Meningitis

Question 1

What is meningitis?

Answer 1

infection of the meninges which leads to inflammation of them

Question 2

What is encephalitis?

Answer 2

inflammation of the CNS tissues

Question 3

What is cerebritis?

Answer 3

inflammation of the cerebellum

Question 4

what is myelitis?

Answer 4

inflammation of the spinal nerve

Question 5

what are some common causes of CNS infections?

Answer 5

viral - meningo-encephalitis

fungal - meningitis

parasitic - cerebral malaria

bacterial - meningitis

Question 6

what is an example of a virus which can cause CNS infection?

Answer 6

Herpes simplex virus 1
- live in peripheral nerves and can travel back into the CNS

poliovirus

Question 7

What is an example of a fungi that can cause CNS infections.

Answer 7

Candida

Aspergillus

Question 8

What are some clinical features of CNS infection?

Answer 8

Focal neurology
Papilloedema (inflammation of the optic nerve)
Impairment of consciousness
Seizures
Fever
Headache

Question 9

What are some signs of meningitis?

Answer 9

Neck stiffness (due to inflammation of nerve roots in cervical spinal cord)

Photophobia

Kernigs sign

Question 10

What are three ways that organisms can reach the CNS?

Answer 10

Direct access to CNS via broken barriers

Bacteraemia/viraemia/parasitaemia (spread to CNS via the blood).

Neuronal spread (virus especially) from peripheral nerves to the CNS

Question 11

What is bacteraemia?

Answer 11

Spread of focal infection to distant organs.
Spread by the blood.

Can cause meningitis, endocarditis, osteomyletis etc.

Question 12

What is septicemia?

Answer 12

bacteraemia + sepsis bacteria produce endotoxins which initiate an immune response.

Question 13

What are some symptoms of sepsis?

Answer 13

Raised heart rate

Low BP

High heart & breathing rate (tachycardia, tachypnoea)

Fever

Question 14

How can we diagnose CNS infections clinically?

Answer 14

Signs of CNS dysfunction

Signs of meningeal inflammation

Fever

Question 15

How can we diagnose CNS infections in the lab?

Answer 15

CSF sampling (lumbar puncture)

Radiology (CT skin to see inflammation)

Biopsy

Question 16

What is a lumbar puncture and what is its use?

Answer 16

Aims to take CSF from the subarachnoid space in the lumbar spinal cord btw vertebrae L3/L4.

We can then analyse changes in the cell count, protein count and glucose count of the CSF to help us make a diagnosis.

Question 17

What changes in CSF would you expect to see in bacterial meningitis?

Answer 17

increased cell count 2000-20000

Polymorphs (neutrophils)

increased protein count >100mg/ml

Decreased glucose (bacterial metabolism)

Question 18

What changes in CSF would you expect to see in viral meningitis?

Answer 18

Mononuclear cells

lesser cells but still increased 100-1000 cells

50-100 mg/ml proteins

no change in glucose

Question 19

Name three bacteria which can cause bacterial meningitis?

Answer 19

1. Neisseria meningitidis
2. Streptococcus pneumoniae (pneumococcus)
3. H. influenzae (however lots of vaccines against this)

Question 20

What is the 3 most common bacteria which cause bacterial meningitis in neonates (<1 month old)

Answer 20

group B streptococcus

E.coli

Listeria monocytogenes.

Question 21

What are the 3 most common causes of bacterial meningitis in older people?

Answer 21

Streptococcus pneumoniae

E.coli

listeria monocytogenes

Question 22

What are the methods of molecular diagnosis of bacterial meningitis?

Answer 22

PCR

Multi locus sequence typing

Detection of resistance genes.

Question 23

What are the disadvantages of plain polysaccharide vaccines?

Answer 23

poor immune response in children <2 years (neonates and infants still susceptible)

short lived immunity

no memory

no effect on nasopharyngeal carrage.