Infective endocarditis Flashcards
What is the strongest risk factor for infective endocarditis?
The strongest risk factor for developing infective endocarditis is a previous episode of endocarditis.
The following types of patients are affected:
- previously normal valves (50%, typically acute presentation)
- the mitral valve is most commonly affected
- rheumatic valve disease (30%)
- prosthetic valves
- congenital heart defects
- intravenous drug users (IVDUs, e.g. typically causing tricuspid lesion)
- others: recent piercings
What is the most common cause of infective endocarditis?
- Staphylococcus aureus is now the most common cause of infective endocarditis. Staphylococcus aureus is also particularly common in acute presentation and IVDUs
- Coagulase-negative Staphylococcus epidermidis most common cause of endocarditis in patients following prosthetic valve surgery, usually the result of perioperative contamination. After 2 months the spectrum of organisms which cause endocarditis return to normal (i.e. Staphylococcus aureus is the most common cause)
- Streptococcus viridans still accounts for around 20% of cases. Commonly found in the mouth and dental plaque :. linked with poor dental hygiene or following a dental procedure
- Non-infective: systemic lupus erythematosus (Libman-Sacks), malignancy: marantic endocarditis
What are culture negative causes of infective endocarditis?
- Prior antibiotic therapy
- Coxiella burnetii
- Bartonella
- Brucella
- HACEK: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella
How do you diagnose infective endocarditis?
Infective endocarditis diagnosed if:
- pathological criteria positive, or
- 2 major criteria, or
- 1 major and 3 minor criteria, or
- 5 minor criteria
What is a pathological criteria?
- Positive histology or microbiology of pathological material obtained at autopsy or cardiac surgery (valve tissue, vegetations, embolic fragments or intracardiac abscess content)
What are major criteria?
Positive blood cultures
- 2 positive blood cultures showing typical organisms consistent with infective endocarditis, such as Streptococcus viridans and the HACEK group, or
- Persistent bacteraemia from two blood cultures taken > 12 hours apart or three or more positive blood cultures where the pathogen is less specific such as Staph aureus and Staph epidermidis, or
- Positive serology for Coxiella burnetii, Bartonellaspecies or Chlamydia psittaci, or
- Positive molecular assays for specific gene targets
Evidence of endocardial involvement
- Positive echocardiogram (oscillating structures, abscess formation, new valvular regurgitation or dehiscence of prosthetic valves), or
- New valvular regurgitation
What are minor criteria?
- Predisposing heart condition or intravenous drug use
- Microbiological evidence does not meet major criteria
- Fever > 38ºC
- Vascular phenomena: major emboli, splenomegaly, clubbing, splinter haemorrhages, Janeway lesions, petechiae or purpura
- Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots
What are poor prognosis factors for infective endocarditis?
- Staphylococcus aureus infection (see below)
- Prosthetic valve (especially ‘early’, acquired during surgery)
- Culture negative endocarditis
- Low complement levels
What does mortality in IE depend on?
Mortality according to organism:
- Staphylococci - 30%
- Bowel organisms - 15%
- Streptococci - 5%
What are indications for surgery in IE?
- Severe valvular incompetence
- Aortic abscess (often indicated by a lengthening PR interval)
- Infections resistant to antibiotics/fungal infections
- Cardiac failure refractory to standard medical treatment
- Recurrent emboli after antibiotic therapy
What is the management of IE?
Which procedures do NOT require prophylaxis (according to NICE)?
- Dental procedures
- Upper and lower gastrointestinal tract procedures
- Genitourinary tract; this includes urological, gynaecological and obstetric procedures and childbirth
- Upper and lower respiratory tract; this includes ear, nose and throat procedures and bronchoscopy
What do NICE guidelines suggest about antimicrobial therapy due to GI/GU procedure?
If a person at risk of infective endocarditis is receiving antimicrobial therapy because they are undergoing a gastrointestinal or genitourinary procedure at a site where there is a suspected infection they should be given an antibiotic that covers organisms that cause infective endocarditis
