Endocarditis, Infective

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Basics

Description

  • Infective endocarditis (IE) is a noncontagious infection of the inner layer of the heart which includes valves (native or prosthetic), interventricular septum, septal defects, intracardiac devices, chordae tendineae, and mural endocardium. IE occurs worldwide and is generally fatal if left untreated.
  • System(s) affected: cardiovascular, endocrine/metabolic, hematologic/lymphatic, immunologic, pulmonary, renal/urologic, skin/exocrine, neurologic
  • Synonym(s): bacterial endocarditis; subacute bacterial endocarditis (SBE); acute bacterial endocarditis (ABE)

Epidemiology

More common in males (3:1). 50% of cases occur in individuals >50 years of age.

Incidence
  • 1.5–3% incidence 1 year after prosthetic valve replacement; 3–6% 5 years postreplacement
  • Increasing incidence of cardiovascular device–related infections due to higher frequency of implantable devices, especially in the elderly.
  • Can be community- or hospital-acquired
  • Most commonly affects the mitral valve and aortic valve (left-sided, increased pressure and turbulent flow)

Etiology and Pathophysiology

IE is most commonly caused by a nonbacterial thrombus that forms and adheres to an endocardial surface, coupled with a bacterial source sufficient to seed the thrombus. This can occur from direct bacterial invasion or valvular trauma.

  • Native valve endocarditis
    • Acute: Staphylococcus aureus; Streptococcus groups A, B, C, G; Streptococcus pneumoniae; Staphylococcus lugdunensis; Enterococcus spp. (gram-positive); Haemophilus influenzae or parainfluenzae; Neisseria gonorrhoeae (gram-negative)
    • Subacute: α-hemolytic streptococci (viridans group strep), Streptococcus bovis, Enterococcus spp., S. aureus, Staphylococcus epidermidis (gram-positive); HACEK organisms: Haemophilus aphrophilus or paraphrophilus, Actinobacillus (Aggregatibacter) actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae
  • Intravenous drug abuse endocarditis (IVDA) (most commonly tricuspid valve): S. aureus, Enterococcus spp. (gram-positive); Pseudomonas aeruginosa, Burkholderia cepacia, other bacilli (gram-negative); Candida spp.
  • Prosthetic valve endocarditis
    • Early (≤12 months after valve implantation): S. aureus, S. epidermidis (gram-positive); gram-negative bacilli; fungi: Candida spp., Aspergillus.
    • Late (>12 months after valve implantation): α-hemolytic streptococci, S. aureus, Enterococcus spp., S. epidermidis (gram-positive); Candida spp., Aspergillus spp.
  • Culture-negative endocarditis: 10% of cases; Bartonella quintana (homeless); Brucella spp., fungi, Coxiella burnetii (Q fever), Chlamydia trachomatis, Chlamydophila psittaci, HACEK organisms
  • Device-related endocarditis: coagulase-negative staphylococci or S. aureus

Risk Factors

  • Injection drug use, IV catheterization, certain malignancies (colon cancer), poor dentition/infection, chronic hemodialysis, age >60 years, male sex
  • High risk with:
    • Prosthetic cardiac valve, implantable devices (pacemaker, automatic implantable-cardioverter defibrillator [AICD]), total parenteral nutrition
    • Previous IE
    • Congenital heart disease (CHD): unrepaired cyanotic CHD, including palliative shunts and conduits; repaired CHD with prosthetic device during the first 6 months; repaired CHD with residual defects at or near prosthetic site; cardiac transplant with valvulopathy (1)[B]

