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Last reviewed: 22 Mar 2025
Last updated: 18 Jan 2024

Summary

Definition

History and exam

Key diagnostic factors

  • fever
  • vomiting/nausea
  • irritable/unsettled
  • headache
  • altered mental state
  • neck stiffness
  • photophobia
  • seizures
  • focal neurological deficit including cranial nerve involvement and abnormal pupils
  • rash
  • shock
  • raised intracranial pressure
  • back rigidity
  • bulging fontanelle
  • Kernig’s sign
  • Brudzinksi’s sign
  • apnoea
  • rapid deterioration
  • hypotension
  • cold peripheries
  • toxic/moribund state
  • paresis
  • presence of risk factors

Other diagnostic factors

  • unusual skin colour
  • lethargy
  • ill appearance
  • refusing food/drink
  • muscle ache/joint pain
  • respiratory distress or breathing difficulty
  • chills/shivering
  • diarrhoea, abdominal pain/distension
  • sore throat/coryza or other ear, nose, and throat symptoms/signs

Risk factors

  • young age
  • complement deficiency
  • use of eculizumab and ravulizumab
  • immunoglobulin deficiency
  • HIV infection
  • asplenia or hyposplenia
  • university attendance
  • close contact with invasive meningococcal infection
  • household crowding
  • travel to a hyperendemic or epidemic area
  • laboratory workers
  • tobacco smoke exposure
  • recent move into a new community
  • respiratory infection
  • visiting bars/clubs
  • kissing

Diagnostic investigations

1st investigations to order

  • blood gases (including lactate)
  • glucose
  • full blood count
  • procalcitonin (or CRP)
  • coagulation profile
  • blood cultures
  • PCR for Neisseria meningitidis
  • urea, electrolytes and creatinine, serum calcium, ionised magnesium (Mg2+), ionised phosphate (PO4-)
  • liver function tests
  • cross-match (children)
  • CFS PCR for Neisseria meningitidis and Streptococcus pneumoniae
  • PCR for Streptococcus pneumoniae (adults)
  • CSF white blood cell count and examination
  • CSF total protein concentration
  • CSF glucose concentration
  • CSF microscopy, Gram stain, culture and sensitivities
  • CSF lactate (adults)
  • throat swab for culture

Investigations to consider

  • cranial CT
  • complement deficiency (children)
  • serum HIV (adults)

Treatment algorithm

Contributors

Expert advisers

Flight Doctor

Greater Sydney Area

Helicopter Emergency Medical Service

New South Wales

Australia

Disclosures

AA declares that he has no competing interests.

BMJ Best Practice would like to gratefully acknowledge the previous expert contributor, whose work has been retained in parts of the content:

Elisabeth Adderson, MD

Associate Member

St. Jude Children's Research Hospital

Associate Professor of Pediatrics

University of Tennessee Health Sciences Center

Memphis

TN

Disclosures

EA declares that she has no competing interests.

Peer reviewers

Acute Hospital Sub Dean (Cornwall)

Honorary Clinical Senior Lecturer

Consultant Emergency Physician

The Knowledge Spa

Royal Cornwall Hospital

Truro

UK

Disclosures

RT declares that he has no competing interests.

Consultant in Infectious Diseases

Clinical Tutor in Medicine and Associate Professor and Reader in Infectious Diseases

University of Oxford

Director

Oxford Centre for Clinical Tropical Medicine and Global Health

Oxford

UK

Disclosures

BA declares that he has no competing interests.

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