Infective endocarditis Flashcards
What are the common causes of native valve endocarditis?
- Staphylococcus aureus (most common for native and prosthetic/device IE)
- Viridans steptococcus (2nd most common native IE)
- Staphyloccus epidermis (2nd most common for prosthetic IE)
- enterococci
- streptococcus bovi
- other streptococci
- Coxiella burnetiid (exposure to infected animals e.g. sheep, goat, cow)
- Aspergillus, Candida (risk factors: IVDU, patients in ICU with multiple antibiotics)
- HACEK group (gram negative): Haemophilus, Aggregatibacter, Cardiobacterium hominis, Eikenella corrodens, and Kingella
- Group A strep (rheumatic fever)
What is community associated IE?
IE that develops in the absence of recent contact with a healthcare setting, with diagnosis established within 48 hours of hospital admission
What is healthcare associated IE?
IE that develops in the context of recent contact with a healthcare setting, with onset of symptoms ≥ 48 hours after hospitalization
What is nosocomial IE?
diagnosis of IE made > 72 hours after admission in patients with no evidence of IE on admission or IE that develops within 60 days of a previous hospital admission during which there was risk for bacteraemia or IE
What are the risk factors for IE?
Cardiac
- History of IE: will have higher risk of IE again
- Structural / valvular / congenital heart disease
- Prosthetic heart valve
Non‐cardiac - IVDU (intravenous drug use) Long‐standing intravascular device (e.g. peripheral cannula in chronic HD patient) - Immunosuppression (e.g. HIV) - Chronic HD - HIV infection - Poor dentition/dental infection - Age >60 yo, M - Liver abscess
What are the symptoms of IE?
- Fever is most common symptom (90%), a/w chills, LOA, LOW
- Other common symptoms: malaise, headache, myalgias, arthralgias, night sweats, abdominal pain, and dyspnoea (can be very non-specific)
What are the signs of IE?
Splenomegaly
Cutaneous manifestations, e.g. petechiae, splinter haemorrhages (but note that neither their presence nor location are diagnostic of IE, as they are commonly found in otherwise normal patients)
Uncommon manifestations, but are highly suggestive of IE:
- Janeway lesions: painless (non-tender) erythematous nodules on palms and plantar surfaces (reflect microabscesses w/ neutrophil infiltration of capillaries)
- Osler nodes: tender tall (palpable) violaceous nodules on toes and fingers, and/or thenar and hypothenar eminences
- Roth spots: a retinal lesion showing exudative oedematous haemorrhage with pale centre
- Osler nodes and Roth spots probably represent the sequelae of vascular occlusion by microthrombi leading to localized immune-mediated vasculitis (Ag-Ab complex deposition)
What are the complications of IE?
Cardiac complications : Valvular insufficiency, heart failure, others
Neurologic complications (e.g. focal neurological deficits, AMS): Embolic stroke, intracerebral haemorrhage, brain abscess, others
Septic emboli
- Infarction of kidney (AKI), spleen, other organs
- In right-sided endocarditis, septic pulmonary emboli may be seen
Metastatic infection e.g. vertebral osteomyelitis, septic arthritis, splenic or psoas abscesses
Systemic immune reaction (Ag-Ab complex deposition) e.g. glomerulonephritis (GN) (microscopic haematuria on UFEME/UA)
What are the investigations required for IE? ?