General Prevention

  • Good oral hygiene
  • Antibiotic prophylaxis is only recommended in patients with a high risk of adverse outcomes if IE were to occur (1)[B]—prosthetic heart valve (determine material used for repair), history of IE, unrepaired cyanotic CHD, transplant with abnormal valvular function (see “Risk Factors”). Administer 30 to 60 minutes prior to the procedure (exception vancomycin which should be administered 120 minutes prior to the procedure).
  • Procedures requiring prophylaxis
    • Oral/upper respiratory tract: any manipulation of gingival tissue or periapical region of teeth or perforation of the oral mucosa (1)[B]; invasive respiratory procedures involving incision; or biopsy of the respiratory mucosa. Amoxicillin 2 g PO 30 to 60 minutes before procedure or ampicillin 2 g IV/IM are first-line prophylactic choices. For penicillin-allergic patients, use clindamycin 600 mg IV, or cephalexin 2 g PO, or azithromycin/clarithromycin 500 mg PO, or cefazolin/ceftriaxone 1 g IV/IM 30 minutes before procedure. Pediatric doses are amoxicillin 50 mg/kg PO (max 2 g), cephalexin 50 mg/kg PO (max 2 g), clindamycin 20 mg/kg PO (max 600 mg), and ampicillin or ceftriaxone 50 mg/kg (maximum 1 g) IM/IV.
    • GI/GU: Only consider coverage for Enterococcus (with penicillin, ampicillin, piperacillin, or vancomycin) for patients with an established infection undergoing procedures (1)[B].
    • Cardiac valvular surgery or placement of prosthetic intracardiac/intravascular materials: perioperative cefazolin 1 to 2 g IV 30 minutes preoperative or vancomycin 15 mg/kg (maximum 1 g) (penicillin-allergic patients) 60 minutes preoperative (1)[B]
    • Skin/soft tissue: incision and drainage of infected tissue; use agents active against skin pathogens (e.g., cefazolin 1 to 2 g IV q8h or vancomycin 15 mg/kg q12h; max 1 g) if penicillin-allergic or if methicillin-resistant S. aureus (MRSA) suspected.

Commonly Associated Conditions

Most patients with IE have preexisting conditions such as structural heart disease, valvular disease, CHD, prosthetic heart valves, transcatheter aortic valve replacement, intravascular devices, and/or cardiac implantable electronic devices. Patients undergoing chronic hemodialysis have an increased occurrence of IE.

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Basics

Description

  • Infective endocarditis (IE) is a noncontagious infection of the inner layer of the heart which includes valves (native or prosthetic), interventricular septum, septal defects, intracardiac devices, chordae tendineae, and mural endocardium. IE occurs worldwide and is generally fatal if left untreated.
  • System(s) affected: cardiovascular, endocrine/metabolic, hematologic/lymphatic, immunologic, pulmonary, renal/urologic, skin/exocrine, neurologic
  • Synonym(s): bacterial endocarditis; subacute bacterial endocarditis (SBE); acute bacterial endocarditis (ABE)

Epidemiology

More common in males (3:1). 50% of cases occur in individuals >50 years of age.

Incidence
  • 1.5–3% incidence 1 year after prosthetic valve replacement; 3–6% 5 years postreplacement
  • Increasing incidence of cardiovascular device–related infections due to higher frequency of implantable devices, especially in the elderly.
  • Can be community- or hospital-acquired
  • Most commonly affects the mitral valve and aortic valve (left-sided, increased pressure and turbulent flow)

Etiology and Pathophysiology

IE is most commonly caused by a nonbacterial thrombus that forms and adheres to an endocardial surface, coupled with a bacterial source sufficient to seed the thrombus. This can occur from direct bacterial invasion or valvular trauma.

