Suspected bacterial meningitis in an adult
Adult, community-acquired. Fever, headache, neck stiffness, altered mental state or purpuric rash. Emergency: antibiotics within 1 hour of arrival.
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Infectious DiseaseEmergency
Bacterial Meningitis in Adults (Community-Acquired)
Bacterial Meningitis in Adults (Community-Acquired): Suspected bacterial meningitis in an adult → Not for children, neonates or post-neurosurgery mening...
Pathway Overview
19 steps
Algorithm Steps
19 total
01Start 02Warning Not for children, neonates or post-neurosurgery meningitis
These patients need a different pathway or specialist advice.
- Children and neonates: use the paediatric meningitis pathway
- Neurosurgery, CSF shunt or drain, head trauma or CSF leak: different organisms; get ID and neurosurgery advice
- Immunocompromised: CT before LP, add Listeria cover, get ID advice (other organisms possible)
03Action Resuscitate, then take blood cultures now
ABC first. Tests must not delay antibiotics beyond 1 hour.
- Treat shock and sepsis; ICU review if shock, falling GCS or seizures
- Record GCS, focal signs, seizures, pupils, papilloedema, purpuric rash
- Blood cultures (2 sets) before antibiotics, if this causes no delay
- Also: blood glucose, FBC, coagulation, UEC, lactate, blood PCR for meningococcus and pneumococcus, HIV test
04Warning Do not do LP first if any of these
Give dexamethasone and antibiotics first. Do the LP later, when safe.
- Shock, respiratory failure, or extensive or rapidly spreading purpura
- Focal signs, new or uncontrolled seizures, papilloedema, GCS 12 or less, severe immunocompromise or known CNS lesion: CT head before LP (give antibiotics before CT)
- Anticoagulant, coagulopathy, platelets below 40 x 10^9/L, or infection at the LP site
05Action LP now only if safe and it will not delay antibiotics
If LP is unsafe or delayed, give dexamethasone and antibiotics first (next steps) and do the LP when safe.
- Blood glucose just before LP (for the CSF to blood glucose ratio)
- Measure opening pressure
- CSF: cell count, protein, glucose, Gram stain, culture, bacterial and viral PCR
- LP after antibiotics: CSF PCR can still identify the organism
06Warning Before antibiotics: check allergy, pregnancy and kidney function
Do not delay treatment while you check.
- Life-threatening penicillin or cephalosporin allergy (for example anaphylaxis): moxifloxacin 400 mg IV 24-hourly instead of ceftriaxone; add vancomycin on the same criteria as in the antibiotic step; get ID advice now on Listeria cover (co-trimoxazole). Non-severe penicillin allergy: ceftriaxone can be used
- Pregnant: add amoxicillin for Listeria; get obstetric advice
- Kidney impairment: adjust amoxicillin, vancomycin, aciclovir and meropenem doses
07Action Dexamethasone 10 mg IV just before or with the first antibiotic dose (adult)
Not for suspected meningococcal septicaemia without signs of meningitis. Continue 10 mg IV 6-hourly for 4 days if pneumococcus is confirmed or likely.
- Do not delay antibiotics to give dexamethasone
- Antibiotics already started: give dexamethasone as soon as possible, up to 4 hours after the first dose (Australian guidance; NICE allows up to 12 hours). Later: get ID advice
- Stop dexamethasone if meningococcus, Listeria or another organism is found (continue for pneumococcus or H. influenzae type b)
- No organism found: get ID advice on whether to continue
08Action Empiric antibiotics within 1 hour of arrival (adult)
Start now. Do not wait for CT or CSF results.
