Cardiac Infections Flashcards
What is the likely focus of a streptococcus pneumoniae infection?
Pneumonia
Menigitis
What is the likely focus of a E.coli/Klebsiella/coliform infection?
Urinary tract
Gut
What is the likely focus of a Staphylococcus aureus infection?
Skin, wound infection
Bone/joint infection
Endocarditis
Causes of Staphylococcus epidermidis in blood cultures?
Commonly a skin contaminant
Can infect prosthetic material (e.g intravascular line, prosthetic heart valve/joints)
What is infective endocarditis?
Infection of the endothelium of the heart valves
Predisposing factors for infective endocarditis?
Heart valve abnormality =
Calcification/scelrosis int he elderly
Congenital heart disease
Post rheumatic fever
Prosthetic heart valve
IV drug use
Intravascular lines
Pathogenesis of Endocarditis
Heart valve damaged
Turbulent blood flow over roughened endothelium
Platelets/fibrin deposited
Bacteraemia (e.g. dental treatment)
Organisms settle in fibrin/platelet thrombi becoming a microbial vegetation
These are friable and break off, lodging in the next capillary bed they encounter causing abscesses or haemorrhage
Which side of the heart is usually affected by endocarditis?
Left side
Mitral and Aortic Valves
What are the four most common organisms to cause endocarditis on a native valve?
Staphylococcus aureus
Viridans streptococci
Enterococcus sp
Staphylococcus epidermidis
Which “atypical” organisms can cause endocarditis?
Bartonella Coxiella burnetti (Q fever, sheep) Chlamydia Legionella Mycoplasma Brucella
What is the typical presentation of acute endocarditis?
Overwhelming sepsis and cardiac failure
Symptoms of subacute endocarditis?
Fever Malaise Weight loss Tiredness Breathlessness
Signs of subacute endocarditis?
Fever New or changing heart murmur Finger clubbing Splinter haemorrhages Splenomegaly Roth spots, Janeway lesions, Osler nodes Microscopic haematuria
How many blood cultures should be taken?
Three sets
Before receiving antibiotics
What imaging can be used for diagnosis of endocarditis?
Echocardiogram
Transoesophageal is more sensitive than transthoracic
What is early prosthetic valve endocarditis and which organisms are usually responsible?
Within 60 days
Usually infected at time of valve insertion
Staphylococcus epidermidis or Staphylococcus aureus
What is late prosthetic valve endocarditis and which organisms can be responsible?
Occurs up to many years after valve insertion due to coincidental bacteraemia
Wide range of possible organisms
Which side of the heart is usually affected by endocarditis in IV drug users?
Right side (tricuspid valve)
Which organism usually causes endocarditis in IV drug users and how doe sit commonly present?
Staphylococcus aureus, often presenting as Staph aureus “pneumonia”
What is the treatment for native valve endocarditis?
Amoxicillin and gentamicin IV
What is the treatment for prosthetic valve endocarditis?
Vancomycin and gentamicin IV + Rifampicin PO
Valve replacement usually required
What is the treatment for endocarditis in IV drug users?
Flucloxacillin IV
What is the treatment for Staphylococcus aureus (non MRSA) endocarditis?
Flucloxacillin IV
What is the treatment for MRSA endocarditis?
Vancomycin IV + Rifampicin PO
