Contents
Overview
Criteria for High Clinical Suspicion of IE
General Therapeutic Principles of Empiric Pharmacological Therapy
General Therapeutic Principles of Pathogen-specific Pharmacological Therapy
Principles of Surgical Treatment
Follow-Up
Diagnosis
Empiric Pharmacological Therapy
Pathogen-specific Pharmacological Therapy
Surgery
Guideline References
Overview
Infective Endocarditis (IE): An infection of the endocardial surface of the heart including infections of the large thoracic vessels & intracardiac foreign bodies characterized by the presence of vegetation which is a nidus for microorganism invasion
Native Valve Endocarditis (NVE): An endovascular microbial infection of native heart valves that may be local (cardiac) including valvular & perivalvular destruction or distal (noncardiac) due to detachment of septic vegetations w/ embolism, metastatic infection & septicemia. May also be broken down as acute & subacute; the only difference is that subacute endocarditis has a more indolent course than the acute form
Prosthetic Valve Endocarditis (PVE): An endovascular microbial infection of prosthetic heart valves (intracardiac foreign body) & may be classified as an infection likely to have been acquired perioperatively & thus being nosocomial (early PVE) or likely to have been community-acquired (late PVE). Early PVE occurs w/in 60 days of valve implantation & late PVE occurs ≥60 days after valve implantation
Characteristics of IE
- IE often presents in an occult fashion & early diagnosis depends on a high index of clinical suspicion esp in patients w/ congenital heart disease, prosthetic valves or previous IE
- The established diagnosis of IE is demonstrated by a positive blood culture & involvement of the endocardium detected during sepsis or systemic infection
- IE may also be established if there is involvement of the endocardium detected during sepsis or systemic infection but blood culture (BC) is negative
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Criteria For High Clinical Suspicion of IE
- Embolic event(s) of unknown origin
- Fever, plus:
- Positive blood culture (organism identified is typical for NVE/PVE)
- Previous history of IE, valvular or congenital heart disease
- Evidence of CHF or pulmonary embolism
- Focal or nonspecific neurological signs & symptoms
- Cutaneous (Osler, Janeway) or ophthalmic (Roth) manifestations
- Newly developed ventricular arrhythmias or conduction disturbances
- Peripheral abscesses (renal, splenic, spine) of unknown origin
- Predisposition & recent diagnostic/therapeutic interventions known to result in significant bacteremia
- Prosthetic material inside the heart
- Pulmonic infiltrations that are multifocal/rapid changing (right IE)
- Hematuria, glomerulonephritis & suspected renal infarction
- New valve lesion/regurgitant murmur
- Sepsis of unknown origin
Cardiac Risk Factors for IE
High Risk Factors
- Aortic regurgitation
- Aortic stenosis
- Coarctation of aorta
- Cyanotic congenital heart disease
- Mitral regurgitation
- Mitral stenosis w/ regurgitation
- Patent ductus arteriosus
- Previous IE
- Prosthetic heart valves
- Surgically repaired intracardiac lesion w/ residual hemodynamic abnormality
- Ventricular septal defect
Intermediate Risk Factors
- Asymmetrical septal hypertrophy
- Bicuspid aortic valve disease
- Calcific aortic sclerosis w/ minimal hemodynamic abnormality
- Degenerative valve diseases in elderly patients
- Mitral valve prolapse
- Pulmonary stenosis
- Pure mitral stenosis
- Surgically repaired intracardiac lesion w/ minimal hemodynamic abnormality <6 mth after surgery
- Tricuspid valve disease
Non-Cardiac Risk Factors Predisposing Patient to IE
- Older age
- Nonbacterial thrombotic vegetation (NBTV): Microorganisms may adhere more easily in the presence of fresh platelet thrombi associated w/ leukemia, cirrhosis of the liver, carcinomas which may cause hypercoagulability (marantic endocarditis), inflammatory bowel disease, SLE & steroid medication
- Compromised host defense typical in steroid medication & possibly in chronic alcoholism
- IVDA risk of IE is 12-fold higher than non-IVDAs
- Compromised local non-immune defense mechanism
- Found in increased transmucosal permeability in mucous membrane lesions eg chronic inflammatory bowel disease
- Reduced capillary clearance in arteriovenous fistulas of patients on chronic hemodialysis
- Increased risk or an increased frequency for bacteremia
- Patients w/ broken skin (eg DM, burns), on intensive care (eg lines, respirators), w/ polytrauma, w/ poor dental status or on hemodialysis
