Illustration: pairs of round bacteria caught in a fine meshwork as an immune cell approaches.
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Bacterial meningitis

Updated Oct 20, 2026Adults · ED management23 sources · 17 checked in PubMed2 figuresNICE NG240 2024

Bottom line

  • The classic triad is often missing. Fever, neck stiffness and altered mental status occurred together in only 44% of adults with culture-proven disease, but 95% had at least two of headache, fever, neck stiffness and altered mental status.2
  • Antibiotics within 1 hour of arrival. Take blood cultures first. Do the lumbar puncture before antibiotics only if it is safe and causes no meaningful delay.1
  • Don't scan first and treat later. A door-to-antibiotic time over 6 hours was linked to higher mortality (OR 8.4), and doing CT, then LP, then antibiotics was one of the factors linked to that delay.10
  • Give dexamethasone with or before the first antibiotic dose. In adults it cut unfavorable outcomes (RR 0.59), most clearly in pneumococcal meningitis.18
  • Cover resistant pneumococcus and Listeria. Where ceftriaxone-resistant pneumococcus exceeds 1%, use vancomycin plus ceftriaxone. Add ampicillin for older and immunocompromised patients.6

Recognize

  • Strongly suspect it when fever, headache, neck stiffness and altered consciousness or cognition occur together. It can still be strongly suspected without all four.1
  • The triad is insensitive. In 696 Dutch episodes, the triad of fever, neck stiffness and altered mental status was present in only 44%. At least two of the four symptoms (adding headache) were present in 95%.2
  • Absence of all three of fever, neck stiffness and altered mental status makes meningitis very unlikely. In a pooled review, 99–100% of patients had at least one of them.3
  • Easy to miss in older adults, who are less often febrile, and in young adults whose confusion is blamed on alcohol or drugs.1
  • Look for a non-blanching rash over the whole body and in the conjunctivae. Purpura larger than 2 mm, or a spreading petechial rash, means meningococcal disease until proven otherwise. No rash does not rule it out.1
  • Risk factors: missed vaccines, absent or poorly functioning spleen, complement deficiency, student housing, recent contact with meningococcal or Hib disease, a past episode, a CSF leak, or a cochlear implant.1

Bedside signs

SignSensitivitySpecificitySource
Kernig sign2%97%ED cohort, n = 2304
Brudzinski sign2%98%ED cohort, n = 2304
Nuchal rigidity13%80%ED cohort, n = 2304
Jolt accentuation of headache21%82%ED cohort, n = 197 with headache4
Jolt accentuation (pooled)65.3%70.4%9 studies, very low certainty5

Reference standard was CSF pleocytosis in neurologically intact adults having a lumbar puncture.4 A positive sign raises suspicion; a negative one rules nothing out.4,5

Sources disagree

An early review reported jolt accentuation as 100% sensitive in patients with fever and headache.3 Later studies did not reproduce this: 21% in one ED cohort and 65% pooled across nine studies.4,5 Don't use a negative jolt test to skip the lumbar puncture.

Who causes it

  • In people older than 16, Streptococcus pneumoniae causes about 72% of cases and Neisseria meningitidis about 11%. Older age and immunosuppression are risk factors.6
  • In 1,412 Dutch adult episodes (2006–14), pneumococcus caused 72%. Incidence fell as children's conjugate vaccines took hold.7

First hour

  1. Get a senior clinician to assess now. Aim for antibiotics within 1 hour of arrival.1
  2. Stabilize first: treat an unprotected airway, respiratory compromise, shock, uncontrolled seizures or a bleeding risk before any lumbar puncture.1
  3. Take blood: blood cultures, white cell count, CRP (or procalcitonin), glucose and whole-blood PCR, plus an HIV test. Swab the throat for meningococcal culture, ideally before antibiotics.1
  4. Lumbar puncture before antibiotics only if it is safe and quick. Otherwise give antibiotics and do it as soon as it is safe. Check blood glucose right before the tap.1
  5. Give dexamethasone with or just before the first antibiotic dose, but never hold antibiotics to wait for it.1,9
  6. Give IV antibiotics (table below).1,6
  7. If imaging is needed, treat first. Take bloods, give antibiotics and stabilize before the scan.1
FIG 1The meningitis clock. Drawn for this page from cited data. Antibiotics are due within 1 hour of arrival.1 A door-to-antibiotic time over 6 hours was linked to higher mortality.10 Dexamethasone goes with or before the first antibiotic dose. If it was missed, give it as soon as possible up to 12 hours after antibiotics started.1 CSF cell counts, protein and glucose should be back within 4 hours of the lumbar puncture.1

CT before lumbar puncture?

