Lc 15

Question 1

What are two species of pathogenic neisseria species?

Answer 1

N.gonorrhoeae and N.meningitis

Question 2

Explain the type of neisseria and its shape and function

Answer 2

Gram negative diplococci

Kidney bean shaped

Non motile,non spore forming

Question 3

In what conditions they grow?

Answer 3

-chocolate agar bc they are fastidious and require enriched medium

Primary culture of clinical specimens on selective medium (modified thayer martin agar)

Question 4

How do we Neisseria species?

Answer 4

-they are both oxidase positive
- gonococcus : glucose agar
Meningococcus: maltose and glucose
- MALDI-TOF : identifies Neisseria bacteria

Question 5

Explain neisseria species structure and antigens and how they perform immune evasion

Answer 5

Major antigens (pili, outer membrane proteins(Por,Opa), lipooligosaccharide(LOS) )

They disguise

Question 6

Explain Por’s structure and how they invade host cells

Answer 6

Por: most abundant structural surface protein.

Attach to complement receptor 3(CR3) on cervical epithelial cells in women.

Por is used for serological classification of gonococcci —> two structural classes Por A and Por B is used.

Question 7

Pili functions in initial attachment to host cells. What receptors do they bind to in host cells?

Answer 7

CD46 on male urogenital epithelial cells
CR3 in female cervical epithelium cells

Question 8

There are two variations in pili. Explain them

Answer 8

Phase variation : on/ off

Antigenic variation : different gene sequences

Question 9

What does Opa expression determine?

Answer 9

Colony phenotype: opaque—> Opa expressed
Transparent—> Opa not expressed

Question 10

How do Opa function?

Answer 10

They attach to host cells. Crucial role in establishment of infection in women

Question 11

There are two phase changes in Opa. What are they and how do they differ?

Answer 11

Opa+ : cervical isolates

Opa- : isolates obtained during menses

Question 12

What is the major role of LOS?

Answer 12

Produce inflammatory mediators.

Attach to some female host cells

Sialylated LOS resists serum and attenuates inflammatory response

Question 13

How do gonorrhea infection of male and female genitalia differ?

Answer 13

Male: acute urethritis
Female : asymptomatic

Question 14

How do pathogenesis in male genitalia work

Answer 14

-Initial attach to CD46 to male urethral epithelium
-Opa expression (pili +opa) results in closee adhesion between gonococci and host cells

Question 15

How do pathogenesis in male urethra work?

Answer 15

Gonococcus enters and multiply within epithelial cells and reach the submucosa

Hematogenous(bloodstream infection) occur

Symptomatic infection

Question 16

How do pathogenesis in female genitalia work?

Answer 16

Pili and Por bind to CR3 on cervical epithelial cells

iC3b deposits on LOS, binds to CR3

Internalization via CR3 doesn’t triggeer inflammatory response

—> asymptomatic infection

Question 17

What is the main difference structure of n.gonococcus and n.meningitis?

Answer 17

N.meningitidis have polysaccharide capsules

Question 18

What is the resrvoirs of gonococcal infections?

Answer 18

Extragenital gonorrhea

Question 19

What are the clinical spectrum and manisfestations?

Answer 19

Urethritis
Rectal
Pharyngeal
Cervicitis
Salpingitis
Disdminated infection
Conjunctivitis

Question 20

What are the incubation period and symptoms of urethritis

Answer 20

Develop symptoms in 1-6 days,

Urethral discharge and dysuria
erythema and edema

Question 21

Characteristics of urogenital infection in women

Answer 21

Asymptomatic
Symptoms range from minimal to severe
Incrased vaginal discharge
Dysuria(pain and burning)

Question 22

What are the symptoms of salpingitis?

Answer 22

Lower abdoman pain, abnormal menses, inflammation of fallopian tube,

Important cause of infertility, ectopic pregnancy

Question 23

What are some extragenital gonorrhea?

Answer 23

Rectal and pharyngeal

Both asymptomatic and difficult to treat

Question 24

How do you diagnose gonorrhea

Answer 24

GC diagnosis- nucleic acid amplification test
Gram stain of mald urethral discharge
Culture—> highly sensitive but poorly sensitive to extragenital specimens

Question 25

How do se treat gonorrhea

Answer 25

Because of antimicronial resistance

Use ceftriaxone
But there are no vaccine

Question 26

What are the antigens of neisseria meningitidis?

Answer 26

Capsular polysaccharide, Los, pili, OMPs

Question 27

What is the cause of antigenic diversity ?

Answer 27

Due to interspecies genetic exchange with closely related Neisseria species

Question 28

What groups cause most serious disease of n.meningitidis?

Answer 28

A,B,C,W,Y

Question 29

N.meningitis is asymptomatic carriage. How many people carry it and who are most commonly affected?

Answer 29

10-20% , most in adolescents and young adults.

Question 30

What are the pathogenesis of N.meningitidis?

Answer 30

Attachemeng to oropharynx by pili
Disemination to blood stream—> invasion through blood brain barrier

Question 31

How do we diagnose meningitidis?

Answer 31

PCR, gram stain of CSF, culture from blood

Question 32

How do we treat n.meningitidis?

Answer 32

Penicillin G, steroid , antiobiotic , vaccination(MenACWY, MenB)

Question 33

Why are the recently approved meningococcal vaccines effective against many meningococcal serogroups including serogroup B?

Answer 33

Because the vaccine is protein basesd