Infective Endocarditis


Infective endocarditis, also called bacterial endocarditis, is an infection caused by bacteria that enter the bloodstream and settle in the heart lining, a heart valve or a blood vessel.

It is a microbial infection of the endocardium and diseased heart valves (rheumatic heart disease, congenital heart disease, shunts, and prosthetic valves).

It may be acute or sub-acute.
Some acute cases occur in normal valves in intravenous drug users or may be part of systemic illness.

Sub-acute form usually occurs on diseased valves.

Causative organisms include:

  • Streptococci
  • Staphylococci,
  • Enterococci;
  • Haemophilus
  • Actinobacillus,
  • Cardiobacterium,
  • Eikenella, and Kingella species (‘Hacek Organisms)

Clinical features


  • High fever with rigors
  • Delirium
  • Shock
  • Development of new murmurs
  • Severe cardiac failure
  • Abscesses may form in many parts of the body (e.g. brain)


  • Low-grade fever

Signs of carditis

  • Finger clubbing
  • Arthralgia
  • Splenonegaly
  • Osler’s nodules
  • Janeway lesions
  • Roth spots

Differential diagnoses

  • Myocarditis
  • Rheumatic heart disease


  • Cardiac failure
  • Destruction of heart valves
  • Systemic embolism (could be infective)


  • Full Blood Count and differentials;
  • ESR
  • Urinalysis; urine microscopy
  • Blood cultures X 3 (the yield is higher at the time of pyrexia)
  • ECG
  • Chest X-ray
  • Echocardiography

Treatment objectives

  • Stop the infection
  • Prevent coagulation disorders
  • Treat cardiac failure

Non-drug treatment

  • Bed rest
  • Low salt diet

Drug treatment

Initiate therapy (culture results awaited) with:

  • Benzylpenicillin 7.2 g daily by slow
    intravenous injection or intravenous infusion in 6 divided doses for 4-6 weeks. May be increased up to 14.4 g daily if necessary (e.g. in endocarditis)


  • Gentamicin 60-80 mg intravenously 12 hourly for 2 weeks.

Following bacteriological confirmation instituteĀ appropriate antimicrobial therapy


  • Flucloxacillin: 250 mg – 2 g intravenously every 6 hours for 4-6 weeks
  • Vancomycin: 1 gm intravenously 12 hourly;
  • Gentamicin 60-80 mg intravenously 12 hourly for 2 weeks


  • Amoxicillin 2 gm intravenously 4 hourly; intravenously; Gentamicin 60-80 mg 12 hourly


  • Systemic antifungals

Notable adverse drug reactions

  • Penicillin: rashes, anaphylaxis
  • Gentamicin: nephropathy
  • Monitor patients on gentamicin and
    vancomycin carefully


Prophylactic antibiotics for patients at risk who are undergoing:

1. Dental procedures

1A. Under local or no anaesthesia, for those who have NOT had endocarditis, and have NOT received more than a single dose of penicillin in the last one month:


  • Adult: 3g orally 1 hour
    before procedure
  • Child under 5 years: 750 mg orally 1 hour before procedure; 5-10 years: 1.5g

For penicillin-allergic patients or patients
who have received more than a single
dose of a penicillin in the previous one


  • Adult: 500 mg orally one hour before procedure
  • Child
    • under 5 years: 200 mg orally;
    • 5 – 10 years: 300 mg.

1B. Patients who have had endocarditis:

Amoxicillin plus gentamicin intravenously as for procedures under general anaesthesia (see below)

1C. Dental procedures under general anaesthesia, and no special risk:


  • Adult: 1 g intravenously at induction of anaesthesia; mg orally 6 hours later
  • Child under 5 years: a quarter of adult dose; 5 – 10 half adult dose.


  • Adult: 3g orally 4 hours before induction, then 3g as soon as possible after the procedure
  • Child under 5 years: a quarter of adult dose; 5 – 10 half adult dose

1D. Special risk, e.g. previous infective
endocarditis, or patients with prosthetic valves:

Amoxicillin plus gentamicin intravenously

  • Adult: 1 g amoxicillin plus gentamicin at induction 120 mg
    • Then oral amoxicillin 500 mg 6 hours after procedure
  • Child under 5 years: a quarter of adult dose of plus 2 mg/kg gentamicin intravenously at

    • 5 – 10 years: half adult dose for Amoxicillin; 2 mg/kg gentamicin

Patients who are penicillin-allergic or have received more than a single dose of a penicillin in the last one month:


  • Adult: 1g intravenously over at least 100minutes



  • Adult: 120 mg intravenously – Given at induction or 15 minutes before procedure Child under 10 years:
    Vancomycin 20 mg/kg; gentamicin 2 mg/kg

Genito-urinary tract manipulation
As for special risk patients undergoing
dental procedures under general anaesthesia

Obstetrics, gynaecological and
gastrointestinal procedures.

As for genitourinary tract manipulation

Leave a Comment