Infective Endocarditis Flashcards
Definition
Infection of the endocardium (lining of the heart) resulting in damage to the cusp of the valves
Pathophysiology
- Nonbacterial thrombotic endocarditis, a sterile fibrin-platelet vegetation.
- Bacteremia (nosocomial or spontaneous) that delivers the organisms to the surface of the valve.
- Adherence of the organisms.#
- Eventual invasion of the valvular leaflets.
- Local tissue destruction and embolic phenomena.
- Secondary autoimmune effects, such as immune complex glomerulonephritis and vasculitis.
Mitral valve > aortic valve > combined mitral and aortic valve > tricuspid valve > pulmonic valve (rarely).
Mechanical prosthetic and bioprosthetic valves exhibit equal rates of infection.
Classification
-
Native valve endocarditis - 50% of cases, acute or subacute
- normal valve - identifiable risk factors - acute course
- underlying valve abnormality (mitral valve prolapse or Aortic stenosis)- subacute course
- Prosthetic valve endocarditis- 10-20%
- Rhuematic valve disease - 30%
Strongest risk factor for developing endocarditis is a previous episode of endocarditis
Cause of infective endocarditis
- Streptococcus viridans (most common cause - 40-50%)
- Staphylococcus epidermidis (especially prosthetic valves)
- Staphylococcus aureus (especially acute presentation, IVDUs)
- Streptococcus bovis is associated with colorectal cancer
- Streptococcus mitis (viridans streptococcus): following dental work
Early PVE (<2 months): Staphylococcus epidermidis.
Late PVE (>2 months): normal spectrum of organisms, except with a slight increase in Staph. aureus infections
Also rarely:
- HACEK (haemophillus, actinobacillus, cardiobacterium, eikenlla, kingella)
- Fungi: Candida
Causes of a negative culture result
- prior antibiotic therapy
- coxicella burnetti
- brucella
- HACEK
Non-infective causes of endocarditis
- SLE
- malignancy
Clinical features
Septic signs:
- FEVER+ MURMUR (note fever may be absent in elderly and murmur may be absent in tricuspid)
- Incubation period = 2 weeks (may be longer in IVDU)
- rigors, night weats, malaise, weight loss
Embolic events:
- Splinter haemorrhages
- Absecess
- janeway lesions
Immune complex deposition
- Vasculitis
- roth spots
- splinter haemorrhages
- osler nodes
Cardiac lesions:
- any new or changing pre-existing murmur
- vegetations
Osler nodes
Tender subcutaneous nodules found on distal pads of the digits - Immunological!!
Janeway lesions
Painless maculae on the palms and soles
Roth spots
retinal haemorrhages with small, clear centres
Diagnosis
- use Duke criteria
-
Blood cultures:
- do 3 sets at different times from different sites
- before antibiotics
- aseptic technique
- volume important >10mls/bottle
- Blood tests: Normochromic, normocytic anaemia, neutrophillia, high ESR
- Urinalysis: for microscopic haematuria
- CXR: Cardiomegaly
- Echocardiography: TOE(invasive, transducer in oesophagus 85-100% sensitivity), TTE (non invasive, transducer at front of chest, 50% sensitivity)
Duke’s Criteria
BE FEVER
MAJOR
- Blood cultures +ve >2 times 12hr part or persistently positive blood cultures (3>12hr apart)
- Endocardial involvement from echo
Minor
- Fever >38o
- Echo findigns that does not meet major criteria
- Vascular/ Immunological findings
- Evidence from microbiology (blood culture that doesnt meet major)
- Risk factors predisposing
How to diagnose: 2 major or 1 major and 3 minor or all 5 minor
Medical Management
- inital blind therapy
- native valve: amoxicillin (consider low-dose gentamicin)
- prosthetic valve: vancomycicn+ rifampicin+low dose gentamicin
- NVE cause by staphylococci- fluxlaxicillin
- PVE cause by staphylococci - fluxloc+ rifampicin+ low dose gent
- Endocarditis caused by fully sensitive strept- benzylpenicillin
- endocarditis cause by less sensitive strep- benzylpenicillin + low dose gent
Surgical management
- Heart failure
- uncontrollable infection
- abcess
- persisting fever + postive blood cultures >7 days
- infection caused by multi-drug resistant organisms
- prevention of embolism - embolic episode or vegetation
Complications
- congestive heart failure
- periannular abscess
- splenic abscess
- neurological complications
