Neisseria Infections

Question 1

What are the two species of pathogenic Neisseria?

Answer 1

N. gonorrhoeae, N. meningitidis

Question 2

Describe pathogenic neisseria

Answer 2

Gram-, pyogenic diplococci, oxidase and catalase positive, fastidious (requires CO2 for growth), Facultative intracellular pathoges

Question 3

Compare the clinical presentations between Neisseria gonorrhoeae and C. Trachomatis

Answer 3

They present identically with respect to sex.

Question 4

What are the N. gonorrhoeae virulence factors?

Answer 4

1. Pili
2. OM proteins: P1, P2, P3
3. Iron-binding proteins
4. LOS
5. IgA proteases

Question 5

What role does N. gonorrhoeae pili play?

Answer 5

Primary adhesin, twitching motility, phase and antigenic variation

Question 6

What role does the Outer membrane proteins play in N. gonorrhoeae?

Answer 6

P1: impedes phagolysosomal fusion and oxidative burst; resistiant to C’
P2: Phase and antigenic variation
P3: Blocks antibodies

Question 7

What role does iron binding proteins play in N. gonorrhoeae ?

Answer 7

Tbp: binds transferrin, Lbp: binds lactoferrin, Hpu binds hemoglobin and haptoglobin

Question 8

What role does LOS play in N. gonorrhoeae infection?

Answer 8

Endotoxin; antigenic variation

Question 9

What is the resevoir of N. gonorrhoeae?

Answer 9

Human mucosal epithelial surfaces; asymptomatic individuals. Transmitted by direct contact of mucosal surfaces.

Question 10

Describe N. gonorrhoeae attachment.

Answer 10

Pili, LOS, porins; Usually to non-ciliated mucsoal epithelial cells. Sloughing of epithelial cells triggers acute inflammatory response. Can survive in PMNs

Question 11

How is N. gonorrhoeae diagnosed?

Answer 11

Gram stain of purulent exudate; Culture.

Question 12

What two diseases do N. meningitidis cause?

Answer 12

Meningitis, septicemia; Can cause fulminating disease (Waterhouse-Friderichsen syndrome)

Question 13

What is the resevoir of N. meningitidis?

Answer 13

Human upper respiratory tract; Exclusively a human pathogen. Transmission by aerosols. Colonization of nasopharynx similar to GC.

Question 14

Describe bacterial multiplication of N. meningitidis.

Answer 14

1. In carriers, it remains in nasopharynx, enters submucosa and bloodstream; Causing meningococcemia.
2. Can cross Blood-brain barrier(BBB) into the CNS to replicate in the meninges; Meningitis

Question 15

What does N. meningitidis do once it crosses the BBB?

Answer 15

It multiplies and sheds LPS, and PG which triggers a massive inflammatory response in the sub-arachnoid space.

Question 16

Describe the virulence factors of N. meningitidis.

Answer 16

Same as N. gonorrhoeae except for Capsule.

Question 17

What are the effects of LOS?

Answer 17

Damage to epithelium, triggers inflammatory response; Fever, thrombocytopenia, skin rash and disseminated intravascular coagulation (DIC)

Question 18

What population is most susceptible to N. meningitidis?

Answer 18

Children and young adults; Particularly those with C’ deficiencies( C5,6,7,8). Treat with antibiotics; Cephalosporins

Question 19

Compare N. gonorrhoeae to N. meningitidis.

Answer 19

N. gonorrhoeae: Always pathogenic but may not cause symptoms, Sexual transmission, rarely fatal; No protective immunity.
N. meningitidis: Usually commensal, airborne transmission, life threatening; vaccine available.