Meningitis

Epidemiology. 1

Aetiology. 1

Bacterial meningitis. 1

Streptococcus pneumoniae. 1

N. meningitides. 1

Enteric Gram negative bacilli 1

Group B strep. 2

Listeria monocytogenes. 2

Staph aureus. 2

Viral 2

Clinical Features. 2

Bacterial 2

Viral 3

Dx. 3

Lumbar Puncture. 3

Treatment 3

Empirical antibiotics. 3

Prehospital 3

Empirical hospital 3

Manage ICP. 4

Contact tracing and chemo prophylaxis. 4

Epidemiology

Bacterial Meningitis

2.5/100,000 per year

Viral Meningitis

Unknown

Up to 12 per 100000 per year

Aetiology

Bacterial meningitis

1. Streptococcus pneumoniae 50%

2. Neisseria meningitis 25% (60% in age 2-20)

3. Group B strep 15%

4. Listeria monocytogenes 10%

5. Haemophilius influenzae <10%

Streptococcus pneumoniae

Gram positive cocci that grow in chains

Risk factors

Pneumococcal pneumonia, sinusitis, otitis media

Alcoholism

DM

Splenectomy

Hypogammaglobulinaemia, complement deficiency

Head trauma with skull fracture and CSF rhinorrhoea

20% mortality

N. meningitides

Gram negative aerobic diplococci

Oropharyngeal colonization

Can be asymptomatic carrier

Can have fulminent disease with death within hours

Enteric Gram negative bacilli

Risk factors

DM

Cirrhosis

Alcoholism

Chronic UTI

Group B strep

Largely neonates but also elderly people with other medical conditions

Listeria monocytogenes

Gram positive rod

Neonates

Pregnant females

>60yrs

Immunocompromised

From food contaminated with listeria - milk, cheese, processed food

Staph aureus

Post surgical procedures

Viral

Common	Unkown Enterovirus HSV-2 VZV	?~50% ~25% ~15% ~5%
Less Common	HSV-1 Arbovirus HIV	(?Population)
Rare	Adenovirus Influenza Mumps CMV Parainfluenza Rubella EBV

Enterovirus

· Culture of stool can increase yoeld

HSV-2 Meningitis

· 7% have genital lesions present at presentation

· 18% have history of gential lesion

· ~ A third of patients have had an episode of meningitis in the past

Clinical Features

Bacterial

Acute vs. Subacute

Classical triad

• Fever >90%
• Headache >90%
• Nuchal rigidity >90%

Other:

• Alteration in mental state - lethargy, coma >75%

• Nausea
• Vomiting
• Photophobia
• Seizures
• Raised ICP

- 90% opening pressure >18cmH2O

- 20% opening pressure >40cmH2O

- Decreased consciousness

- Papilloedema

- Dilated, poorly reactive pupils

- CN VI palsy

- Cushings Reflex - bradycardia, HTN, irregular respirations

· Kernigs sign - flex hip with knee flexed then extend knee, positive if painful

· Brudzinski’s sign - passive neck flexion auses spontaneous flexion of hips and knees

Rash in meningococcaemia:

· diffuse erythematous maculopapular rash that then becomes peteichial

· Trunk, lower extremities

Viral

• Fever
• Headache (frontal, ret orbital and photophobia)
• Nuchal rigidity (often mild)

• Malaise, myalgia, anorexia, N+V, abdo pain, diarrhoea
• Lethargy and Drowsiness - Mild

NOT

• Seizures, profound changes in conciousness
• Kernigs/Brudzinski’s usually absent

Dx

• CT prior to LP if:
• Recent head trauma, immunocompromise, malignancy, focal neurological findings, papilloedema or dec LOC, age >60

• Blood cultures

Lumbar Puncture

	Bacterial	Viral	Fungal	TB
Opening pressure	>18cm H20	N or mild elevation
WCC	5-2000/ml	5-500		5-1000
Differential	>90% Neutrophils	Lymphocytes (Neut. can predominate - early)	Lymphocytes	Lmyphocytes
RCC	None
Glucose	<2.2 (in 80%)	Normal	<2.2	Low
CSF/Serum glucose	<0.4	>0.4	<0.4
Protein	>0.45g/L (in 90%)	0.2-0.8g/L		Often >1.0g/L
Gram stain	Pos in >60%	Negative		ZN stain
Culture	Pos in >80%	Often neg
PCR	Research only	Often positive
Antigen test	Pos for meningococcal in 50% of cases (correlates with G stain)

Differentiating bacterial from viral – bacterial more likely if:

· Glucose <2.2mmol/L

· Protein >1.5g/l

· WCC >500

Treatment

Empirical antibiotics

Prehospital

Benzylpenicillin IM/IV

OR

Ceftriaxone

Empirical hospital

Ceftriaxone (high dose 2g bd)

Alternative Cefotaxime (esp in infants <1yrs)

PLUS

(<3months and >15yrs) to cover Listeria Monocytogenes

Benzylpenicillin OR amoxy/imperilling

PLUS

If Gram positive diplococci or if neutophils present and no organisms seen

To cover penicillin resistant Steptococcus pneumonia

ADD Vancomycin (500mg q6h)

- To cover penicillin resistant pneumococcus

- Some centre use routinely, others only if pneumococcus suspected.

Dexamethasone

• Reduced number of ‘poor outcomes’
• Greatest benefit if pneumococcal meningitis
• Give before antibiotics
• High dose 10mg IV qid
• Should NOT be used in shocked patients

Manage ICP

- elevate head, hyperventilate, mannitol

Contact tracing and chemo prophylaxis

- For Neisseria meningiditis:

Ceftriaxone 250mg IM stat (preferred during pregnancy)

Ciprofloxacin 500mg PO stat (preferred for women on OCP)

Rifampicin 600mg PO BD for 2/7

Hib

Rifampicin 600mg PO daily for 4/7

Vaccinate contacts

Viral Meningitis

Aciclovir 500mg Q8H for 3 days?

VZV less responsive than HSV

Chronic Meningitis

· Symptoms and signs >4 weeks

Clinical features

· Headache

· Fever

· Meningism

· Altered mental state

· Focal signs – cranial nerve palsies, nerve root lesions

Aetiology

· Unknown 20%

· Non-infectious

o Neoplastic

o Sarcoidosis

o Vasculitis

o Chemical

o CT disease – SLE

o Behcet’s disease

o VKH syndrome

o Fabry’s disease

o Sweet disease

o SAH

· Infections

o Viral

1. Common – HIV

2. Rare – enterovirus, HSV etc.

o Bacteria

1. Common – TB, Syohilis, Borrelia (lyme)

2. Rare

o Ricketsial

1. Brucellosis, leptospirosis

o Fungal

1. Cryptococcus

o Parasites

1. Angiostrongylus, Cysticercosis

Diagnosis

· Many organisms take many weeks to grow in culture

· >10% eosinophils – parasites or lymphoma

· Low glucose – TB, Fungi, Metastases, sarcoidosis (maybe)

· Neutrophils mainly – Fungi, Drug-induced, Early TB, Nocardia, actinomyces, Brucella

· Meningeal biopsy

o 20-30% yield (up to 80% if enhancing meningeal lesion on MRI is biopsied)

· Cytology

o May pick up 50% of neoplastic meningitis

o

TB Meningitis (Sensitivity of tests)

· AFB 5-25%

· PCR 50-70%

Idiopathic Hypertrophic Pacymeningitis.