Microbio 1: CNS infections + meningitis

Question 1

What is meningitis?

Answer 1

Inflammation of meninges

Question 2

What are causes of meningitis?

Answer 2

Bacterial: Neisseria meningitidis, Streptococcus pneumoniae

• Neonates: Group B Strep, Listeria monocytogenes, E. coli
• Elderly: Group B Strep, Listeria monocytogenes
• TB (subacute)

Viral: Enterovirus (coxsackie, echovirus), mumps, HSV2

Fungal: Cryptococcus neoformans (chronic)

Question 3

What is meningococcus and pneumococcus?

Answer 3

N. Meningitidis = meningococcus

S. Pneumoniae = pneumococcus

Question 4

What are the symptoms of meningitis?

Answer 4

Headache, photophobia, neck stiffness, fever, non-blanching rash (meningococcal septicaemia - not always needed in meningitis)

Viral: similar presentation but often less severe

Subacute / chronic: headaches for months, confusion, personality changes etc

Question 5

What is Ix of meningitis?

Answer 5

ABCDE (inc obs, bloods - vbg, cultures, fbc and crp)

CT head - if suspicion of raised ICP before

LP

Question 6

What are the LP findings in bacterial, viral and TB caused meningitis?

Answer 6

Bacterial

• Appearance = Turbid / cloudy
• Glucose = Low
• WCC = High - polymorphs
• Protein = >200
• Opening pressure = Raised

Viral

• Appearance = Clear
• Glucose = Normal
• WCC = High - mononuclear (lymphs)
• Protein = <200
• Opening pressure = Normal

TB

• Appearance = Clear or Turbid
• Glucose = Low
• WCC = High - mononuclear
• Protein = >200

Question 7

Mx of meningitis?

Answer 7

Bacterial: IV ceftriaxone + corticosteroids (reduce inflammation)
(If Listeria suspected -> add ampicillin / amox - amp in neonates, amox in elderly50+)

Viral: supportive (self-limiting); often use Abx to cover bacterial

Altered consciousness / personality changes (? encephalitis): add IV aciclovir

Question 8

What is encephalitis? how to differentiate from meningitis?

Answer 8

Inflammation of brain parenchyma (the brain itself)

Often present w/ fluctuating conciousness and personality changes

Question 9

What is the most common cause of encephalitis? presentation?

Answer 9

It is usually viral -> most common cause is HSV1

Often present w/ fluctuating conciousness, confusion & personality changes

Question 10

What are the investigations for encephalitis?

Answer 10

ABCDE approach

CT head - if suspicion of raised ICP before

LP – as for viral meningitis

• Appearance = Clear
• Glucose = Normal
• WCC = High - mononuclear (lymphs)
• Protein = <200
• Opening pressure = Normal

Question 11

What is the mx of encephalitis?

Answer 11

IV aciclovir + dexamethasone

Question 12

A patient presents with headache, photophobia, neck stiffness and fever. You suspect meningitis so a lumbar puncture is performed. The CSF fluid is turbid in appearance, and analysis reveals low glucose and a high WCC (polymorphs). What is the most likely cause of the symptoms?

a) Bacterial meningitis
b) Viral meningitis
c) TB meningitis
d) Bacterial encephalitis
e) Viral encephalitis

Answer 12

a) Bacterial meningitis - pus in csf = turbid + neutrophils

Question 13

You suspect bacterial meningitis in an elderly patient. What is the most appropriate initial management?

a) ABCDE, IV cefriaxone
b) ABCDE, IV ceftriaxone + dexamethasone
c) ABCDE, IV ceftriaxone + dexamethasone + ampicillin
d) ABCDE, IV ceftriaxone + ampicillin
e) Discharge the patient

Answer 13

c) ABCDE, IV ceftriaxone + dexamethasone + ampicillin

Elderly + Neonates at increased risk of Listeria caused meningitis hence add ampicillin to cover this