Neisseria and Haemophilus

Question 1

What is the only genus of gram negative cocci that frequently causes disease?

Answer 1

Neisseria

Question 2

Is neisseria motile or non-motile

Answer 2

Non-motiile

Question 3

Describe the oxygen requirements of Neisseria

Answer 3

Neisseria is an aerobe

Question 4

Is Neisseria an obligate or opportunistic human pathogen?

Answer 4

Obligate

Question 5

Describe the difference in the virulence of N. meningococcus and N. gonococcus

Answer 5

• N. Meningococcus has a large capsule

- N. gonococcus has no capsule but strong adhesins and phase/antigenic variation

Question 6

What are the 4 major reasons that N. gonoccoi is so infectious?

Answer 6

1. Shed in genital secretions (although not motile)
2. Can enter epithelial cells
3. Extracellular protesase cleave IgA1
4. Uses host-derived antigens as camoflage

Question 7

Is Haemophilus gram positive or negative? What is its shape?

Answer 7

Small Gram-Negative coccobacilli

Question 8

What is the oxygen requirement for Haemophilus?

Answer 8

Aerobic

Question 9

Where in the human body does Heamophilus reside?

Answer 9

Colonizes the upper respiratory tract of almost everyone

Question 10

What 2 things does H. Influenzae need for growth?

Answer 10

1. NAD+ and hemin (X factor) which requires lysed blood (chocolate agar)
2. Need capsule to be virulent

Question 11

What are the 4 Virulence Factors for Haemophilus?

Answer 11

1. Polyribosyl ribitol phosphate capsule
2. Endotoxin (causes pathogen-directed endocytosis)
3. IgA1 protesase (just like Neisseria gon.)
4. Pili and OM proteins (like N. gonoccocus)

Question 12

How can you prevent an infection by Neisseria?

Answer 12

1. Behavioral (condoms, early diagnosis/treatment)
2. Vaccines (difficult to make tho)
   a) Quadrivalent (MPSV4) derived against capsular polysaccharide from 4 serotypes
   b) Tetravalent (MCV4) which is a polysaccharide-protein conjugate (children t respond well)

Question 13

How do Psedumonas adhere?

Answer 13

Mediated by flagella and pili
-interactions with glycolipid (cleaves sialic acid to create asialo GM1; receptor for type 4 pili) on host cells and also TLR5
….basically they cleave a glycolipid to create their own receptor for a pili

Question 14

Why are people with cystic fibrosis the most likely to get infected by P. aeruginosa?

Answer 14

1. They have decreased sialylation of surface glycolipids (bacteria binds to these asialo-glycolipids)
2. Dehydration of respiratory secretions (impairs mucocilary system)
3. Mucoid expopolysaccaride shields organism from immune system

Question 15

What is the trouble with treating P. aeruginosa?

Answer 15

In some hospitals an antibiotic resistant strain of P. aeruginosa predominates