Streptococcus pneumoniae

Question 1

S. pneumoniae

Morphology

Answer 1

Gr+ oval cocci, pairs
(streptococcus mutans - viridans)

Question 2

S. pneumoniae

Diagnostic characterstics

Answer 2

catalase -
alpha hemolysis (blood agar)
susceptable to optochin

Question 3

S. pneumoniae

Virulence factor

Answer 3

polysaccharide capsule (K AG), >100 serotypes & all require specific capsular ABs

Question 4

S. pneumoniae

Prophylaxis

Answer 4

1. Polysaccharide vaccine - thymus-independent immune response, non memory forming, not effective in young & elderly.
2. Conjugated vaccine - thymus-dependent immune response, long lasting memory, able to conjugate several AGs at the same time –> good coverage protection against many serotypes.

Question 5

S. pneumoniae

Risk groups & disease caused

Answer 5

1. Immunocompromized: alcoholics, malnutrioned, asplenic, children, elderly, those with previous viral infections and chronic lung diseases, etc.
2. pneumonia (abrupt fever, bloody sputum & chest pain), sinusitis, meningitis and bacteremia –> endocarditis