Infective Endocarditis Flashcards
What is the definition of Infective endocarditis?
Infection of the endocardium by bacteria
What does IE commonly affect
Valvular structures (native or prosthetic) Chrodae tendineae Site of septal defects Mural endocardium
What are risk factors for native valve IE
Mitral valve disease Rheumatic heart dissease Congenital heart disease Degenerative heart disease Assymetrical septal hypertrophy IVDA Alcoholic cirrhosis Diabetes M Indwelling medical devices
Does IE have a worse prognosis in males or females?
Females
Which mitral valve disease increases the risk of IE?
Mitral valve prolapse
What congenital heart diseases increases the risk of IE?
Ventricular septal defect
Bicuspid aortic valve
Patent ductus arteriosus
What is the pathophysiology of IE from endothelial damage?
- Mechanical endothelial damage exposes ECM protein -> production of tissue factors
- Deposition of fibrin and platelets
- Forms non-bacterial thrombotic endocarditis (NBTE)
NBTE facilitate bacterial adherence and infection
What can cause damage to the endothelial valve?
Turbulent blood flow Electrode Catheters Inflammation (rheumatic carditis) Degenerative valve disease (seen with echo)
What is the venturi effect?
Constriction of part of vessel increase the velocity but reduces pressure, this can cause turbulent flow which can damage the endothelium
What is the pathophysiology of IE from endothelial inflammation?
- Endothelial inflammation -> expression of interns (B1 family)
Integrins are transmembrane proteins that bind fibrin to endothelial surface - IE pathogens carry fibronectin -> binding proteins on their surface
- Adhere to endothelium and organisms trigger active internalisation into valve endothelial cells
What is the pathophysiology of IE from bacteraemia?
Invasive procedure:
Dental procedures - perforation of oral mucosa
GU and GI surgery
IV catheters
Extra-cardiac infections
Non-invasive activities (chewing and teeth brushing)
Name 5 causative organisms
Strep viridans Staph aureus Enterococci Staphylococci (coagulase-neg) H influenzae
Actinobacillus Streptococcus bovis Fungi Coxiella burnetii, Brucella species, Culture-negative Haemphilus species, Actinobacillus,actinomycetemcomitans, Cardiobacterium hominis, eikenella corrodens and Kingella species (HACEK)
How can IE be classified?
Acute or subacute
Nidus (localisation) of infection +/- intra-cardiac material
Mode of acquisition (IVDU, healthcare or community)
Active infective endocarditis
Recurrence (relapse or reinfection)
What is an atypical presentation of IE?
Elderly or immunocompromised patients
What is an acute presentation of IE?
Fever
Embolic signs/symptoms
Decompensated HF
What is a subacute presentation of IE?
Fever
Palpitation
Immunologic/vascular phenomena
Non-specific constitutional symptoms
What are common symptoms of IE?
Fever/chills Night sweats Malaise Fatigue Anorexia Weight loss
Non-specific: Weakness Arthralgia Headache SOB
What are clinical signs of IE?
Cardiac murmur (regurgitant) Janeway lesions Osler nodes Roth spot Meningeal signs Splinter haemorrhage Cutaneous infarcts Vasculitic rash
What are Janeway lesions?
Haemorrhagic, macular, painless plaques with predilection for palms and soles
What are Osler nodes?
Small, painful nodular lesions found on the pads of fingers or toes
What investigations are carried out for IE?
Blood culture FBC U+Es Urinalysis +ve for blood ECG CXR MRI Leucocyte SPECT/CT Echo (transthoracic (TTE) +/- transoesophageal (TOE))
What do you look for in FBC?
Elevated acute inflammatory markers:
Erythrocyte sedimentation rate (ESR)
C-reactive protein (CRP)
What can an ECG show for IE?
PR interval prolongation > 0.2s
What can an CXR show for IE?
Pulmonary congestion or abscess
When to carry out TOE after a TTE echo?
If has prosthetic valve or intracardiac device
Non-diagnosis TTE
Postive TTE
If TOE negative but high suspicion, repeat TTE and/or TOE with 5-7days
What investigations for IE should be carried out if patient have a native valve?
- Repeat echo
- Imaging for embolic events
- Cardiac CT
What investigations for IE should be carried out if patient have a prosthetic valve?
- Repeat echo
- Leucocyte SPECT/CT
- Cardiac CT
- Imaging for embolic events
What are the 3 categories of IE after investigation?
Definite
Possible
Rejected
What are the 2 major criterias for 2015 Modified Duke’s Criteria?
Blood cultures positive for IE
Imaging positive for IE
What are the critierias that determine positive IE blood cultures?
Typical microorganisms of IE from 2 separate blood cultures: Strep viridans, strep bovis, HACEK grow, staph aureus
Microorganisms of IE from perisistently positive blood cultures: >2 pos. from samples 12hr apart OR all 3 or most of cultures > 4 taken 1 hr apart
Single positive blood culture for coxiella burnetti or phase I IgG antibody titre > 1:800
What are the critierias that determine positive IE in imaging?
A. Echocardiogram positive for IE: vegetation, abscess, pseudo aneurysm, valvular perforation
B: Abnormal activity around the site of prosthetic valve implantation detected by PET/CT or radiolabelled leukocytes SPECT/CT
C. Paravalvular lesions by cardiac CT
What are the 5 minor criteria?
- Prediposing heart conditions or IVDA
- Pyrexia >38
- Vascular phenomena: major arterial emolbi, intracranial haemorrhage, conjunctival haemorrhage and janeways lesions
- Immunological phenomena: oilers nodes, roth spots and rheumatoid factor
- Microbiological evidence; positive blood culture but does not meet a major
What criteria is required to diagnose definite IE?
2 major
1 major and 3 minor
5 minor
What criteria is required to diagnose possible IE?
1 major and 1 minor
3 minor
What criteria is required to diagnose rejection IE?
Resolution of endocarditis with antibiotics therapy <= 4 days
What does does treatment of IE depend on?
Whether patient has received previous antibiotic therapy
Whether the infection affects a native valve or a prosthesis (if so, was surgery early or late PVE)
The place of infection (community, nosocomial, healthcare related) and knowledge of the local epidemiology, especially for antibiotic resistance and specific culture-neg pathogens
What antibiotics are used to treat community-acquired native valves or late prosthetic valves?
Ampicillin
Flucloxacillin or oxacillin
Gentamicin
What antibiotics are used to treat early PVE or nosocomial and non-nosocomial healthcare related endocarditis?
Vancomycin
Gentamicin
Rifampin
What are patient characteristics that are poor predictors of IE?
Old
Prosthetic valve IE
Diabetes M
Comorbidity
What are clinical complications of IE which suggests poor prognosis?
Heart failure Renal failure > moderate area of ischaemic stroke Brain haemorrhage Septic shock
What are microorganisms of IE which suggest poor prognosis?
Staph aureus
Fungi
Non-HACEK
What are the preventive measures?
Strict dental hygiene Disinfection of wounds Eradication or decrease of chronic bacterial carriage: skin, urine Curative antibiotics for infection No self-medication with antibiotics Strict infection control Discourage piercing and tattooing Limit use of infusion catheters and invasive procedures
What are echocardiographic findings that are poor predictors?
L sided valve regurgitation Low LV EF PHT Large vegetations Prosthetic dysfunction Premature mitral valve closure
