Neisseria

Question 1

Neisseria

Answer 1

Gram - Diplococci

Question 2

Neisseria lacks….

Answer 2

LPS

Question 3

Neisseria common in

Answer 3

common oral flora and other mucous membranes

Question 4

Neisseria pathogens

Answer 4

N.gonorrhoeae and N.meningitidis

Host: only humans

Question 5

Virulence Factors of N. gonorrhoeae (1)

Answer 5

phase variation and antigenic variation of pilin genes

Gonococci at different infection sites in an infected individual often express different pilin genes
because they adhere to different cell surface receptors on distinct mucosal epithelial cells.

Question 6

Virulence Factors of N. gonorrhoeae (1)

Vaccine or No?

Answer 6

Nah

Question 7

Virulence Factors of N. gonorrhoeae (1)

Capsule or No?

Answer 7

Nah

Question 8

Pathogenesis of Gonorrhea

Answer 8

ØPilE single chromosomal copy of pilin structural gene
ØStrains contain 10-15 copies of PilE variants lacking promoter and 5􀀁-end
of gene called PilS genes
ØPilS genes recombine with PilE creating unlimited antigenic variants of PilE
ØResult is that antigenic structure of pilus protein is constantly changing

Question 9

Pathogenesis of Gonorrhea

Answer 9

Phase Variation:
on/off switch for surface protein expression

In Neisseriae: Slipped Strand Mispairing resulting from presence of multiple
identical repeated sequences at 5􀀁-end of gene. Replication errors due to strand
misalignment creates reading frame errors.
Often, premature stops, but also results in ON/OFF switch.
Multiple Opa (Colony Opacity) protein copies scattered across genome; Slipped
strand mispairing results in frequent variation in Opa protein expression or
complete absence of Opa

Question 10

Pathogenesis of Gonorrhea

Answer 10

ØE. coli and other Gm- rods simple inversion

of promoter

Question 11

Virulence Factors of N. gonorrhoeae (2)

Answer 11

Pili mediate bacterial attachment to non-ciliated epithelia

bacteria proliferate and shed into secretions;

Question 12

Virulence Factors of N. gonorrhoeae (2)

Answer 12

secreted IgA protease:

Usefulness of cleaving IgA:
Coating of bacteria with IgA
Fab fragments (does not
activate complement and
also blocks binding by other
IgG and IgM)

Question 13

Virulence Factors of N. gonorrhoeae (2)

Answer 13

􀀂Serum-resistant􀀃 virulent strains cause disseminated gonococcal infections:

Strains lack Opa proteins (colony opacity proteins = outer-membrane proteins)
Neutrophils unable to engulf bacteria lacking Opa proteins.
• Sialic acid on LOS (Lipidoligosaccharide of outer membrane) binds complement
regulatory proteins, prevents complement-based phagocytosis.

Question 14

Virulence Factors of N. gonorrhoeae (2)

Answer 14

Shedding of lots of endotoxin (LOS of these bacteria) 􀀄
Binds TLR-4 (especially on dendritic cells, macrophages,
& B cells) 􀀄 secretion of pro-inflammatory cytokines (TNFalpha,
IFN-gamma, IL-1,-12, & -18) & nitric oxide 􀀄 shock

Question 15

Gonorrheal Diseases 1’

Symptomatic or No?

Answer 15

Nah

Question 16

urethritis

Answer 16

urethritis in men, urethral pus secretion

leukocytes with many gonococci

Question 17

cervicitis

Answer 17

in women, frequently some urination

sensitivity but no other symptoms

Question 18

Opthalmia Neonatorum

Answer 18

destructive eye infection, acquired during birth
o Application of erythromycin ointment into both
eyes of newborns is mandatory in many states
and is considered standard neonatal care

Question 19

Pelvic Inflammatory Disease (PID)

Answer 19

in women
Initial infection of cervix, fallopian tubes and vaginal wall glands can lead to PID (15-30%):
o gonococci enter abdominal cavity, cause liver disease
o tissue scarring causes fallopian tube abnormalities which lead to ectopic pregnancies
and sterility

Question 20

Urethral and testicular tubule scarring

Answer 20

Urethral and testicular tubule scarring, resulting from epididymitis, leads to sterility
and increased urethral infections by other microbes

Question 21

Gonorrheal Diseases (2)

Answer 21

Disseminated Gonococcal Infection (without apparent genital infection) causes skin
lesions, suppurative arthritis of a major joint, heart valve destruction

Question 22

Little or no protective immunity (???????) is observed

after recovery from an infection with N.gonorrhoeae.

Answer 22

Little or no protective immunity (pilin variability!) is observed
after recovery from an infection with N.gonorrhoeae.

Question 23

Neisseria meningitidis

Answer 23

Capsule protects intravascular survival

Question 24

Neisseria meningitidis

Gets iron how

Answer 24

transferrin

Question 25

Neisseria meningitidis can cr…

Answer 25

cross blood brain barrier

Question 26

effect of inflammatory cytokines

release induced by endotoxin activation of macrophages.

Answer 26

Contrary to other meningitis-causing infections, small local skin hemorrhages are
observed: Localized loss of vascular integrity:

Question 27

Purpura fulminans

Answer 27

blood spots, bruising, and discoloration

of skin from coagulation in small blood vessels

Question 28

Virulence Factors of N.meningitidis

Answer 28

Large capsule leads to disseminated intravascular coagulation (DIC)
Some virulent strains have capsules with sialic acid on LOS (like
N.gonorrhea): reduces phagocytosis further
Ø IgA protease
Ø Pili
Ø Shedding of lots of Endotoxin 􀀂 shock

Question 29

Effective vaccination against

Answer 29

Effective vaccination against capsular polysaccharides
MenACWY Vaccine – CDC recommended since 2005
Protection from 4 major disease-causing strains:
A, C, W135 and Y (serotyping: 12 antigenic groups)
MenB vaccine – approved in 2014 & also recommended
B capsule poly-sialic acid; Andy Marso’s case involved
serogroup B bacteria.
European MenB vaccine was used in outbreaks at
Princeton and UC Santa Barbara in 2013-2014
q Mandatory vaccination for students living in dorms
in many states, military recruits, and jail inmates