NICE 2024: image first ifIDSA 2004: image first if
Risk factors for an evolving mass lesionImmunocompromise
New focal neurological signs, including seizures or posturingSeizure within the past week
Abnormal pupil reactionsPapilledema
GCS 9 or less, or a sustained or rapid fall in consciousnessA specific neurologic abnormality

NICE advises against routine imaging before lumbar puncture.1 The IDSA criteria are a B-II recommendation, taken from the official summary.8,9 With either approach, take blood cultures and give antibiotics before the scan.1,9

  • Clinical features predict a normal CT. In 301 adults with suspected meningitis, 235 had a CT first. 24% were abnormal and 5% showed mass effect. When none of the high-risk features were present, 93 of 96 scans were normal (negative predictive value 97%).11
  • The high-risk features were age 60 or older, immunocompromise, known CNS disease, a seizure in the past week, an abnormal level of consciousness, failing two consecutive questions or commands, gaze palsy, a visual field defect, facial palsy, arm or leg drift, and aphasia.11
  • Prompt LP did better in a national cohort. In 815 Swedish adults, LP without imaging first was associated with lower mortality (aOR 0.38) and more favorable outcomes (aOR 2.11), even with altered mental status or immunosuppression.12
  • A normal CT does not mean the LP is safe. Up to 80% of meningitis patients who herniate had no CT abnormality, and pre-LP CT is linked to antibiotic delays.13
Sources disagree

Who needs a CT first varies widely. In the Swedish cohort, imaging was indicated for 7% of patients under Swedish rules, 32% under the European (ESCMID) guideline and 65% under IDSA.12 NICE limits imaging to signs of raised intracranial pressure or a possible mass lesion.1 Whatever you choose, antibiotics come first.1,10

Reading the CSF

CSFNormalBacterialViral
Opening pressure6–25 cm H₂OOften > 20–30Normal or slightly raised
AppearanceClearTurbid or cloudyClear
White cells< 5/µL100–10,000/µL, often > 1,00010–1,000/µL, usually < 250–500
Main cell typeLymphocytesNeutrophils*Lymphocytes
Protein15–45 mg/dL> 100 mg/dLNormal or mildly raised
Glucose≥ 45 mg/dL (2.5 mmol/L)Often < 40 mg/dL (2.2 mmol/L)Usually normal
CSF:serum glucose~0.6< 0.4> 0.5–0.6

Adapted from LITFL, with protein and glucose converted to US units.14 *Lymphocytes may predominate early or after antibiotics.14 Use standard age-appropriate thresholds, allowing for prior antibiotics or immunodeficiency.1

  • Send: cell count with differential, protein, glucose (with the paired blood glucose), Gram stain, culture and PCR. Keep the leftover fluid for extra tests.1
  • Thresholds that suggest bacterial disease in one review: serum white cells > 10,000/µL, CSF white cells > 2,000/µL, CSF neutrophils > 1,180/µL, CSF protein > 220 mg/dL, or CSF glucose below about 34 mg/dL.6
  • Gram stain: a positive result is diagnostic, but sensitivity is only 50–90%.6
  • CSF lactate separated bacterial from aseptic meningitis better than glucose, protein or cell count in a meta-analysis of 25 studies (area under the curve 0.98).15 The 2004 IDSA guideline did not recommend it for routine use.9
  • Prior antibiotics make CSF results less reliable. Red cells in the sample may mean a traumatic tap or another diagnosis.1
  • Blood tests can't rule it out. A normal CRP, procalcitonin or white cell count does not exclude bacterial meningitis.1
Microscope image of a Gram-stained spinal fluid sample showing many pink neutrophils and tiny paired round bacteria scattered between them
FIG 2Gram stain of CSF, ×1000. Many neutrophils, with small paired cocci (Gram-negative diplococci) scattered among them. Neisseria meningitidis grew in culture.Microman12345 · Wikimedia Commons · CC BY-SA 4.0

