Meningitis + Intacranial infections

Question 1

Meningitis is life-threatening inflammation of the meninges due to infection by bacteria, viruses or fungi.

What organisms cause bacterial meningitis?

Answer 1

• Haemophilus influenzae B
• Streptococcus pneumoniae
• Neiseeria meningitidis
• Listeria monocytogenes (immunosuppressed, alcoholics + DM)
• E. Coli + Strep agalactiae (neonates)
• < 3months is usually strep B

Bacteria reach CNS + multiply quickly in subarachnoidal space + enhance influx of leukocytes into CSF, leads to cerebral oedema + inc ICP

Question 2

What are risk factors for bacterial meningitis?

Answer 2

• ≤5 or ≥65 years of age
• crowding
• exposure to pathogens
• non-immunised infants
• immunodeficiency
• leukaemia + lymphoma
• sickle cell disease
• cranial anatomical defects
• cochlear implants

Question 3

What ae the clinical features of a patient presenting with acute bacterial meningitis?

Answer 3

• headache, neck stiffness, photophobia
• fever
• confusion + altered mental status
• vomiting
• seizures
• infants → hypothermia, irritability, lethargy, poor feeding, apnoea
• Kernig’s sign (pain + resistance on passive knee extension w/ flexed hip)
• reduced GCS / coma
• neurological → seizures, focal CNS signs
• petechial or purpuric rash

Question 4

Septicaemia caused by Neisseria meningitidis is called meningococcal septicaemia. When someone has meningococcal septicemia, the bacteria enter the bloodstream and multiply, damaging the walls of the blood vessels. This causes bleeding into the skin and organs.

What will someone with meningococcal septicaemia look like?

Answer 4

• features of meningitis described earlier
• rash:
  
  • non blanching
  • purpuric (>2mm) or petechial (<2mm)
  • red or purple
• muscle ache / joint pains (myalgia)
• pale/mottled skin
• leg pain
• difficult to rouse
• rapid breathing
• cold extremities

Question 5

What should be done for suspected meningitis even before investigations are performed?

Answer 5

• give parenteral antibiotics
  
  • IM/IV benzylpenicillin / cefotaxime / ceftriaxone
• at earliest opporunity
• either in primary or secondary care
• do not delay urgent transfer to hospital
• only withhold benpen in those w/ clear hx of anaphylaxis after previous dose; a history of rash following penicillin is not a contraindication

Question 6

What are the emergency investigations for acute bacterial meningitis?

Answer 6

• Bloods → FBC, hyponatraemia, coag, CRP, glucose, Ca, Mg, lactate
• Cultures → (CSF), blood, throat, rectal
• Lumbar Puncture → CSF analysis: protein, glucose, gram stain, culture + antigen detection
  
  • gram +ve diplococci → pneumococcus
  • gram -ve diplococci → meningococcus
  • CIs: sepsis, haem instability, coagulopathy, seizures
• CT head → indicated prior to LP if raised ICP, reduced GCS, focal neuro deficit or seizures
• whole blood PCR

Question 7

After investigations confirm meningitis what is the remaining management?

Answer 7

• adjunctive dexamethasone → given before or within 4hrs of first dose of abx + continued for 4 days
• refer to local guidelines to guide antibiotic choice depending on organisms identified
  
  • H. Influenzae → IV ceftriaxone 10days
  • S. Pneumoniae → IV ceftriaxone 14days
  • meningococcal → IV ceftriaxone 7days
• IV fluids + supportive therapy
• notify public health england
• treat close contacts/high-risk contacts w/ oral ciprofloxacin or rifampicin - risk is highest in first 7 days but persists for 4 weeks
• hearing tests for children

Question 8

In the UK, what is the vaccination programme for meningitis?

Answer 8

• Men B → @8wks, @16wks + booster @1y/o
• 6-in-1 (Hib) → @8wks, @12wks, @16wks
• pneumococcal → @8wks, @16wks, @1y/o
• Hib/Men C → @1y/o
• MMR → @1y/o, @3y/o + @4y/o
• Men ACWY → freshers + young teens

Question 9

What are the complications of meningitis?

Answer 9

• shock, elevated ICP, hydrocephalus
• cognitive, academic + behavioural problems (longterm)
• seizures
• subdural effusion
• hearing loss

Question 10

What is the prognosis for meningitis?

Answer 10

• 15% of children develop sensorineural hearing loss, motor problems, seizures + mental retardation
• 20-30% children have cognitive, academic or behavioural problems
• up to 33% of adults have cognitive impairment
• 25% mortality in adults
• fatality rates high among pts at age extremes
• meningococcal sepsis higher mortality (40% compared to 5%)
• mortality higher in adolescents than in younger children

Question 11

What is encephalitis and what oragnisms is it commonly caused by?

Answer 11

• inflammation of the brain parenchyma
• due to their close anatomical proximity, meningitis + encephalitis often occur simultaneously
• consider encephalitis if there is altered consciousness or behaviour, confusion or seizures
• most common infectious causes are:
  
  • herpes simplex virus 1 + 2
  • enteroviruses
  • varicella

Question 12

What are the relevant investigations for encephalitis?

Answer 12

• herpes simplex encephalitis may be diagnosed based on serum + CSF viral PCR
• MRI → inflammatory changes to temporal lobes
• EEG → non-specific slow-wave changes and/or periodic complexes

Question 13

What is the treatment for (herpes-simplex) encephalitis?

Answer 13

• IV aciclovir
• should be started immediately as herpes simplex encephalitis carries significant morbidity + mortality

Question 14

How might HIV present neurologically?

Answer 14

• meningitis → consider esp w/ fungal or TB meningitis, fungal often presents in chronic or subacute way
• intra-cranial mass lesions → toxoplasmosis
• dementia
• encephalomyelitis
• cord problems
• peripheral nerve problems → eg mononeuritis complex + guillian-barre