80-90% due to S. aureus) (80aureus) majority have no underlying ht disease 40% mortality fulminant, acute course fulminant, 2. Signs - - heart murmur (85%), embolic phenomenon (>50%), splenomegaly (20 6 - 0%), retinal lesions (5%) skin manifestations (20 5 - 0%), others highly variable Infective Endocarditis Enterococcal >40% have no underlying ht disease high mortality (20%) due to antibiotic resistance subacute course Infective Endocarditis Laboratory features: 1. Hematologic parameters (Non-specific) (Non2. Blood cultures 3. Echocardiography Infective Endocarditis Blood Cultures: bacteremia continuous, low grade positive in 70 - 95% of cases yield affected by prior antibiotics, organism involved 3 sets (detects 99%) essential for proper management Infective Endocarditis Echocardiography: transthoracic or transesophageal sensitivity 50 - 90% cannot exclude IE; false pos. rare vegetation suggests increased risk of: systemic emboli congestive heart failure death (especially aortic valve) Infective Endocarditis in IVDU acute infection accounts for 60% of hospital admissions; IE in 5 - 10% have no underlying heart disease S. aureus 60%, streptococci 16% predilection to infect tricuspid valve 80% of pts. are 20 - 40 yrs. old; M:F = 5:1 staphylococcal endocarditis less severe in IVDUs; mortality 2 - 6% IVDUs; Prosthetic Valve Endocarditis (PVE) early PVE occurs within 60 days of surgery occurs in 2 - 3% of patients; early PVE vs. late PVE CNST > Viridans Strep. > S. aureus mortality: 41% early PVE, 21% late PVE Therapy for Infective Endocarditis Medical: guided by organism and in vitro susceptibility prolonged (minimum 4 wks) parenteral antibiotics, not oral combination therapy for synergy bactericidal antibiotics laboratory monitoring Therapy for Infective Endocarditis Indications for surgery: intractable heart failure major systemic emboli failure of optimal antibiotics to sterilize blood and / or vegetation fungal endocarditis most prosthetic valve IE myocardial abscess large vegetation on echocardiogram Prevention of Infective Endocarditis Considerations: no placebo - controlled human studies most cases of IE of oral origin are not caused by dental procedures; poor oral hygiene is biggest cause AHA regimens have had numerous failures recent antibiotic therapy may lead to resistant organisms; use different antibiotic for prophylaxis Prevention of Infective Endocarditis Considerations: risk of antibiotics toxic effects may be greater than risk of IE incidence of IE after dental procedure in a non-medicated at risk pt is about 1:115,000 non oral regimens preferred for high-risk pts high do not "err on the positive side" of antibiotic prophylaxis Dental Procedures Prevention of Endocarditis Considerations: 1. Dental procedure 2. Cardiac condition Prophylaxis Recommended Procedures known to cause gingival or mucosal bleeding, including professional cleaning Prophylaxis Not Recommended Procedures not likely to induce gingival bleeding eg. simple adjustment of orthodontic appliances or fillings above the gum line Injection of local intraoral anesthetic American Heart Association, July 1997, Circulation Cardiac Condition Prophylaxis Recommended Prosthetic cardiac valves Previous bacterial endocarditis Most congenital cardiac defects Rheumatic valvular disease Acquired valve dysfunction Hypertrophic cardiac myopathy MVP with regurgitation American Heart Association, July 1997, Circulation Prophylaxis Not Recommended Previous bypass surgery Mitral Valve Prolapse (MVP) without regurgitation Physiologic, innocent heart murmurs Cardiac pacemaker, implanted defibrillator Antimicrobial Prophylaxis for Prevention of Endocarditis Situation 1. Standard 2. Unable to take oral medication Agent Amoxicillin 2 gm 1 hr before Ampicillin 2 gm iv/im 30 min before or Clindamycin 600 mg iv 30 min before American Heart Association, July 1997, Circulation ...
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This note was uploaded on 05/09/2010 for the course LMP 232 taught by Professor Crandall during the Spring '10 term at University of Toronto- Toronto.

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