Introduction
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
Acute:
- 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)
Subacute:
- Low-grade fever
Signs of carditis
- Finger clubbing
- Arthralgia
- Splenonegaly
- Osler’s nodules
- Janeway lesions
- Roth spots
Differential diagnoses
- Myocarditis
- Rheumatic heart disease
Complications
- Cardiac failure
- Destruction of heart valves
- Systemic embolism (could be infective)
Investigations
- 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)
Plus:
- Gentamicin 60-80 mg intravenously 12 hourly for 2 weeks.
Following bacteriological confirmation institute appropriate antimicrobial therapy
Staphylococci:
- 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
Enterococci:
- Amoxicillin 2 gm intravenously 4 hourly; intravenously; Gentamicin 60-80 mg 12 hourly
Candida:
- Systemic antifungals
Notable adverse drug reactions
- Penicillin: rashes, anaphylaxis
- Gentamicin: nephropathy
- Monitor patients on gentamicin and
vancomycin carefully
Prevention
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:
Amoxicillin
- 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
month:
Azithromycin
- 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:
Amoxicillin
- 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.
Or:
- 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
induction- 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:
Vancomycin
- Adult: 1g intravenously over at least 100minutes
Plus
Gentamicin
- 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