Neisseria Flashcards
What are two most clinically important species of Neisseria?
N. meningitidis
N. gonorrhoeae
What is the morphology of Neisseria?
Gram negative diplococci
Which species of Neisseria have a polysaccharide capsule?
N. meningitidis
On what medium can you grow Neisseria?
Thayer-Martin agar
What are the two major clinical diseases caused by N. meningitidis?
Meningitis
Meningococcemia
What is the clinical presentation of meningococcemia?
Bacteremia/sepsis
Rash with petechial lesions on body
- can get gangrenous, lead to amputation
Can progress to shock rapidly (DIC, hypotension, hemorrhage, organ failure)
What particular immune deficiency is a risk factor for meningococcal disease due to N. meningitidis?
Complement deficiency
- Or having too much Complement Factor H
What cell does N. meningitidis bind to?
Non-ciliated epithelial cells in nasal pharynx
What is the pathogenesis of N. meningitidis?
Binds non-ciliated epithelial cells in nasal pharynx
Passes through cells, disseminates via blood stream
Crosses BBB to initiate meningitis via inflammatory response
What are the virulence factors of N. meningitidis?
- Polysaccharide capsule
- Type IV pili
- LOS endotoxin
- Complement factor H binding protein
What other organism expresses a Type IV bundle forming pillus?
EPEC
How does complement factor H binding protein act as a virulence factor?
N. meningitidis can bind complement Factor H
Factor H prevents complement from attacking
What is treatment of choice for meningitis due to N. meningitidis?
Ceftriaxone
Rifampin for prophylaxis for contacts
Why is there no vaccine to serogroup B of N. meningitidis?
Because group B has polysialic acid
Since humans have sialic acid on our own cells, can’t target that
What is the morphology of Kingella?
Gram neg aerobic coccobacilli
What is the clinical presentation of Kingella?
Infectious arthritis of children
What is the treatment for Kingella?
Ampicillin or ceftriaxone
What is a common complication of N. gonorrhoeae infection in women?
Pelvic inflammatory disease (ascending infection from cervix)
What is the pathogenesis of N. gonorrhoeae?
Similar to meningitidis, but less virulent (no polysaccharide capsule)
Attaches to genitourinary epithelium via pili
Crosses epithelium but dissemination rare
Can survive within neutrophils!
What are major virulence factors of N. gonorrhoeae?
Pili (adherence) Por (porin) Opa (adherence factor, suppresses lymphocytes) LOS Fe-binding proteins
Why does N. gonorrhoeae need mechanisms of protection from immune response?
Needs to survive long enough until next sexual encounter and transmission to next partner
What are mechanisms of protection from immune response for N. gonorrhoeae?
- Antigenic and phase variation (variable antigenic targets of immune response and can switch expression on or off; makes it difficult to generate antibodies against)
- LOS sialylation (protects against bactericidal antigens)
What is the treatment of choice for N. gonorrhoeae infection?
Cefixime or ceftriaxone (both 3rd gen cephalosporins)
Often give doxycycline also (to treat Chlamydia co-infection)
Why is antibiotic resistance becoming such a big problem for Neisseria infections?
Mtr efflux pump pumps out antibiotics