- Ceftriaxone 2 g IV 12-hourly
- Add amoxicillin 2 g IV 4-hourly for Listeria if age over 50, pregnant, immunocompromised, alcohol dependence or other major comorbidity
- Add vancomycin if Gram-positive cocci on CSF Gram stain, LP not possible, otitis media or sinusitis, recent beta-lactam treatment, or resistant pneumococcus possible (recent travel). Adult: load 25 to 30 mg/kg IV (max 2.5 g), then 15 to 20 mg/kg (max 2 g) 12-hourly, by actual body weight; adjust by levels and kidney function
- Suspected herpes simplex encephalitis (behaviour change, focal signs or seizures): add aciclovir 10 mg/kg IV 8-hourly (adult; adjust for kidney function). Obese: actual-weight dosing gives higher levels; use the local protocol for dosing weight
09Action Suspected meningococcal disease: droplet precautions and notify now
Notify the public health unit by phone on clinical suspicion. Do not wait for results.
- Droplet precautions until 24 hours of effective antibiotics
- Public health unit identifies close contacts and advises prophylaxis
- Contact prophylaxis (adult): ciprofloxacin 500 mg oral once; pregnant: ceftriaxone 250 mg IM once
- Patient not treated with ceftriaxone: ciprofloxacin 500 mg oral once to clear carriage
10Decision CSF Gram stain, culture or PCR result?
Typical bacterial CSF: turbid, raised white cells (often over 100 x 10^6/L, mainly neutrophils), protein over 0.4 g/L, CSF to blood glucose ratio 0.36 or less. A negative Gram stain does not exclude bacterial meningitis.
- Gram-positive diplococci
11Action Gram-positive diplococci or pneumococcus: ceftriaxone plus vancomycin
Likely Streptococcus pneumoniae.
- Continue ceftriaxone 2 g IV 12-hourly, plus vancomycin until ceftriaxone and penicillin MICs are known
- Penicillin MIC 0.06 mg/L or less: can change to benzylpenicillin 2.4 g IV 4-hourly
- Continue dexamethasone for 4 days
- Duration: 10 days if recovered; 14 days if slow response or resistant strain
12Warning Watch for complications
Reassess GCS and neurology often.
- Falling GCS, new focal signs or seizures: urgent CT; ICU and neurosurgery review
- Look for hydrocephalus, subdural empyema, abscess, venous sinus thrombosis
- Do not restrict fluids routinely; monitor sodium
13Decision Improving within 48 hours?
Fever, conscious state and neurology improving.
- If Yes
14Outcome Improving: complete the organism-specific course
Arrange a hearing test before discharge. Check that public health notification is done.
If No15Warning Not improving at 48 hours: re-image and get ID advice
Look for a complication, a resistant organism or another diagnosis.
- Repeat brain imaging (MRI or CT) for abscess, empyema or hydrocephalus
- Consider repeat LP (for example resistant pneumococcus)
- Review organism, susceptibility, drug doses and neurosurgery need
- Gram-negative diplococci
16Action Gram-negative diplococci or meningococcus: ceftriaxone, stop dexamethasone
Likely Neisseria meningitidis. Notify public health if not done.
- Continue ceftriaxone 2 g IV 12-hourly (benzylpenicillin 2.4 g IV 4-hourly if susceptible)
- Stop dexamethasone
- Duration: 5 to 7 days
- Public health unit arranges contact prophylaxis
- Path rejoins step 12Shared downstream outcome
- Gram-positive bacilli
17Action Gram-positive bacilli or Listeria: amoxicillin for at least 21 days
Likely Listeria monocytogenes. Ceftriaxone does not treat Listeria.
- Amoxicillin 2 g IV 4-hourly
- Stop dexamethasone
- Get ID advice on adding a second drug (co-trimoxazole or gentamicin)
- Stop ceftriaxone when Listeria is confirmed and no other organism
- Path rejoins step 12Shared downstream outcome
- Gram-negative bacilli
18Action Gram-negative bacilli: get ID advice
H. influenzae or Enterobacterales. Treat by susceptibility.
- H. influenzae: continue ceftriaxone 2 g IV 12-hourly for 7 to 10 days
- Enterobacterales: ceftriaxone if susceptible; ESBL risk: meropenem 2 g IV 8-hourly (adjust for kidney function; takes valproate: get ID advice); treat for 21 days
- Stop dexamethasone unless H. influenzae type b
- Path rejoins step 12Shared downstream outcome
- Gram stain negative or no CSF
19Action Gram stain negative or no CSF yet: continue full empiric treatment
Wait for CSF and blood culture and PCR. Many bacterial cases have a negative Gram stain.
