🎯 Pathology

• inflammation of the meninges, the connective tissue layers that protect the brain and the spinal cord

• it is a life-threatening emergency

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💡 Causes

• otitis media

• sinusitis

• CSF leak

• maternal group B streptococcal infection during delivery

• sepsis

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🧫 Causative agents

• the most common causative agents are viruses; of these, echovirus and coxsackievirus are the most common

• viral meningitis is less acute and usually self-limiting

 

Most common causative agents of bacterial meningitis

• < 1 month

  • Group B streptococcus

  • E. coli

  • Listeria monocytogenes

• 1 month - 2 years

  • Streptococcus pneumonia

  • Neisseria meningitidis

  • Group B streptococcus

  • Hemophilus influenzae b (immunization reduced its incidence)

• 2 - 50 years

  • Streptococcus pneumonia

  • Neisseria meningitidis

• 50 years

  • Streptococcus pneumonia

  • E. coli

  • L. monocytogenes

  • H. influenzae b

  • Neisseria meningitidis

  • Group B streptococcus

 

Note: tuberculous meningitis (caused by Mycobacterium tuberculosis) is a rare form meningitis that can affect patients with a compromised immune system (such as due to HIV)

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🩺 Clinical features

• the classic triad of meningitis is: fever, headache, and neck stiffness.

• Other features include:

  • Photophobia

  • Confusion and altered mental status

  • Nausea and vomiting

  • Seizures

  • Cranial nerve palsies

• Special features in case of N. meningitides bacterial meningitis:

  • Petechiae or purpura, especially in pediatric patients

  • Waterhouse-Friderichsen syndrome

• Signs on physical examination include:

  • neck stiffness

  • Kernig sign: resistance or inability to allow full extension of the knee when the hip is 90 degrees flexed

  • Brudzinski sign: spontaneous flexion of the hips upon neck flexion

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🕵️‍♂️ Investigations

• full neurological examination

• bloods

  • FBC, U&E, LFTs, CRP, ESR

  • blood cultures

• lumbar puncture (best test) for CSF analysis

  • CSF analysis is essential for establishing the diagnosis and guiding the treatment

• neuroimaging (CT/MRI) are not routinely indicated

  • indicated if there are focal neurological deficits or raised intracranial pressure

 

 

 

 

 

 

 

 

💆‍♂️ Management

 

Fundamentals

• A to E approach

  • stabilise the patient and apply appropriate isolation

• empirical antibiotics ASAP (if neuroimaging is indicated, do not delay antibiotic therapy!)

  • if presenting in the community, commence intramuscular benzylpenicillin

• corticosteroids indicated for S. pneumoniae or H. influenzae meningitis

  • contraindicated in children < 3 months of age and in the case of meningococcal septicaemia

• once the pathogen is identified, tailor the antimicrobial therapy accordingly

• most cases of viral meningitis can be treated supportively

  • specific antivirals are administered if viral encephalitis is also suspected

• close contacts of meningitis should receive antibiotic prophylaxis with ciprofloxacin

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Empirical antibiotic treatment for bacterial meningitis by age group 

• < 3 months

  • IV amoxicillin or ampicillin + IV cefotaxime

    • amoxicillin and ampicillin are added for listeria cover

• 3 months

  • IV ceftriaxone or cefotaxime

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😰 Complications

• most common

  • sensorineural hearing loss

• others complications

  • Seizures

  • Elevated intracranial pressure

  • Cognitive impairment

  • Focal neurological impairment

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🧲 High-yield tips​

• if the patient is presenting in the community:

  • immediately commence intravenous or intramuscular benzylpenicillin

  • urgent transfer to hospital

• close contacts are offered antibiotic prophylaxis with ciprofloxacin

• contraindications of a lumbar puncture

  • focal neurological deficits

  • fontanelle bulging

  • cerebral herniation

  • disseminated intravascular coagulation

  • papilloedema

  • meningococcal septicaemia