Treatment

DrugAdult doseWhenNotes
Empiric antibiotics
Ceftriaxone IVTop of the label range: up to 4 g/day, given once daily or split twice dailyEveryoneNICE advises the highest recommended dose. The label's general adult range is 1–2 g/day. Don't mix with calcium-containing solutions.1,16
Vancomycin IVDose per institutional protocol and labelWhere ceftriaxone-resistant pneumococcus exceeds 1%Given with ceftriaxone. Not recommended alone.6,9
Ampicillin IV150–200 mg/kg/day, divided every 3–4 h (label)Older or immunocompromised adults (Listeria risk)NICE uses IV amoxicillin for the same purpose.1,6,17
Adjunct
Dexamethasone IV0.15 mg/kg every 6 h for 2–4 days (IDSA); 10 mg every 6 h for 4 days in the main adult trialWith or 10–20 min before the first antibiotic doseContinue for pneumococcus (and Hib); stop for other organisms.1,9,18
Special situations
Severe beta-lactam allergyChloramphenicol; get infection specialist advice—Add co-trimoxazole if Listeria is a risk (NICE).1
MeropenemDose per institutional protocol and labelAlternative to ceftriaxoneIDSA A-I as an alternative agent.9
AciclovirNot routineOnly if HSV encephalitis is strongly suspected1

Unreviewed doses. Verify against the current label and your institution's protocol before giving anything.

Ceftriaxone and ampicillin doses come from their FDA labels.16,17 The vancomycin label gives no meningitis dose, and the meropenem label covers meningitis only in children, so neither dose is stated here. Get infection specialist advice for every confirmed case, especially after travel or with known resistant organisms.1

Sources disagree

Empiric vancomycin. NICE recommends ceftriaxone alone when the organism is unknown.1 IDSA advises choosing empiric therapy that assumes antimicrobial resistance.9 A 2022 review recommends vancomycin plus ceftriaxone where ceftriaxone-resistant pneumococcus exceeds 1%.6 Use the regimen that fits local resistance.

Dexamethasone

  • Adult trial: in 301 European adults, dexamethasone 10 mg every 6 hours for 4 days lowered unfavorable outcomes (RR 0.59) and death (RR 0.48). In pneumococcal meningitis, unfavorable outcomes fell from 52% to 26%. GI bleeding was not increased.18
  • Cochrane review (25 trials, 4,121 patients): no significant overall reduction in death (17.8% vs 19.9%), but less severe hearing loss (RR 0.67) and fewer neurological sequelae. Mortality fell in pneumococcal meningitis (RR 0.84). Benefit was seen in high-income countries, not low-income ones.19
  • Individual patient meta-analysis (2,029 patients, 29% with confirmed or likely HIV): no reduction in death (26.5% vs 27.2%), though survivors had less hearing loss (24.1% vs 29.5%).20
  • Real-world use: after the Netherlands adopted dexamethasone, it was given in 89% of episodes and was linked to fewer unfavorable outcomes (adjusted OR 0.54).7
  • Stop it if Listeria is confirmed.6
Sources disagree

Antibiotics already given? IDSA says not to start dexamethasone, because it is unlikely to help.9 NICE says to give it as soon as possible if fewer than 12 hours have passed since antibiotics started. After 12 hours, ask an infection specialist.1

Supportive care

  • Fluids: don't routinely restrict below maintenance.1
  • Raised intracranial pressure: no glycerol, and no routine mannitol or hypertonic saline. If herniation is a concern, consider an osmotic agent as a temporary measure and call critical care urgently.1
  • Meningococcal sepsis: no routine steroids. Consider low-dose replacement steroids for shock that persists on high-dose vasopressors.1

Contacts and public health

  • Close contacts of invasive meningococcal disease need prophylaxis. First-line options are rifampin, ciprofloxacin or ceftriaxone. Health departments guide the local choice.21
  • Rifampin (label dose for clearing meningococcal carriage in adults): 600 mg twice daily for 2 days.22
  • Ciprofloxacin resistance is rising in the US. Where at least two resistant cases make up 20% or more of local cases in 12 months, health departments should use rifampin, ceftriaxone or azithromycin instead.21

Disposition and prognosis

  • Get infection specialist advice for every case of bacterial meningitis.1
  • Call critical care for signs of raised intracranial pressure or herniation.1
  • If you send someone home after assessment, explain which symptoms to watch for and when to come back, including a rash that stops blanching.1
  • Outcomes are poor. In the 1998–2002 Dutch cohort, 21% died, and pneumococcal disease was deadlier than meningococcal disease (30% vs 7%).2 In 2006–14, 17% died and 38% had an unfavorable outcome.7
  • Markers of a worse outcome include older age, tachycardia, a low GCS, cranial nerve palsy, a CSF white count under 1,000/µL, a positive blood culture and a high CRP.7

Pitfalls

  • Holding antibiotics until after the CT or the LP.1,10
  • Ruling meningitis out because the classic triad is missing.2
  • Trusting a negative Kernig, Brudzinski or jolt test.4,5
  • Being reassured by a normal white count or CRP.1
  • Forgetting dexamethasone, or giving it long after antibiotics without a plan.1,9
  • Leaving out ampicillin in older or immunocompromised patients.6
  • Blaming confusion in a young adult on alcohol or drugs.1

How strong is the evidence?

