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# Bacterial meningitis

Bacterial meningitis is an infection of the membranes around the brain and [spinal cord](https://durgical.com/en/anatomy/spinal-cord/); it causes fever, headache and stiff neck and is an emergency.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [Dura mater](https://durgical.com/en/anatomy/cranial-dura/)
- [Superior sagittal sinus](https://durgical.com/en/anatomy/superior-sagittal-sinus/)
- [Choroid plexus](https://durgical.com/en/anatomy/choroid-plexus/)
- [Vestibulocochlear nerve (VIII)](https://durgical.com/en/anatomy/vestibulocochlear-nerve/)
- [Nasal cavity](https://durgical.com/en/anatomy/nasal-cavity/)
- [Cribriform plate](https://durgical.com/en/anatomy/cribriform-plate/)

## Microorganisms that cause it

- [Neisseria meningitidis](https://durgical.com/en/microbiology/neisseria-meningitidis/)
- [Escherichia coli](https://durgical.com/en/microbiology/escherichia-coli/)
- [Haemophilus influenzae](https://durgical.com/en/microbiology/haemophilus-influenzae/)
- [Streptococcus pneumoniae](https://durgical.com/en/microbiology/streptococcus-pneumoniae/)
- [Streptococcus agalactiae](https://durgical.com/en/microbiology/streptococcus-agalactiae/)
- [Listeria monocytogenes](https://durgical.com/en/microbiology/listeria-monocytogenes/)

## In immunology

- [Complement deficiencies and hereditary angioedema](https://durgical.com/en/immunology/complement-deficiencies-and-hereditary-angioedema/)
- [Colombia's PAI schedule (which vaccines, at what age)](https://durgical.com/en/immunology/colombia-s-pai-schedule/)

## In histology

- [Gray and white matter, cerebellar cortex, meninges](https://durgical.com/en/histology/gray-and-white-matter-cerebellar-cortex-meninges/)
- [Blood–brain barrier, choroid plexus and cerebrospinal fluid](https://durgical.com/en/histology/blood-brain-barrier-choroid-plexus-and-cerebrospinal-fluid/)

## In the clinical exam

- [Meningeal signs: neck stiffness, Kernig and Brudzinski](https://durgical.com/en/clinical-exam/meningeal-signs-neck-stiffness-kernig-and-brudzinski/)
- [Intracranial hypertension syndrome](https://durgical.com/en/clinical-exam/intracranial-hypertension-syndrome/)
- [Meningeal syndrome](https://durgical.com/en/clinical-exam/meningeal-syndrome/)

## In physiology

- [CSF and the blood–brain barrier](https://durgical.com/en/physiology/csf-and-the-blood-brain-barrier/)
- [Headache physiology](https://durgical.com/en/physiology/headache-physiology/)

## Why it happens

- [Patterns of acute inflammation: serous, fibrinous, purulent, abscess, ulcer](https://durgical.com/en/general-pathology/patterns-of-acute-inflammation-serous-fibrinous-purulent-abscess-ulcer/)
- [How septic shock develops](https://durgical.com/en/general-pathology/how-septic-shock-develops/)
- [Cerebral blood flow, brain metabolism and intracranial pressure](https://durgical.com/en/physiology/cerebral-blood-flow-brain-metabolism-and-intracranial-pressure/)

## What it is

Acute bacterial infection of the meninges and the cerebrospinal fluid around the brain and spinal cord. It is a medical emergency that can kill or disable within hours.

## Who gets it

Highest in infants, young children and older adults. Conjugate vaccines included in national immunisation programmes, such as Colombia's, have reduced Haemophilus influenzae type b and pneumococcal disease.

## Causes

- Streptococcus pneumoniae (commonest in adults)
- Neisseria meningitidis
- Haemophilus influenzae type b (now rare where vaccinated)
- Listeria monocytogenes in neonates, older adults and immunosuppressed
- Group B streptococcus and Escherichia coli in neonates

## Risk factors

- Extremes of age
- Lack of vaccination
- Otitis media, sinusitis or pneumonia
- Skull base fracture or CSF leak, cochlear implants
- Asplenia, HIV and other immunosuppression, alcohol use
- Crowded settings (meningococcus)

## Pathophysiology

Bacteria colonise the nasopharynx, enter the bloodstream and cross into the subarachnoid space, or spread directly from nearby infection or a skull defect. Bacterial products trigger an intense inflammatory response that causes cerebral oedema, vasculitis, raised intracranial pressure and neuronal injury.

## Symptoms and signs

- Fever
- Headache
- Neck stiffness
- Altered mental status
- Photophobia, vomiting, seizures
- Petechial or purpuric rash (meningococcus)
- Infants: irritability, poor feeding, bulging fontanelle

## Red flags

- Non-blanching purpuric rash or shock
- Falling consciousness or focal signs
- Seizures
- Any delay to antibiotics

## Diagnosis

**Clinical**
The classic triad of fever, neck stiffness and altered mental status is present in only a minority, but nearly all have at least one feature with headache. Kernig and Brudzinski signs have low sensitivity.

