Infective Endocarditis Flashcards
(33 cards)
What is infective endocarditis overall, what are the subtypes and what is its mortality and why?
- Infection of the endothelium of the heart valves
- Acute or Subacute
- Up to 25% mortality as often diagnosed late
What are the predisposing factors of infective endocarditis?
- Heart valve abnormality
- Calcification/sclerosis in the elderly
- Congenital heart disease
- Post rheumatic fever
- Prosthetic heart valve
- IV drug users
- Intravascular lines
What are the 6 stages in the pathogenesis of infective endocarditis?
- Heart valve damages
- Turbulent blood flow over roughened endothelium
- Platelets/fibrin deposited
- Bacteriaemia (may be very transient) e.g. from dental treatment
- Organisms settle in fibrin/platelet thrombi becoming a microbial vegetation
- Infected vegetations are friable and break off, becoming lodged in the next capillary bed they encounter causing abscesses or haemorrhage (may be fatal)
What valves are normally affected?
Left sided valves - mitral and aortic
What are the causative organisms of infective endocarditis (from most common to least)
- Staphylococcus aureus (38%)
- Viridans streptococci (31%)
- Enterococcus sp (8%)
- Staph epidermidis (6%)
What are the unusual organisms that can cause IE?
- Gram negatives - HACEK and non-HACEK
- Fungi
- other atypical organisms
What is the pathway of investigations if there is a clinical suspicion of IE?
What are the major dukes criteria for IE?
- Two separate positive blood cultures with typical IE microorganism(s)
- Echo evidence of valvular involvement
- New valvular regurgitation
What are the minor dukes criteria for IE?
- Predisposing heart condition / IV drug use
- Temperature >38oC
- Vascular phenomena
- Immunological phenomena
- Microbiological evidence (not major)
What infection appears as gram positive cocci in clusters when cultured?
Staphylococcus
Why do you take multiple blood cultures?
- Staph. epidermis is a skin/prosthetic material contaminant so can cause false results
- Take multiple to minimise chance of this
What is the process of identifying a species of microorganism?
- Select colony or process blood culture bottle
- Prepare target plate
- Generate MALDI-TOF profile spectrum
- Interpret data and identify species
What antimicrobial guidelines do you follow after identifying the causative organism?
Local guideline e.g. Antibiotic Man
What are the presenting features of acute endocarditis? Why?
- Patients present with overwhelming sepsis and cardiac failure
- Usually due to aggressive (virulent) organisms such as staph. aureus
What are the presenting symptoms of subacute IE?
- Fever
- Malaise
- Weight loss
- Tiredness
- Breathlessness
What are the presenting signs of subacute IE?
- Fever
- New or changing heart murmur
- Clubbing
- Splinter haemorrhages
- Splenomegaly
- Roth spots, Janeway lesions, Osler nodes
- Microscopic haematuria
What class are viridans group streptococci?
Alpha, haemolytic strep
Where are janeway lesions, roth spots and osler nodes found and how are they different?
- Janeway = palms/soles
- Roth = back of eye
- Osler = palms/soles (raised)
What are the subclasses of prosthetic valve endocarditis and what are the causes?
- Early (within 60 days) - usually infected at time of valve insertion and usually due to staph. epidermis or staph. aureus
- Late - up to many years after valve insertion, due to coincidental bactaraemi (wind range of possible organisms)
What antibiotics are given in Tayside whilst waiting on culture results if IE suspected and the patient has a prosthetic valve or suspected MRSA?
- Vancomycin & Gentamicin IV
- Rifampicin at day 3-5
What is the most common sites of IE in people who inject drugs (PWID) and what is the normal causative organism?
- Right sided endocarditis
- Tricuspid most commonly
- Usually staph aureus
What is the bacteriacidal regime for native valve IE?
Amoxicillin and gentamicin IV
What is the bactericidal regime for drug user IE?
Flucloxacillin IV
What is the specific treatment of staph. aureus?
Flucloxacillin IV
