Infections of the CNS Flashcards
petechial/purpuric rash
doesnt go away when pushed with glass
Complications - meningitis
May affect 20+% of survivors
Seizures Hearing difficulties Other cranial nerve problems Focal paralysis Hydrocephalus Intellectual disability Ataxia
Complications - sepsis
Limb amputations
Arthritis and join pain
Skin necrosis and scarring
Organ dysfunction: liver, kidney, adrenal glands
meningitis
inflammation of the meninges
encephalitis
inflammation of brain parenchyma
sepsis
life-threatening organ dysfunction caused by dysregulated host response to infection
Blood-brain barrier (BBB)
– Tightly packed endothelial cells line the blood vessels in the brain mechanically supported by thin basement membrane.
– Breach by infectious agents causes encephalitis.
Blood- cerebrospinal spinal fluid (CSF) barrier
– Similar barrier at arachnoid membrane and in ventricles.
– Breach by infectious agents causes meningitis.
• Direct Spread to the CNS via
- Sinuses
- Otitis media
- Skull fracture
how is the BBB breached
– Growing across & infecting cells comprising barrier
– Passive transfer in intracellular vacuoles
– Carriage across in infected white blood cells
what are the three causes of meningitis
- infection
- auto-immune
- malignancy
what are the dangers of neonatal meningitis - early onset
• Occurs <7 days • Infected by heavily colonised mother • Premature rupture of membranes • Pretermdelivery • 60%fatalityrate
what are the dangers of neonatal meningitis - late onset
• Occurs <3 months
• Lack of maternal
antibody
• Poor hygiene in nursery • 20%fatalityrate
Neisseria meningitidis
Only infect humans
Normal microbiota in nasopharynx
Transmission by droplet spread or direct contact from carriers At least 12 serotypes - different in polysaccharide antigens
5 pathogenic serogroups strains – A, B, C, W135, Y
Haemophilus influenzae
Six capsular serotypes (a-f) known to cause disease
Most virulent strain is H. influenzae type b (Hib)