Cardio- Bacteria and antibiotics

Question 1

Streptococcus viridans- morphology

Answer 1

Gram-positive cocci; alpha-hemolytic, NO capsule, Optochin resistant, bile insoluble

Question 2

Streptococcus viridans- presentation

Answer 2

• Strep mutans and sanguinis variants are associated with dental caries
• Subacute endocarditis, usually in mitral valve

Question 3

Why does Strep viridans tend to affect the mitral valve?

Answer 3

Weak virulence; can only affect previously damaged valves (mitral valve prolapse, rheumatic heart disease, etc.)

Question 4

How does Strep viridans cause endocarditis?

Answer 4

Adheres to fibrin-platelet aggregates by creating dextrans from glucose