Antibiotic timing rests on observational data, not trials.10 The CT-before-LP question has cohort data but no randomized trial, and the decision rules have not been validated.11,12,13 Dexamethasone has the strongest support, from a randomized trial in adults, though pooled analyses that include low-income settings show less benefit.18,19,20 The US empiric regimen comes from a 2004 guideline that is now archived.8,9

On-shift teaching

Questions to ask a learner at the bedside. Tap a question to see the answer. Every answer uses facts cited above.

Q1How often is the classic triad present in adults with bacterial meningitis?
Only 44% had fever, neck stiffness and altered mental status together. But 95% had at least two of headache, fever, neck stiffness and altered mental status.2
Q2Can a negative Kernig or Brudzinski sign help rule out meningitis?
No. In an ED cohort each was only 2% sensitive for CSF pleocytosis, and nuchal rigidity was 13% sensitive.4
Q3A patient with suspected meningitis needs a CT first. What happens before the scan?
Bloods, antibiotics and stabilization.1 A door-to-antibiotic time over 6 hours was linked to higher mortality (OR 8.4), and doing CT, then LP, then antibiotics was one of the factors linked to that delay.10
Q4Which clinical features predicted an abnormal CT in adults with suspected meningitis?
Age 60 or older, immunocompromise, known CNS disease, a seizure in the past week, and neurological abnormalities such as altered consciousness, gaze or facial palsy, drift or aphasia. Without any of these, 93 of 96 CTs were normal.11
Q5What did the main adult dexamethasone trial show?
Dexamethasone 10 mg every 6 hours for 4 days, started with or before antibiotics, lowered unfavorable outcomes (RR 0.59) and death (RR 0.48). In pneumococcal meningitis, unfavorable outcomes fell from 52% to 26%.18
Q6Why add ampicillin for a 70-year-old, and when do you add vancomycin?
Ampicillin covers Listeria in older and immunocompromised patients. Vancomycin covers ceftriaxone-resistant pneumococcus where that resistance exceeds 1%.6

References

Evidence base

What this page is built on

23 sources, cited 117 times. Dots are sources, filled by how far each was read; stronger color means a larger share of the citations. Tap a tier to see its sources.

Read in full · 7Abstract read · 14Record only · 2Link checked · 0

Checked by the writer, not a physician. The dots show how each source was read, not that anyone has confirmed the claims.

How this page was made
  • Written from scratch. No source text was copied; facts are restated and cited.
  • Anchored on the NICE 2024 guideline (NG240), whose recommendations were read in full. NICE gives no antibiotic doses and defers to the British National Formulary, so doses here come from FDA labels on DailyMed. The vancomycin label gives no meningitis dose, and the meropenem label covers meningitis only in children, so no adult dose is stated for either.
  • The 2004 IDSA guideline is archived and its full text could not be retrieved. Its recommendations come from the official summary in American Family Physician, and both are cited. The summary did not include the guideline's empiric-therapy table, so the US empiric regimen is cited to a 2022 JAMA review. The 2016 ESCMID guideline could not be accessed and is listed as further reading only.
  • Each PubMed citation was resolved through NCBI E-utilities, and each number was checked against that paper's abstract. The CDC prophylaxis report was read in full in PubMed Central. A CDC clinical guidance page could not be fetched.
  • Adults only. NICE covers children and babies too, but dexamethasone, antibiotic choice and CSF thresholds differ in infants, and neonates follow a separate guideline. Use pediatric guidance for children.
  • Figure 1 was drawn for this page from cited time targets. Figure 2 is an openly licensed image from Wikimedia Commons, credited under it, and it keeps its own license.
  • Not for clinical use.
Not for clinical use

AI-generated draft. Not reviewed by a physician. This page is for education only and may contain errors, including in doses. Do not use it to diagnose, treat or make decisions about any patient. Rely on your own clinical judgment, your institution's protocols and current drug labeling. Reading this page does not create a physician-patient relationship. Full terms