- Previous exposure to endocarditis-causing microorganisms
Below is the overview of disease management of Infective Endocarditis:

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General Therapeutic Principles of Empiric Pharmacological Therapy
- Counting days of duration of therapy should start on the 1st day on which BCs were negative in cases in which initial BCs were positive
- At least 2 sets of BCs should be obtained every 24-48 hr until bloodstream infection is cleared
- For patients w/ NVE who undergo valve resection w/ prosthetic valve replacement, the post-op treatment should be the one recommended for NVE, not for PVE
- If the resected tissue is culture positive, then the entire course of therapy is recommended after valve resection
- If the resected tissue is culture negative, then treatment should be given less the number of days of treatment administered for NVE before valve replacement
- If combination antimicrobial therapy is used, then the agents should be administered close together to improve synergistic killing effect
- Antibiotic prophylaxis has been limited to patients undergoing an invasive dental procedure in whom exists a history of IE, prosthetic valve, a heart transplant w/ abnormal heart valve function, or congenital heart disease w/ the following: Unrepaired cyanotic congenital heart disease, congenital heart defect completely repaired w/ prosthetic material or device for the 1st 6 mth post procedure, or repaired congenital heart disease w/ residual defects
- Patients w/ prosthetic valves are at the highest risk of developing IE
- Recommended regimens include the standard Amoxicillin, Ampicillin if unable to take PO meds, & Clindamycin (PO or IV), Clarithromycin, Cefazolin or Cefalexin if w/ penicillin allergy
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General Therapeutic Principles of Pathogen-Specific Pharmacological Therapy
- Counting days of duration of therapy should start on the 1st day on which BCs become negative in cases in which initial BCs were positive
- At least 2 sets of BCs should be obtained every 24-48 hr until blood stream infection is cleared
- For patients w/ NVE who undergo valve resection w/ prosthetic valve replacement, the post-op treatment should be the one recommended for NVE, not for PVE
- If the resected tissue is culture positive, then the entire course of therapy is recommended after valve resection
- If the resected tissue is culture negative, then treatment should be given less the number of days of treatment administered for NVE before valve replacement
- If combination antimicrobial therapy is used, then the agents should be administered close together to improve synergistic killing effect
The therapeutic goal is to produce bactericidal levels of drugs at the infected site for a max period of time
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Principles of Surgical Treatment
- Combined medical & surgical therapy for IE can decrease mortality among patients who have CHF, perivalvular invasive disease, or uncontrolled infection despite maximal antimicrobial therapy
- The decision to perform surgery & its timing is dependent upon the cardiac & systemic complications caused by the infection, the microorganism’s virulence & the response to antimicrobial therapy
- The optimal time to perform surgery is before severe hemodynamic disability or spread of the infection to perivalvular tissue occurs
- CHF is the strongest indication for surgery in IE
Below is the overview of treatment of Infective Endocarditis:

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Follow-Up
- Daily exam including temp & periodic blood tests to monitor for signs of infection
- Temp should normalize w/in 5-10 days w/ uncomplicated IE
- Continue to monitor for cardiac murmurs, BP, signs of HF & embolism in the CNS, lungs, spleen & skin
- Secondary infections in joint & spine may occur
- C-reactive protein (CRP) decreases rapidly during 1st or 2nd wk of therapy but may stay slightly elevated for 4-6 wk or longer
- Persistently high CRP typically means an inadequately controlled infection
- Normalization of WBC should also occur w/in 1-2 wk
- Persistently elevated WBC indicates active infection
- Monitor renal function
- Good oral & overall hygiene are recommended for risk reduction
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Infective Endocarditis Symptoms▶
Version: 07 Apr 2015
Guideline References:
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