Neisseria meningitidis Flashcards
Describe the gram stain appearance on N. meningitidis.
gram negative (pink) diplococcus (always in pairs)
Is N. meningitidis part of the normal microflora?
Yes, nasopharynx commensal in many individuals. Can cause disease in e.g. immunocompromised individuals
How is N. meningitidis transmitted/reaches site of infection?
inhalation of droplets
What are the risk factors for N. meningitis infection?
- recent viral/mycoplasma upper respiratory tract infection
- smoking
- complement deficiency
Which 2 serious diseases can N. meningitidis give rise to?
- meningitis (one of most frequent causes)
- fulminant meningococcaemia (sepsis) - intravascular coagulation, circulatory collapse and potentially fatal shock
In each case, symptoms can occur with extremely rapid onset and great intensity. Can progress in hrs to death.
Describe the management of N. meningitidis infection.
- Antibiotics: ceftriaxone - can penetrate CSF
- Supportive: O2 support, fluid challenge
What type of antibiotic is ceftriaxone?
cephalosporin (penicillin/B-lactam)
How is N. meningitidis infection diagnosed?
- Samples from CSF or blood cultured on chocolate agar - gram stain
- latex agglutination tests with serogroup-specific anticapsular antibody can be used to obtain rapid presumptive identification of serogroup-specific meningococci in CSF
How can N. meningitidis infection be prevented?
- vaccination: MenC conjugate, MenACWY, MenB
2. prophylactic antibiotics
What are the N. meningitidis serogroups? Which is most prevalent in the UK?
groups based on polysaccharide capsular antigen - at least 13 serogroups
serogroup B
Name 3 N. meningitidis virulence factors.
- Pili - enhances attachment (e.g. to nasopharyngeal mucosa)
- Polysaccharised capsule - antiphagocytic and antigenically diverse
- Lipopolysaccharide endotoxin - stimulates inflammation
Describe symptoms of meningococcal meningitis.
- non-blanching purpuric rash
- fever
- headache
- stiff neck
- photophobia.
- confusion, unconsciousness, seizures
- Shock: tachycardia and/or hypotension, respiratory distress, altered mental state and poor urine output.
- Kernig’s sign (pain and resistance on passive knee extension with hips fully flexed).
- Brudzinski’s sign (hips flex on bending the head forward).