T9-L4: Vascular Infections

Question 1

What is the clinical presentation of infective endocarditis?

Answer 1

• Non-specific illness e.g. lethargy, malaise, night sweats, anorexia, weight loss
• Heart failure - signs include SOB, orthopnea, paroxysmal nocturnal dysponea
• Results of extra-cardiac foci infection e.g. splenic infarct causing abdominal pain, stroke, back pain from

Other features include (less common):

• Janeway Lesions
• Osler’s nodes
• Splinter haemorrhages
• Roth spots

Question 2

How is infective endocarditis diagnosed?

Answer 2

3 sets of blood cultures taken at different times to confirm that there is constant bacteraemia. They should be taken from appropriate skin disinfection and to spread them out. If very acutely ill, get 2 sets within the hour.

Usual causes include staphylococci (inc. coagulase negative and S. aureus) and Streptococci and enterococci.

A low index of suspicion is required.

ECHO is also used to see the vegetations.

Question 3

How is Intravascular Catheter-Related Bloodstream Infection (CRSBI) diagnosed?

Answer 3

• Clinical diagnosis is unreliable
  
  • CRBSI should be considered in any patient with intravascular catheter and systemic signs of infection and bacteraemia or fungaemia
  • Remove the catheter and see if symptoms resolve
  • A key Test is the Differential Time to Positivity: Same organism from at least 1 peripheral blood culture and a removed catheter tip should be detected. A difference time for positivity of 2 hours is diagnostic.

Question 4

What is the pathogenesis of Mycotic aneurysm? Give 3 mechanisms.

Answer 4

1. Haematogenous seeding - seeding of the vessel wall via the blood stream e..g secondary to infective endocarditis
2. Trauma to the arterial wall learning to direct contamination e.g. in IVDU
3. Extension from contiguous infected focus e.g. secondary to septic micro emboli

Question 5

What is the aetiology of mycotic aneurysm?

Answer 5

Salmonella spp. Stap. Aureus, Strep spp. , Pseudomonas aeruginosa, E.coli

Question 6

What is the pathogenesis infected deep vein thrombosis?

Answer 6

DVTs can be seeded with bacteria during bacteraemia or inoculated directly e.g. PWID injecting into femoral vein seeds femoral DVT, infected PICC seeds axillary vein DVT

Question 7

How is infected deep vein thrombosis diagnosed?

Answer 7

Multiple (3) blood cultures, confirmation of DVT plus exclusion of other causes e.g. IE