Neisseria II Flashcards
Describe Neisseria meningitidis and what groups are msot commonly infected
- A commensal & human pathogen
- A major cause of bacterial meningitis
–S. pneumoniae and H. influenzae B have vaccines
–Vaccine development lagged behind these organisms
•Most common infections in:
–<5 years
–Teenagers
–Institutionalised people (e.g. University students!)
–People with complement deficiencies
Draw a graph showing age vs cases per year of Bacterial meningitis
Describe its Epidemiology
•Commensal in 5-15% of people
- Asymptomatic carriage
•Unclear what causes invasion in some individuals
- Smoking may breach epithelial barrier in some
- Age
- Previous flu
- Close living (University Students, Halls!)
- Highly polymorphic organism
•Increase in cases winter and spring
- Dry, cold months
•Bacteraemia ± Meningitis
Epidemiology: Which sero-groups predominate around the world?
- Different sero-groups predominate around the world
–Group A in sub-Saharan Africa
–Pilgrimage associated with high dissemination of A, C, Y, W135 at times
- UK
–Serogroup B after WW I & II
–1985 Hyperendemic B serogroup period
–1995 Hyperendemic C serogroup period
•age change towards teenagers, with a high mortality rate
State some Clinical Conditions
•Bacteraemia
–Septicaemia
–Meningococcaemia
- Meningitis
- Pneumonia
- Initially
–Fever and flu-like symptoms
–vomiting
What is Meningococcaemia?
- Life threatening ± meningiti
- Bacterial division in blood
- Fever and flu-like symptoms (may resolve)
- Haemorrhagic rash in 80% of individuals
Explain the consequences of Meningococcaemia
•Shock & Intravascular coagulation
- –Serious & linked consequences of infection
•Released LOS
- –Activates
- Complement, PRR, coagulation
- Massive pro-inflammatory response
- Increased vascular permeability
- Loss of protein, fluid and electrolytes
- Cardiac output falls, extravascular fluid accumulates (pulmonary oedema & respiratory failure)
- Progression can be rapid and very severe
Describe Meningitis
- Downstream of bacteraemia
- Purulent inflammation of meninges
–NØ infiltration of CSF (unlike viral meningitis)
•Headache, fever, seizures, stiff neck, photophobia
–Often non-specific symptoms especially in young
- Rash in 50% of meningitis patients
- Mortality
–approaching 100% without treatment
–10% with antibiotics
–Higher with severe bacteraemia
How is meningitis diagnosed?
•Gram stain of CSF
–Sensitive & specific
- Gram stain of blood less useful due to low bacterial numbers
- Culture
- Oxidase/catalase help with presumptive ID
- NAAT
–Blood and CSF
Meningitis Vaccination:
How effectiveis it?
When is it given?
•Men C vaccine
–Reduced infections in immunised people by 90%
–Cases in other groups fell 75% (HERD IMMUNITY)
–Capsular polysaccharide conjugated to protein
•T cell dependent immunogen
–Given at 1 year and 14 years
When is the tetravalent vaccine given?
•Tetravalent vaccine
–Directed against A, C, Y and W135
–Capsular polysaccharide conjugated to protein
–Recommended for sub-Saharan travel
–Essential for pilgrimage
•Given at age 14
Vaccination- serogroup B (since 2015)
- Until recently there was no vaccine for serogroup B
- 4CMenB = Bexsero Factor H binding protein
–Aims to block factor H binding molecules
•Adoption by NHS in 2016
–(given at 2 & 4 months, 1 year boost)
Describe meningitis management
- Early recognition
- Antibiotics - RAPID
–Penicillins (Beta lactamases a problem)
–Cephalosporins
- Close contacts receive prophylactic antibiotics
- Close ‘kissing’ contact can increase risk 1000x