**Tests**
Blood cultures before antibiotics, then lumbar puncture: high opening pressure, neutrophils, high protein, low glucose ratio; Gram stain, culture and PCR. Blood count, CRP, lactate.

**Imaging**
Head CT before lumbar puncture only in selected patients (focal signs, reduced consciousness, papilloedema, immunosuppression, new seizure); antibiotics are not delayed for it.

## Differential diagnosis

- Viral meningitis or encephalitis
- Subarachnoid haemorrhage
- Tuberculous or fungal meningitis
- Brain abscess
- Sepsis from another source
- Cerebral malaria

## Goal of treatment

Give effective antibiotics immediately, reduce inflammation-related damage, support the circulation and brain, and protect close contacts.

## Treatment

**Acute**
Empirical intravenous antibiotics without delay: third-generation cephalosporins, plus vancomycin where pneumococcal resistance is a concern, plus ampicillin when Listeria is possible. Adjusted to cultures.

**Medical**
Corticosteroids (dexamethasone class) given with or before the first antibiotic dose in suspected pneumococcal meningitis, as many guidelines advise.

**Follow-up**
Intensive care for shock, raised intracranial pressure and seizures; fluid and sodium monitoring.

**Medical**
Antibiotic prophylaxis for close contacts of meningococcal and Hib cases, according to public health guidance.

**Rehabilitation**
Hearing testing after recovery, with cochlear implants if needed; neurodevelopmental follow-up in children.

## Drugs for this condition

- [Ampicillin](https://durgical.com/en/pharmacology/ampicillin/)
- [Ceftazidime](https://durgical.com/en/pharmacology/ceftazidime/)
- [Cefotaxime](https://durgical.com/en/pharmacology/cefotaxime/)
- [Vancomycin](https://durgical.com/en/pharmacology/vancomycin/)
- [Meropenem](https://durgical.com/en/pharmacology/meropenem/)
- [Polymyxin B](https://durgical.com/en/pharmacology/polymyxin-b/)
- [Chloramphenicol](https://durgical.com/en/pharmacology/chloramphenicol/)
- [Ceftriaxone](https://durgical.com/en/pharmacology/ceftriaxone/)
- [Haemophilus influenzae type b (Hib) vaccine](https://durgical.com/en/pharmacology/haemophilus-influenzae-type-b-vaccine/)
- [Pneumococcal vaccine](https://durgical.com/en/pharmacology/pneumococcal-vaccine/)
- [Meningococcal vaccine](https://durgical.com/en/pharmacology/meningococcal-vaccine/)

## Complications

- Septic shock and disseminated intravascular coagulation
- Cerebral oedema and herniation
- Sensorineural hearing loss
- Seizures and hydrocephalus
- Limb loss after meningococcal purpura fulminans
- Cognitive and developmental deficits

## Prognosis

Mortality remains significant even with treatment, highest with pneumococcus and in older adults. Many survivors have lasting effects, especially hearing loss. Delay to antibiotics worsens outcome.

## Prevention

- Conjugate vaccines against Hib, pneumococcus and meningococcus
- Chemoprophylaxis of close contacts
- Antenatal screening and intrapartum prophylaxis for group B streptococcus
- Prompt treatment of ear and sinus infections

## Test yourself

Think of the answer, then tap the question to see it.

## What is the classic triad of bacterial meningitis?

Fever, neck stiffness and altered mental status; all three are present in only a minority.

## What CSF profile suggests bacterial meningitis?

Raised neutrophils, high protein, low CSF-to-blood glucose ratio and high opening pressure.

## Should antibiotics wait for a CT scan or lumbar puncture?

No. Blood cultures are taken and empirical antibiotics are started immediately.

## Which antibiotic is added when Listeria is a concern?

Ampicillin, for neonates, older adults, pregnant and immunosuppressed patients.

## What is the commonest long-term complication in survivors?

Sensorineural hearing loss.

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## Related conditions

- [Subarachnoid haemorrhage](https://durgical.com/en/conditions/subarachnoid-haemorrhage/)
- [Epilepsy and seizures](https://durgical.com/en/conditions/epilepsy-and-seizures/)
- [Community-acquired pneumonia](https://durgical.com/en/conditions/community-acquired-pneumonia/)
- [Neurocysticercosis](https://durgical.com/en/conditions/neurocysticercosis/)
- [Acute otitis media](https://durgical.com/en/conditions/acute-otitis-media/)
- [Acute rhinosinusitis](https://durgical.com/en/conditions/acute-rhinosinusitis/)
- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Bacterial Meningitis](https://www.ncbi.nlm.nih.gov/books/NBK470351/) (StatPearls (NCBI Bookshelf), 2023).

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Source: https://durgical.com/en/conditions/bacterial-meningitis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/bacterial-meningitis/