Endocarditis, Infective

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  • An infection of the valvular (primarily) and/or mural (rarely) endocardium
  • 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)


  • Incidence rose in the United States from 11/100,000 in 2000 to 15/100,000 in 2011.
  • 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

Etiology and Pathophysiology

  • ABE: Staphylococcus aureus; Streptococcus groups A, B, C, G; Streptococcus pneumoniae; Staphylococcus lugdunensis; Enterococcus spp. (gram-positive); Haemophilus influenzae or parainfluenzae; Neisseria gonorrhoeae (gram-negative)
  • SBE: 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
  • Endocarditis in IV drug abusers (tricuspid valve): S. aureus, Enterococcus spp. (gram-positive); Pseudomonas aeruginosa, Burkholderia cepacia, other bacilli (gram-negative); Candida spp.
  • Early prosthetic valve endocarditis (<60 days after valve implantation): S. aureus, S. epidermidis (gram-positive); gram-negative bacilli; fungi: Candida spp., Aspergillus spp.
  • Late prosthetic valve endocarditis (>60 days after valve implantation): α-hemolytic streptococci, 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; Abiotrophia (formerly vitamin B6deficient streptococci); use of antibiotics prior to blood cultures
  • Device-related endocarditis: coagulase-negative staphylococci or S. aureus

Risk Factors

  • Injection drug use, IV catheterization, certain malignancies (colon cancer), poor dentition, chronic hemodialysis
  • High risk with:
    • Prosthetic cardiac valve, implantable devices (pacemaker, automatic implantable-cardioverter defibrillator [AICD]), total parenteral nutrition
    • Previous infective endocarditis (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 for high-risk cardiac conditions (1)[B]—prosthetic heart valve, history of endocarditis, transplant with abnormal valvular function, CHD (see “Risk Factors”).
  • 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 merit prophylaxis. Amoxicillin 2 g PO (if penicillin allergic, clindamycin 600 mg 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: 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.

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