- Continue ceftriaxone, and amoxicillin if Listeria risk; continue vancomycin if started, until results are known
- Continue dexamethasone only if pneumococcus is still likely; get ID advice
- Consider viral, TB, fungal and non-infective causes
- No organism and patient recovered: usual duration 10 days (ID advice)
- Path rejoins step 12Shared downstream outcome
Guideline Source
NICE NG240 Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management (2024)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults with community-acquired meningitis only. Not for children, neonates or healthcare-associated meningitis (neurosurgery, shunts, drains).
- Empiric choices assume low pneumococcal ceftriaxone resistance, as in Australia. Follow local guidance and get ID advice for every case.
- Adult doses assume normal kidney function; adjust amoxicillin, vancomycin, aciclovir and meropenem.
- Severe beta-lactam allergy: moxifloxacin is given as the Australian alternative, with vancomycin on the usual criteria; Listeria cover needs ID advice.
- CSF results need clinical correlation; a normal or negative Gram stain does not exclude bacterial meningitis.
Contraindicated Populations
NeonatesChildren (under 16 years): use the paediatric meningitis pathwayHealthcare-associated meningitis or ventriculitis (neurosurgery, CSF shunt or drain, head trauma with CSF leak)
Applicable Regions
AUUKEUUSInternational
AU: Australian Therapeutic Guidelines: ceftriaxone 4 g daily in divided doses; add vancomycin if Gram-positive cocci on Gram stain, otitis media or sinusitis, recent beta-lactam treatment or LP contraindicated; add Listeria cover if at risk (Safer Care Victoria 2025 uses benzylpenicillin 2.4 g IV 4-hourly). Meningococcal disease is urgently notifiable to the public health unit. IV chloramphenicol is not on the ARTG; for life-threatening penicillin allergy use moxifloxacin 400 mg IV daily (Safer Care Victoria 2025).
EU: ESCMID 2016 acute bacterial meningitis guideline: add vancomycin or rifampicin where pneumococcal resistance is common.
UK: NICE NG240 (2024) and UK joint specialist societies adult guideline (2016).
US: IDSA 2004 adds vancomycin to ceftriaxone for all adults empirically.
International: Where resistance or drug supply differs, follow local guidance.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Bacterial Meningitis in Adults (Community-Acquired)?
The Bacterial Meningitis in Adults (Community-Acquired) is a emergency clinical algorithm for Infectious Disease. It provides a structured decision tree to guide clinical decision-making, based on NICE NG240 Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management (2024).
What guideline is the Bacterial Meningitis in Adults (Community-Acquired) based on?
This algorithm is based on NICE NG240 Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management (2024).
What are the limitations of the Bacterial Meningitis in Adults (Community-Acquired)?
Known limitations include: Adults with community-acquired meningitis only. Not for children, neonates or healthcare-associated meningitis (neurosurgery, shunts, drains).; Empiric choices assume low pneumococcal ceftriaxone resistance, as in Australia. Follow local guidance and get ID advice for every case.; Adult doses assume normal kidney function; adjust amoxicillin, vancomycin, aciclovir and meropenem.; Severe beta-lactam allergy: moxifloxacin is given as the Australian alternative, with vancomycin on the usual criteria; Listeria cover needs ID advice.; CSF results need clinical correlation; a normal or negative Gram stain does not exclude bacterial meningitis.. Individual patient factors may require deviation from these recommendations.
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