Infective endocarditis & other cardiac infections Flashcards
(51 cards)
what is a blood culture normally?
sterile
what is a potentially life-threatening situation that can occur in the bloodstream?
i.e. what is meant by bacteraemia?
what happens if this life threatening situation is NOT treated promptly?
- presence of bacteria in bloodstream (bacteraemia or septicaemia)
= presence of bacteria in the bloodstream
= patient may develop septic shock and die
what 3 question should you ask yourself if there is a positive culture?
1) What is the usual HABITAT of the organism?
2) what DISEASES is this organism associated with?
3) what is the optimum ANTIMICROBIAL management required?
what is infective endocarditis?
= infection of endothelium of the heart valves which is life threatening
what are the 2 types infective endocarditis can be?
1) acute
2) sub-acute
what are 4 predisposing factors for infective endocarditis?
1) heart valve abnormality
2) prosthetic heart valve
3) Intra-venous drug users
4) intra-vascular lines
what are 3 possible heart valve abnormalities that could act as predisposing factors for infective endocarditis?
1) calcification/sclerosis in elderly
2) congenital heart disease
3) post rheumatic fever
what pathological change happens to the heart valves in infective endocarditis?
= heart valves are damaged
what happens to blood flow in infective endocarditis?
= turbulent blood flow over roughed endothelium
what is pathologically deposited in infective endocarditis?
= platelets/fibrin is deposited
what pathological thing might happen in the blood stream in infective endocarditis?
= bacteraemia (may be very transient)
e.g. from dental treatment
where does the bacteria organisms in infective endocarditis settle and thus what do they become?
- organism settle in fibrin/platelet thrombi
BECOMING
= a microbial vegetation
what can happen to the infected vegetations when they become friable and break off in infective endocarditis?
= they break off
= becoming lodged in next capillary bed they encounter
= causing abscesses or haemorrhage
- may be fatal
what side of the heart is usually affected?
and thus what 2 valves are most usually affected?
= left side of heart
= mitral and aortic valves
what are the 4 organisms causing endocarditis native valve?
from most common to least
1) staphylococcus aureus
2) viridan’s streptococci
3) enterococcus sp
4) staph epidermidis
what are 3 branches of unusual organisms causing endocarditis?
1) atypical organisms
2) gram-negatives
3) fungi
give examples of atypical organisms that are unusual organisms in causing endocarditis?
- bartonella
- coxiella burnetii
- chlamydia
- legionella
- mycoplasma
- brucella
give examples of gram negative organisms that are unusual organisms in causing endocarditis?
1) HACEK organisms
- haemophilus spp
- aggregatibacter spp
- cardiobacteriium
- eikenella sp
- kingella sp.
2) non-HACEK
what is the major criteria required to diagnose infective endocarditis?
1) 2 separate positive blood cultures with microorganisms typical for infective endocarditis: viridans, streptococci, streptococcus bovid, HACEK group, staphylococcus aureus
2) echocardiogram of endocardial involvement
- typical valvular lesions: vegetation, abscess or new partial dehiscence of prosthetic valve
3) new valvular regurgitation
what is the minor criteria for diagnosing infective endocarditis?
1) predisposition heart conditions or IV drug user
2) temperature greater than 38degrees
3) vascular phenomenon
4) immunological phenomenon
5) microbiological evidence: positive blood culture but not meeting major criteria
what is the gram positive cocci in clusters called?
= staph
what is the most common coagulase-negative staphylococcus?
staphylococcus epidermidis
how do you most commonly get the bacteria staphylococcus epidermidis?
- skin contaminants
BUT - can infect prothetic material e.g. intra-vascular line infections, prosthetic heart valves
what is an example of another skin contaminate?
= corynebacterium sp
