Bacterial meningitis

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Evidence last reviewed: 28 Apr 2026
Topic last updated: 14 Aug 2025

Summary

Definition

History and exam

Key diagnostic factors

  • headache
  • neck stiffness
  • fever
  • altered mental status
  • confusion
  • photophobia
  • vomiting
  • seizures
  • hypothermia (infants)
  • irritability (infants)
  • lethargy (infants)
  • poor feeding (infants)
  • apnea (infants)
  • focal neurologic deficit
  • abnormal eye movement
  • facial palsy
  • balance problems/hearing impairment
  • bulging fontanel in infants
Full details

Other diagnostic factors

  • high-pitched cry (infants)
  • rash
  • papilledema
  • Kernig sign
  • Brudzinski sign
Full details

Risk factors

  • age ≤5 or ≥65 years
  • crowding
  • exposure to pathogens
  • nonimmunized infants
  • immunodeficiency
  • cancer
  • asplenia/hyposplenic state
  • cranial anatomic defects
  • cochlear implants
  • contiguous infection
  • smoking
Full details

Diagnostic tests

1st tests to order

  • cerebrospinal fluid (CSF) cell count and differential
  • cerebrospinal fluid (CSF) protein
  • cerebrospinal fluid (CSF) glucose
  • cerebrospinal fluid (CSF) Gram stain
  • cerebrospinal fluid (CSF) culture
  • antigen detection in cerebrospinal fluid (CSF)
  • blood culture
  • CBC and differential
  • CRP
  • electrolytes, calcium (Ca), magnesium (Mg), glucose
  • coagulation profile (prothrombin time, INR, activated PTT, fibrinogen, fibrin degradation products)
  • CT head
  • polymerase chain reaction (PCR)
Full details

Tests to consider

  • MRI head
  • transcranial Doppler
  • serum procalcitonin
Full details

Emerging tests

  • heparin-binding protein (HBP)
  • rapid antigen cerebrospinal fluid (CSF) tests
  • metagenomic next-generation sequencing (mNGS)
Full details

Treatment algorithm

INITIAL

≤1 month of age and immunocompetent

>1 month and <50 years of age and immunocompetent

≥50 years of age or immunocompromised

ACUTE

confirmed infection: Streptococcus pneumoniae

confirmed infection: Haemophilus influenzae

confirmed infection: Streptococcus agalactiae (group B streptococci)

confirmed infection: Escherichia coli and other gram-negative Enterobacteriaceae

confirmed infection: Listeria monocytogenes

confirmed infection: Staphylococcus aureus

confirmed infection: Staphylococcus epidermidis

confirmed infection: Pseudomonas aeruginosa

confirmed infection: Enterococcus species

confirmed infection: Acinetobacter species

confirmed infection: Neisseria meningitidis

Contributors

Expert advisers

Rodrigo Hasbun, MD, MPH

Professor of Medicine

UT Health Mc Govern Medical School

Houston, TX

Disclosures

RH has received research support and personal fees from Biomeriaux. RH is an author of references cited in this topic.

Omaima El Tahir, MD

PhD Candidate

Department of Pediatric infectious Diseases and Immunology, AI&II

Amsterdam UMC, Vrije Universiteit Amsterdam

Amsterdam

The Netherlands

Disclosures

OET declares that she has no competing interests.

Acknowledgements

Dr Rodrigo Hasbun and Omaima El Tahir would like to gratefully acknowledge Dr Marceline Tutu van Furth, previous contributor to this topic.

Disclosures

AMTvF declares that she has no competing interests.

Peer reviewers

Catherine Derber, MD

Professor

Department of Medicine

Eastern Virginia Medical School

Norfolk, VA

Disclosures

CD declares that she has no competing interests.

Guy Thwaites, MA, MBBS, PhD, MRCP, FRCPath

Wellcome Trust Clinical Research Fellow

Centre for Molecular Microbiology and Infection

Imperial College London

London

UK

Disclosures

GT declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Hasbun R. Progress and challenges in bacterial meningitis: a review. JAMA. 2022 Dec 6;328(21):2147-54. Abstract

van de Beek D, Cabellos C, Dzupova O, et al. ESCMID guideline: diagnosis and treatment of acute bacterial meningitis. Clin Microbiol Infect. 2016 May;22(suppl 3):S37-62.Full text  Abstract

Brouwer MC, McIntyre P, Prasad K, et al. Corticosteroids for acute bacterial meningitis. Cochrane Database Syst Rev. 2015 Sep 12;(9):CD004405.Full text  Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
  • Bacterial meningitis images
  • Differentials

    • Encephalitis
    • Viral meningitis
    • Drug-induced meningitis
    More Differentials
  • Guidelines

    • 2017 Infectious Diseases Society of America's clinical practice guidelines for healthcare-associated ventriculitis and meningitis
    • ESCMID guideline: diagnosis and treatment of acute bacterial meningitis
    More Guidelines
  • Videos

    Diagnostic lumbar puncture in adults: animated demonstration

    Venepuncture and phlebotomy: animated demonstration

    More videos
  • Patient information

    Meningitis and septicemia

    Pneumococcal vaccine in babies and children

    More Patient information
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