Encapsulated Bacterial Pathogens

Question 1

Haemophilus influenzae grows on _______________.

Answer 1

chocolate agar with factors V and X

Think of the Sketchy chocolate shop with the 5 cent candies and the 10 cent chocolates.

Question 2

H. influenzae grows near ______________, called satellite colonies.

Answer 2

S. aureus colonies (from which they get their NAD)

Question 3

Virulent strains of Streptococcus have _____________.

Answer 3

capsules

Question 4

Which strain of N. meningitidis is most often associated with epidemics?

Answer 4

Type A

Question 5

Why can’t there be a vaccine to type B N. meningitidis?

Answer 5

The main component of its outer membrane is N-acetylneuraminic acid which is also found in human tissues.

Question 6

How does N. meningitidis get to the brain?

Answer 6

Hematogenously

Question 7

Most of the deaths from the 1918-1919 flu were from _______________.

Answer 7

secondary bacterial infection

Question 8

Why aren’t anti-capsular vaccines given to children?

Answer 8

Children develop a poor humoral response to capsule.

Question 9

There are no vaccines against the _____________ strain of N. meningitidis.

Answer 9

B (although recently a vaccine has been developed and is being evaluated for efficacy)

Question 10

Acapsular forms of capsulated bacteria can cause ________________.

Answer 10

localized disease (e.g., sinusitis, OM)

Question 11

Although there are ~90 serotypes of S. pneumoniae, only _________ strains cause 90% of the disease.

Answer 11

12

Question 12

The N. meningitidis capsule in strain B is identical to what other bacterial capsule?

Answer 12

E. coli K antigen

Question 13

All three of the encapsulated organisms in this lecture produce what virulence factor?

Answer 13

IgA protease

Question 14

The 23-valent pneumococcal vaccine has been shown to be effective at preventing bacteremia, but _______________.

Answer 14

pneumococcal bacteremia is uncommon; this has prompted many people to question the value of this vaccine