Endocarditis, Myocarditis and Pericarditis Flashcards
What is bacteraemia?
The presence of viable bacteria in the blood stream
What is the old name for bacteraemia?
Septicaemia
What is endocarditis?
The endovascular inflammation of cardiovascular structures, usually involving the cardiac valves
What is myocarditis?
An inflammatory process leading to acute, subacute or chronic injury to the myocardium
What is pericarditis?
Inflammation of the pericardium
What are some forms of testing that can be carried out on blood cultures?
Haemolysis
Coagulase testing
Gram staining
MALDI-TOF
What is the main coagulase positive bacteria?
Staphylococcus aureus
What is the minimum number of blood cultures required in endocarditis?
3, as the more blood that is taken, the higher the sensitivity
What are some bacteria that will NOT grow on agar?
Bartonella sp
Coxiella burnetti
Chlamydia sp
Legionella sp
Mycoplasma sp
Brucella sp
What is another name for Coxiella burnetti infection?
Q fever
Where is someone most likely to contract Coxiella burnetti?
During the birthing of livestock
Where is someone most likely to contract Brucella?
From goats
What is the mnemonic for slow growing bacteria?
HACEK
What are the HACEK bacteria?
H - Haemophilus sp
A - Aggregatibacter sp
C - Cardiobacterium sp
E - Eikenella sp
K - Kingella sp
What are some common bacteria that infect wound sites and implantable devices?
Staphylococcus epidermidis
Staphylococcus aureus
Corynebacterium sp
Proprionibacterium sp
How long after the removal of an ICED should blood cultures be taken?
48 - 72 hours
What can form on the heart valves as a result of infective endocarditis?
Vegetations
How does infective endocarditis increase the risk of stroke?
Vegetations are friable and so can form septic emboli which can pass into the carotid arteries
Describe the pathogenesis of endocarditis?
Damage to a heart valve due to hypertension or turbulent blood causes formation of platelet and fibrin rich clots on the endocardium
Bacteraemia can then allow for the deposition of bacteria in the clot, forming a vegetation
What are some common causes of damage to the heart valves, therefore increasing the risk of endocarditis?
Calcification
Congenital conditions
Rheumatic fever
What are some risk factors for infective endocarditis?
Heart valve damage
Prosthetic heart valves
IV drug users
Dental damage or work
Intravascular lines
What are the most common organisms in infective endocarditis?
Staphylococcus aureus
Streptococcus viridans group
Enterococcus sp
Staphylococcus epidermidis
What effect will staphylococcus aureus have on blood agar?
It will cause a gold ring to form
What are some common examples of Viridans group streptococci?
Strep. mitis
Strep. sanguinis
Strep. mutans
Strep. salivarius
How are Viridans group streptococci likely to enter the blood stream
They are oral commensal bacteria so enter due to poor oral hygiene, during dental procedures or in IV drug users who lick the needle tip
What is the most common bacteria that infects those with prosthetic heart valves?
Staphylococcus epidermidis
What are the most common bacteria that infects those who inject drugs?
Candida
Staphylococcus aureus
What is the most commonly affected region in people who inject drugs?
The right side of the heart, most commonly the tricuspid valve
How are non-growing bacteria tested for in infective endocarditis?
Serology, which tests for the presence of antibodies
What are some tests that may be required in the diagnosis of infective endocarditis?
≥ 3 blood cultures
Echocardiography
Serology
What criteria is used for the diagnosis of infective endocarditis?
Modified Duke criteria
How many points are there in the modified Duke criteria?
7: 2 major (BE) and 5 minor (TIMER)
What are the points of the modified Duke criteria?
B - Blood cultures positive for major bacteria
E - Echocardiography shows vegetation
T - Temperature high (Fever)
I - Immunological signs
M - Microbiology suggestive of minor bacteria
E - Embolic phenomenon
R - Risk factors
What is meant by a positive blood result for major bacteria in the Duke criteria?
2 or more positive cultures for one of the following bacteria:
- Streptococcus viridans
- Streptococcus gallolyticus
- HACEK group bacteria
- Staphylococcus aureus
- Enterococcus sp