Blood (FBC, ESR/CRP, RhF)
- Raised ESR, CRP
- Normochromic normocytic anaemia
- Positive rheumatoid factor (RhF)
Urine (dipstick, UFEME)
- Microscopic haematuria
- Proteinuria
- +/- pyuria
- Red cell casts –> indicative of GN –> minor diagnostic criterion for IE
Blood c/s (cornerstone of microbiological dx of IE)
- ≥ 3 sets (increases yield to 96-98% of bacteraemia), 20 mL per blood c/s, from separate venepuncture sites, - F/U blood c/s every 48-72 hours after commencing abx, till bacteraemia cleared
- Always consider fungi, as these do not grow on routine blood c/s
2D echocardiography (2DE) (mainstay of cardiac imaging for dx of IE)
- transthoracic echocardiography (TTE) is the first diagnostic test; absence of vegetation on TTE does not preclude the diagnosis of IE
- Transoesophageal echocardiography (TOE/TEE) has higher sensitivity than TTE and is better for detection of cardiac complications such as abscess, leaflet perforation, and pseudoaneurysm
CXR: Evaluate for septic pulmonary emboli, infiltrate (+/- cavitation), congestive heart failure, potential alternative causes of fever and systemic symptoms
EC: Baseline ECG, as part of the initial evaluation for all patients with suspected IE, with subsequent telemetry monitoring or serial ECG
Dental evaluation: Focus on periodontal inflammation, pocketing around teeth, and dental caries that may result in pulpal infection and subsequent abscess
What is considered definite IE?
Pathologic criteria
- Pathologic lesions: Vegetation or intracardiac abscess demonstrating active endocarditis on histology, OR
- Micro-organism: Demonstrated by culture or histology of a vegetation or intracardiac abscess
Clinical criteria
- 2 major clinical criteria, OR
- 1 major and 3 minor clinical criteria, OR
- 5 minor clinical criteria
What is considered possible IE?
- 1 major and 1 minor clinical criteria, OR
* 3 minor clinical criteria
What is considered rejected IE?
- A firm alternate diagnosis is made, OR
- Resolution of clinical manifestations occurs after ≤ 4 days of antibiotics, OR
- No pathologic evidence of infective endocarditis is found at surgery or autopsy after antibiotic therapy for 4 days or less, OR
- Clinical criteria for possible or definite IE not met
What is the major criterior for IE?
Positive blood c/s for IE (1 of following)
1) Typical microbes consistent with IE from 2 separate blood cultures OR
- Staphylococcus aureus
- Viridans streptococci
- Streptococcus bovis (aka Group D Strep)
- HACEK group
- Community-acquired enterococci in the absence of a primary focus
2) Persistently positive blood cultures OR
- For organisms that are typical causes of IE: at least 2 positive blood cultures from blood samples drawn > 12 hours apart
- For organisms that are more commonly skin contaminants: 3 or a majority of ≥ 4 separate blood cultures (with first and last drawn at least 1 hour apart)
3) Single positive blood culture for Coxiella burnetii or phase I IgG antibody titre > 1:800*
Evidence of endocardial involvement (1 of following)
1) 2DE positive for IE
- Vegetation (oscillating intracardiac mass on a valve or on supporting structures, in the path of regurgitant jets, or on implanted material, in the absence of an alternative anatomic explanation), OR
- Abscess, OR
- New partial dehiscence of prosthetic valve
2) New valvular regurgitation
- Increase in or change in pre-existing murmur not sufficient
What is the minor criteria for IE?
Predisposition: IVDU, presence of predisposing heart condition (prosthetic heart valve or a valve lesion associated with significant regurgitation or turbulence of blood flow)
Fever (T ≥ 38)
Vascular phenomena: Major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, conjunctival haemorrhages, or Janeway lesions
Immunologic phenomena: Glomerulonephritis, Osler nodes, Roth spots, or rheumatoid factor
Microbiologic evidence
- Positive blood cultures that do not meet major criteria, OR
- Serologic evidence of active infection with organism consistent with IE
What are the antibiotics used for IE?
Native: IV penicillin/ cloxacillin +/‐ IV genta. If allergic / severe/ MRSA then IV vanco. Gram +ve and Gram ‐ve Cover! +/‐ Change to MRSA Cover
Prosthetic valve: IV vanco/ IV genta x6/52
IVDU: IV cloxacillin/ IV genta. If allergic/severe then IV cefazolin
Note: * add IV genta (or other aminoglycosides) for synergistic effect if R; otherwise does not work alone