  • Native valve endocarditis
    • Acute: Staphylococcus aureus; Streptococcus groups A, B, C, G; Streptococcus pneumoniae; Staphylococcus lugdunensis; Enterococcus spp. (gram-positive); Haemophilus influenzae or parainfluenzae; Neisseria gonorrhoeae (gram-negative)
    • Subacute: α-hemolytic streptococci (viridans group strep), Streptococcus bovis, Enterococcus spp., S. aureus, Staphylococcus epidermidis (gram-positive); HACEK organisms: Haemophilus aphrophilus or paraphrophilus, Actinobacillus (Aggregatibacter) actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae
  • Intravenous drug abuse endocarditis (IVDA) (most commonly tricuspid valve): S. aureus, Enterococcus spp. (gram-positive); Pseudomonas aeruginosa, Burkholderia cepacia, other bacilli (gram-negative); Candida spp.
  • Prosthetic valve endocarditis
    • Early (≤12 months after valve implantation): S. aureus, S. epidermidis (gram-positive); gram-negative bacilli; fungi: Candida spp., Aspergillus.
    • Late (>12 months after valve implantation): α-hemolytic streptococci, S. aureus, Enterococcus spp., S. epidermidis (gram-positive); Candida spp., Aspergillus spp.
  • Culture-negative endocarditis: 10% of cases; Bartonella quintana (homeless); Brucella spp., fungi, Coxiella burnetii (Q fever), Chlamydia trachomatis, Chlamydophila psittaci, HACEK organisms
  • Device-related endocarditis: coagulase-negative staphylococci or S. aureus

Risk Factors

  • Injection drug use, IV catheterization, certain malignancies (colon cancer), poor dentition/infection, chronic hemodialysis, age >60 years, male sex
  • High risk with:
    • Prosthetic cardiac valve, implantable devices (pacemaker, automatic implantable-cardioverter defibrillator [AICD]), total parenteral nutrition
    • Previous IE
    • Congenital heart disease (CHD): unrepaired cyanotic CHD, including palliative shunts and conduits; repaired CHD with prosthetic device during the first 6 months; repaired CHD with residual defects at or near prosthetic site; cardiac transplant with valvulopathy (1)[B]

General Prevention

  • Good oral hygiene
  • Antibiotic prophylaxis is only recommended in patients with a high risk of adverse outcomes if IE were to occur (1)[B]—prosthetic heart valve (determine material used for repair), history of IE, unrepaired cyanotic CHD, transplant with abnormal valvular function (see “Risk Factors”). Administer 30 to 60 minutes prior to the procedure (exception vancomycin which should be administered 120 minutes prior to the procedure).
  • Procedures requiring prophylaxis
    • Oral/upper respiratory tract: any manipulation of gingival tissue or periapical region of teeth or perforation of the oral mucosa (1)[B]; invasive respiratory procedures involving incision; or biopsy of the respiratory mucosa. Amoxicillin 2 g PO 30 to 60 minutes before procedure or ampicillin 2 g IV/IM are first-line prophylactic choices. For penicillin-allergic patients, use clindamycin 600 mg IV, or cephalexin 2 g PO, or azithromycin/clarithromycin 500 mg PO, or cefazolin/ceftriaxone 1 g IV/IM 30 minutes before procedure. Pediatric doses are amoxicillin 50 mg/kg PO (max 2 g), cephalexin 50 mg/kg PO (max 2 g), clindamycin 20 mg/kg PO (max 600 mg), and ampicillin or ceftriaxone 50 mg/kg (maximum 1 g) IM/IV.
    • GI/GU: Only consider coverage for Enterococcus (with penicillin, ampicillin, piperacillin, or vancomycin) for patients with an established infection undergoing procedures (1)[B].
    • Cardiac valvular surgery or placement of prosthetic intracardiac/intravascular materials: perioperative cefazolin 1 to 2 g IV 30 minutes preoperative or vancomycin 15 mg/kg (maximum 1 g) (penicillin-allergic patients) 60 minutes preoperative (1)[B]
    • Skin/soft tissue: incision and drainage of infected tissue; use agents active against skin pathogens (e.g., cefazolin 1 to 2 g IV q8h or vancomycin 15 mg/kg q12h; max 1 g) if penicillin-allergic or if methicillin-resistant S. aureus (MRSA) suspected.

Commonly Associated Conditions

Most patients with IE have preexisting conditions such as structural heart disease, valvular disease, CHD, prosthetic heart valves, transcatheter aortic valve replacement, intravascular devices, and/or cardiac implantable electronic devices. Patients undergoing chronic hemodialysis have an increased occurrence of IE.

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