Neisseria Flashcards
How to classify?
Gram negative intracellular diplococci
What are the virulence factors?
for both N.meningitidis and N.gonorrhoeae
- Lipo-oligosaccharide (inflammation) in outer cell membrane (same as LPS endotoxin)
- Outer membrane components (adhesion and antigenic variation) - Fimbriae/pili and Opa (surface proteins involved in binding)
What is the virulence factor?
for N.meningitidis
Capsule
(A, B, C, Y, W135)
What do conjugated vaccines for N.meningitidis contain?
Antigen from capsules A, C, Y, W135
-Polysaccharide (not so effective in infants)/Conjugated - polysaccharide + protein
Group B vaccine does not use capsular antigen but combination of other surface antigens - proteins
Who is the vaccine given to?
Splenectomy, haematological diseases, certain travellers (Hajj pilgrims, Meningitis belt), prophylaxis of close contacts (children, household members, selected healthcare workers) in local outbreaks
What is meningococcal disease?
- Meningococcaemia (Fulminant sepsis)
- Meningitis
- Both
Pneumonia,Urethritis,Pericarditis,Endocarditis,Conjunctivitis,Arthritis
Where does N.meningitidis colonise?
Nasopharyngeal carriage (10%)
How is N.meningitidis transmitted?
Respiratory droplets
What are the outbreaks of infection of N.meningitidis?
- Institutions
- Groups of people in close contact, students, Hajj pilgrims
- Meningitis belt across Africa
Meningococcal disease has highest incidence in?
Young children
What can invasive meningococcal disease cause/present?
Initial macular rash but progress to haemorrhagic rash (petechia - purpura - ecchymoses)
What is the syndrome that N.meningitidis cause?
Waterhouse-Friderichsen syndrome
Haemorrhage into adrenal glands - haemorrhagic adrenalitis
How to diagnose meningococcal disease?
ALWAYS blood cultures
As indicated: CSF, throat swabs, other sites/joint fluid
Molecular diagnosis important as urgent antibiotics may render cultures negative
What is the treatment for meningococcal disease?
- Ceftriaxone: preferred, clear nasopharyngeal carriage
- Benzylpenicillin: narrow spectrum but multi-day dosing, resistance <1%, does not clear nasopharyngeal tissue
- Surgery for devitalised tissue
What kind of infection is N.gonorrhoeae?
Sexually transmitted infection