Infective endocarditis Flashcards
IE: Definitions
Infection of endovascular structures of the heart by pathogen
IE: risk factors
Strongest: previous episode of endocarditis
- Age > 60 years
- Male sex
- Intravenous drug use - predisposition to Staph. aureus infection and right-sided valve disease e.g. tricuspid endocarditis
- Poor dentition and dental infections
IE: comorbid conditions
Valvular disease (Rheumatic heart disease, mitral valve prolapse, aortic valve disease and other abnormalities)
Congenital heart disease e.g. bicuspid aortic valve, pulmonary stenosis, ventricular septal defect
Prosthetic valves
Intravascular devices e.g. central catheters, shunts
Haemodialysis
HIV infection
IE: common organisms (in order of incidence)
- Staph. aureus
- Strep. viridans (poor dental hygiene)
- Enterococci
- Coagulase negative staphylococci e.g. Staph. epidermidis
- Strep. bovis - often in patients with colonic lesions, e.g. IBD or carcinoma
- Fungi
- HACEK organisms - Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella
IE: symptoms
Fever is the most common symptom
-Anorexia
-Weight loss
-Headache
-Myalgia
-Arthalgia
-Night sweats
-Abdominal pain
-Cough
-Pleuritic pain
IE: signs
Murmurs are also common. A patient with a fever and new murmur should always raise the suspicion of infective endocarditis.
- Janeway lesions - nontender macules on palms and soles
- Osler nodes - tender subcutaneous nodules on the finger pads and toes
- Roth spots - exudative haemorrhagic retinal lesions with pale centres
- Microscopic haematuria and glomerulonephritis
- Splinter haemorrhages
- PR prolongation or complete AV block - sign of aortic root abscess
PR prolongation or complete AV block in patient with fever and new murmur
IE –> think aortic root abscess
IE: complications
- Acute valvular insufficiency –> heart failure
- Neurologic complications e.g. stroke (esp if mitral valve affected), abscess, haemorrhage (mycotic aneurysm)
- Embolic complications causing infarction of kidneys, spleen or lung
- Infection e.g. osteomyelitis, septic arthritis
IE: investigations
- ECG
- Chest X-ray
- Blood tests: FBC, U&E, LFT, CRP
At least 3 sets of blood cultures should be taken at different times from various sites.
1st line imaging –> TTE
(Most sensitive –> TOE)
Dukes Criteria for IE: major
Blood culture positive for IE
Typical microorganisms consistent with IE from 2 separate blood cultures
Microorganisms consistent with IE from persistently positive blood cultures (>= 2 blood cultures drawn > 12 hours apart)
Single positive blood culture for Coxiella burnetti or positive antibody titre
Imaging positive for IE
Echocardiogram positive for IE e.g. vegetation, abscess, partial dehiscence of prosthetic valve, new valvular regurgitation
Abnormal activity around site of prosthetic valve implantation on PET-CT
Paravalvular lesions on cardiac CT
Dukes Criteria for IE: minor
- Predisposition e.g. predisposing heart condition or intravenous drug use
- Fever > 38.0°C
- Vascular phenomena e.g. arterial emboli, infarcts, mycotic aneurysms, intracranial or conjunctival haemorrhages, Janeway lesions
- Immunological phenomena e.g. glomerulonephritis, Osler’s nodes, Roth’s spots, rheumatoid factor
- Microbiological evidence e.g. blood culture not meeting major criteria, or serological evidence of active infection with organism consistent with IE
How does Duke’s criteria affect IE management
Definite IE - two major criteria, one major + three minor criteria, or all five minor criteria
IE management
long term IV antibiotics
IE management: initial blind therapy
Native: Amoxicillin
- If MRSA, severe sepsis or pen allergy: vancomycin + low-dose gentamicin
Prosthetic: Vancomycin + rifampicin + low-dose gentamicin
IE management: native valve endocarditis caused by staphylococci
Flucloxacillin
If penicillin allergic or MRSA –> vancomycin + rifampicin
