Infections of the CNS Flashcards
(53 cards)
What is more seroius meningitis or sepsis?
Sepsis
What are the clinical features of meningitis?
- Headache, sore throat, drowsiness
- Rapid onset fever, photophobia, neck stiffness
- Level of consciousness progressively falls
- Petechial or purpuric rash
- Intravascular coagulation, endotoxaemia, shock, multi-organ fever, raised intracranial pressure
- Life-threatening emergency
What is a petechial rash?
- Red/brown/purple pinpoint spots on the skin that are a result of bleeding
- Do not lose colour when touched
- Clinical sign of meningitis
How do you check whether an individual has meningococcal meningitis?
Glass test - skin does not blanch
What is purpura fulminans?
Blood spots, bruising and discolouration of the skin resulting from coagulation in small blood vessels within the skin and rapidly leads to skin necrosis and disseminated intravascular coagulation
- Sign of acute meningitis
What are some clinical signs of meningitis in babies?
- Tense or bulging soft spot on their head
- Refusing to feed
- Irritable when picked up, with a high pitched or moaning cry
- A stiff body with jerky movements, or else floppy and lifeless
What are some clinical signs that are more specific to meningitis than septicaemia?
- Severe headache
- Stiff neck (viral)
- Dislike of bright lights (viral)
- Seizures (viral)
What is sepsis?
Whole body inflammation
How can infectious agents reach the CNS?
- Breach by infectious agents of BBB at arachnoid membrane in ventricles -> meningitis
- Breach of blood brain barrier (tight junctions) -> encephalitis
- Direct spread;
Sinuses
Otitis media
Skull fracture
What laboratory tests should be carried out if patient is suspected of meningitis?
Blood - FBC - Coagulation screen - Blood culture - PCR or NAAT - Blood glucose - UandEs CSF - White cell count - Gram stain - Ziehl-Neelsen stain (TB) - India ink (negative stain - shows whether microbe has capsule) - NAAT
What stain/test is used to find out whether a microbe has a capsule?
India ink
When would a lumbar puncture not be performed?
- GCS <9
- Intracranial pressure
What are the 4 most common bacterial causes of meningitis?
- Neisseria meningitidis
- Haemophilus influenzae
- Streptococcus pneumoniae
- Mycobacterium tuberculosis
What are the most common viral causes of meningitis?
Enteroviruses - Echovirus - Coxsackie viruses AandB Hepres simplex 1 and 2 Paramyxovirus
What is paramyxovirus a compliacation of?
Mumps
What fungi can cause meningitis?
Cryptococcus neoformans (HIV+)
What are the protozoa which cause meningitis?
Sub-saharan Africa
- Amoebea
- Naegleria
- Acanthamoeba
What are the features of neisseria meningitidis?
- Meningicoccal
- Gram negative
- Intracellular diplococus
- Only infects humans
- Exists as normal microbiota in nasopharynx
How is neisseria meningitidis spread?
Droplet spread or direct contact from carriers
What are the 5 strains of neisseria meningitidis?
A, B, C W135, Y
What are the features of Haemophilus influenzae?
- Gram negative
- Cocobacilli
What are the different serotypes of haemophilus influenzae able to cause disease?
A-F
- Most virulent strain is type B (Hib)
What are the features of streptococcus pneumoniae?
- Pneumococcal disease
- Chains of cocci
- Gram positive
- Exists as normal microbiota in nasopharynx
- Also causes pneumonia, otitis media
What are some virulence factors bacteria can have in bacterial meningitis?
- ANti-phagocytic polysaccharide capsule
- Endotoxin
- IgA protease
- Outer membrane proteins (OMPs)
- Pili (fimbriae)
All play an important role in pathogenesis
