Endocarditis Flashcards
What is quorum sensing?
The ability to respond to cell population density by gene regulation
What is the most commonly seen type of infectious endocarditis?
Native valve endocarditis
What is the most common cause of native valve endocarditis?
S.viridans
Gram positive bacteria more commonly cause infectious endocarditis. T/F?
True
Which organism is the most common cause of IVDU endocarditis?
Staphylococcus aureus
There is a higher likelihood of gram negative and fungal infectious causes in IVDU endocarditis compared to native valve endocarditis. T/F?
True
What is the most common cause of prosthetic valve endocarditis?
Staphylococci
Which gender is more likely to get endocarditis?
Men
What are the risk factor for native valve endocarditis?
Valve abnormalities such as aortic stenosis and mitral valve prolapse
IV drug use
In the UK, what is the most common cause of aortic stenosis?
Calcification of the valve
How can rheumatic fever cause aortic stenosis?
Streptococcus progenies infection which is either not treated or only partially treated results in the formation of anti-steptolysin O antibodies which in addition to attacking the bacteria also attack the cardiac valves
Why does IVDU endocarditis primarily affect the right sided heart valves?
Blood returning from the circulation enters the right side of the heart first so this side of the heart is more exposed to drugs.
Which bacterial is most likely to cause an acute endocarditis?
S.aureus
Which bacteria is most likley to cause subacute endocarditis?
Strep. viridians
How long does the injection usually take to present in infectious endocarditis?
2 weeks
The presence of both a fever and a murmur suggests which diagnosis until proven otherwise?
Infectious endocarditis
Fever can be absent in elderly patients with endocarditis. T/F?
True
In addition to fever and murmurs, what common complaints might you expect in infectious endocarditis?
Fatigue
Malaise
What are the hallmarks of embolic disease in infectious endocarditis?
Splinter haemorrhages
Conjunctival petechiae
Septic pulmonary emboli
What are the more catastrophic effects which can occur as a result of embolism of infectious endocarditis?
Stroke
Renal infarction
Septic pulmonary emboli are more commonly seen in infectious endocarditis affecting which side of the heart?
Right side
What are the possible immunological damages that can occur due to infectious endocarditis?
Splenomegaly
Nephritis
Vasculititic lesions of the skin and eye
Finger clubbing
What. are the possible direct. tissue damages that can occur due to infectious endocarditis?
Valve destruction
valve abscess formation
Osler’s nodes can occur as late effects of infection in patients with infectious endocarditis. What are Osler’s nodes?
Painful, palpable lesions found on the hands and feet
When should a diagnosis of infectious endocarditis be considered?
All patients with s.auerus bacteraemia
IV drug users with any positive blood cultures
All patients with prosthetic valves and positive blood cultures
There is constant bacteraemia in infectious endocarditis. What is the implication of this with regard to taking blood cultures?
There is no need to wait for a fever before taking a blood culture
Blood culture samples should be taken before antibiotics are given. T/F?
True
Describe the pros and cons of trans-thoracic versus tranoesophageal echocardiograms?
Trans-thoracic is non-invasive but only has a 50\5 sensitivity
Transoesophageal is invasive but has a much higher sensitivity of 85-100%
What are the major criteria of the Duke criteria of infectious endocarditis?
Typical organism present in 2. separate blood cultures
Positive echocardiogram or new valve regurgitation
What are the minor criteria of the Duke criteria of infectious endocarditis?
Predisposition e.g. heart condition or IVDU
Fever >38
Vascular phenomenon e.g. septic emboli
Immunological phenomena e.g. Osler’s nodes
Positive blood cultures which did not meet the major criteria
Describe how the major and minor criteria of the Duke criteria can be used to determine the likelihood of infectious endocarditis.
Likely to be IE if: 2 major criteria or 1 major and 3 minor criteria or 5 minor criteria
Bacteriostatic agents are used in the treatment of infectious endocarditis. T/F?
False - bactericidal agents are used
IV therapy is given for the duration of treatment in most cases of infectious endocarditis. T/F?
True
For how long are IV antibiotics typically given in native valve endocarditis?
4 weeks
For how long are IV antibiotics typically given in prosthetic valve endocarditis?
6 weeks
What antibiotics cans be used to treat endocarditis as a result of streptococcus infection?
Benzylpenicllin +/-Gentamicin.
What antibiotics cans be used to treat endocarditis as a result of s.aureus (MSSA) infection?
Flucloxacillin +/- gentamicin
What antibiotics cans be used to treat endocarditis as a result of s.aureus (MRSA) infection?
Vancomycin +/- gentamicin
What antibiotics cans be used to treat endocarditis as a result of enterococcus infection?
Amoxicillin or vancomycin +/- gentamicin
What antibiotics cans be used to treat endocarditis as a result of CoNS infection?
Vancomycin +/- gentamicin +/- rifampicin
What are the indications for surgical intervention in infectious endocarditis?
Heart failure
Uncontrolled infection
Prevention fo embolism for large vegetations (>10mm). or following one or more embolic episodes
What signs of uncontrolled infection can indicate the need for surgical intervention in endocarditis?
Local uncontrolled infection e.g. abscess, false aneurysm, enlarging vegetation
Persisting fever and positive blood culture for more than 7-10 days
Infection caused by fungi or multi antimicrobial resistant microorganisms
What are the common clinical signs and symptoms of infective endocarditis?
Fever often associated with chills, anorexia, weight loss
Malaise, myalgia, arthralgia, night sweats
Dyspnoea
Cardiac. murmurs
Splenomegaly
Petechiae
Splinter haemorrhages
What are Janeway lesions?
Nontender erythematous mucules on the palms and soles
Janeway lesions are relatively uncommon clinical manifestation of infectious endocarditis.
What are Roth spots
Relatively uncommon clinical manifestation of infectious endocarditis
Exudative, oedematous haemorrhage retinal lesions
How should blood cultures be taken when dealing with a possible bacterial endocarditis?
3 sets of blood cultures taken from peripheral veins at different point. 10ml of blood in each bottle. Meticulous sterile technique. Taken prior to antibiotics
What is the most significant factor in identifying microorganisms from blood cultures?
The volume of blood collected
Why should taking blood culture samples for central venous catheters be avoided/
This gives a high risk of contaminants and misleading findings
Give example fo gram negative rod bacteria?
E.coli
Klebsiella
Pseudomonas
Give an example. fo a gram negative cocci bacteria
Neisseria
What bacteria are the most common contaminants in blood cultures?
Coagulase negative staphylococci
Why are gram negative bacteria found in blood culture unlikely to be contaminants?
Usually contaminants are commensal organisms from the skin which are usually gram positive
What are the two types fo alpha-haemolytic streptococci bacteria?
Streptococcus pneumoniae
Streptococcus viridans
What are the three types of beta haemolytic streptococci?
Group A. - streptococci pyogenes
Group B - streptococci agalactiae
Group C - enterococcus
Streptococci bacteria can be further classified by their ability to haemolyse blood agar. T/F?
True
