Lecture 8

Question 1

What are Parvobacteria?

Answer 1

Parvobacteria are bacilli that are so short that they are often confused with cocci.

Question 2

What is the natural habitat of Neisseria?

Answer 2

Neisseria is part of the natural flora in the human nasopharynx and genitourinary tract.

Question 3

Give examples of Neisseria.

Answer 3

Examples of Neisseria are Neisseria meningitidis and Neisseria gonorrhoeae.

Question 4

What is the peak age for Neisseria disease occurrence?

Answer 4

Neisseria Disease occurs in infants and at a second peak at approximately 18 years.

Question 5

What are the symptoms of Neisseria disease?

Answer 5

Symptoms of Neisseria disease include acute meningitis, fever, headache, seizures, mental signs, intracranial pressure, rash, purpura, and thrombocytopenia.

Question 6

What is the initial step in meningococcal pathogenesis?

Answer 6

The initial step in meningococcal pathogenesis is colonization of the nasopharynx by the bacteria.

Question 7

How do meningococcal bacteria attach to the epithelial cells of the nasopharynx?

Answer 7

: Meningococcal bacteria attach to the epithelial cells of the nasopharynx via pili and other adhesins.

Question 8

What is the role of outer membrane proteins in meningococcal pathogenesis?

Answer 8

Outer membrane proteins facilitate the invasion of meningococcal bacteria by allowing them to adhere to and penetrate endothelial cells.

Question 9

What is the purpose of capsule of n.meningitidis?

Answer 9

The polysaccharide capsule of n.meningitidis prevents phagocytosis.

Question 10

What is the basis of classification into 13 serogroups for n.meningitidis?

Answer 10

The polysaccharide capsule is the basis of classification into 13 serogroups for n.meningitidis.

Question 11

Which serogroups of n.meningitidis cause the majority of disease?

Answer 11

The majority of disease caused by n.meningitidis is due to serogroups A, B, C, W-135, and Y.

Question 12

Is there a vaccine available for serotype B of n.meningitidis?

Answer 12

Vaccination against serotype B of n.meningitidis is difficult due to the presence of sialic acid on the serotype, similar to that found on host cells.

Question 13

What is the pathogenesis of Neisseria gonorrhoeae?

Answer 13

The pathogenesis of Neisseria gonorrhoeae involves adherence to the mucosal surface of the urogenital tract using fimbriae, invasion of the epithelial cells of the mucosa, triggering of an inflammatory response, dissemination to other parts of the body, and ingestion by macrophages and PMNs.

Question 14

Which media is used to culture N. meningitidis?

Answer 14

: N. meningitidis is usually cultured from sterile body fluid such as CSF or blood, so no other organism can overgrow.

Question 15

Which media is used to culture N. gonorrhoeae?

Answer 15

N. gonorrhoeae is usually grown on chocolate agar with antibiotics because the sample is taken from an area with a lot of normal flora.

Question 16

How does Neisseria avoid surface immune response?

Answer 16

Neisseria avoids surface immune response through antigenic variability and IgA protease.

Question 17

What is the treatment for N. meningitidis and N. gonorrhoeae infections?

Answer 17

N. meningitidis is treated with Cephalosporins which are often the first choice drug, while newer cephalosporins are used for N. gonorrhoeae as it produces beta-lactamases.

Question 18

What is the characteristic feature of Moraxella catarrhalis?

Answer 18

Moraxella catarrhalis produces DNAse, indicating the absence of carbohydrates.

Question 19

What is the primary reservoir for Haemophilus influenzae?

Answer 19

The human respiratory tract is the primary reservoir for Haemophilus influenzae, with 20-50% of people being carriers.

Question 20

Which Haemophilus species cause sexually transmitted disease?

Answer 20

H. ducreyi is the Haemophilus species that causes sexually transmitted disease in the tropics.

Question 21

What are the two types of disease h,influ causes and example?

Answer 21

H.infl causes Invasive disease: Meningitis, pneumonia, epiglottitis, bacteraemia cellulitis and Non- invasive disease-Otitis media, conjunctivitis

Question 22

What are h.influ antigenic types based on ?

Answer 22

H.infl has Six antigenic types based on polysaccharide capsular antigen (a-f)

Question 23

What is the H.influ vaccine based on and when is it given?

Answer 23

Capsule based vaccine used to immunise children against H.infl (>24mths)

Question 24

Pathogenesis of h.influ?

Answer 24

The first step in the pathogenesis of H. influenzae is adherence to the respiratory epithelium, pili and outer membrane proteins. Colonize the mucosa. The bacteria produce several factors that help them survive in this environment, including type b capsule, lipooligosaccharides, and adhesins, that facilitate invasion. The type b capsule is particularly important in invasion, as it helps protect the bacterium from phagocytosis by host immune cells. It triggers an inflammatory response. The host immune system produces cytokines and chemokines that recruit immune cells to the site of infection. Neutrophils are the primary immune cells that are recruited, and they play an important role in clearing the bacterium from the host tissue. also cause tissue damage. The release of inflammatory mediators, such as reactive oxygen species and proteases, can damage host tissue and contribute to the symptoms of infection, such as fever and inflammation.

Question 25

What strains are invasive?

Answer 25

Capsulated

Question 26

How do X and V factors infleunce Haemophilus growth?

Answer 26

H.infl needs X (haeme) and V(NAD) factors to grow.
H.parainflu needs V factors

Question 27

What drugs are h.infl susceptible to?

Answer 27

H.infl is Susceptible to ampicillin, amoxicillin, newer cephalosporins, tetracycline, aminoglycosides
and sulphonamides

Question 28

What do some h.infl produce strains against?

Answer 28

produce an enzyme which
inactivates chloramphenico

Question 29

What is h.infl treated with?

Answer 29

H.infl Usually treated with cephalosporin and then treatment may be changed to ampicillin if
tests indicate susceptibility