Bacterial Meningitis
Clinical Snapshot
Bacterial meningitis is an infection of the leptomeninges — the arachnoid and pia mater surrounding the brain and spinal cord — that most often begins when bacteria colonizing the nasopharynx (chiefly Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae) invade the bloodstream and cross the blood-brain barrier.[1] Once bacteria reach the subarachnoid space, host defenses there are limited, and the resulting cytokine-driven inflammatory cascade — not the bacteria themselves — causes most of the neuronal injury, hearing loss, and long-term neurologic damage seen in survivors.[1] This is one of the few true pharmacotherapy emergencies in medicine: every hour that empiric antibiotics are delayed measurably worsens the odds of death or permanent disability, which is why treatment must never wait for a lumbar puncture, imaging, or a confirmed diagnosis.[2]
Recognize the Condition
Classic presentation (older children and adults)
Most adults with bacterial meningitis have at least 2 of the 4 classic features — headache, fever, neck stiffness (nuchal rigidity), and altered mental status — but the complete triad of fever, neck stiffness, and altered consciousness is present in only a minority, so its absence never excludes the diagnosis.[3]
Other common features include photophobia, vomiting, back pain, and a general sense of being acutely, systemically unwell. Neurologic symptoms — loss of balance, disorientation, confusion, and focal neurologic deficits — can occur at any age. A patient of any age may present in septic shock (decreased level of consciousness, hypotension, poor peripheral perfusion) rather than with the classic fever-and-headache picture, especially with fulminant meningococcemia.[1]
Meningeal signs
Nuchal rigidity — resistance to passive neck flexion — is the single most useful bedside meningeal sign in older children and adults, though it is frequently absent in neonates and infants with open fontanelles.
Kernig's sign is tested with the patient supine and the hip flexed to 90°: the sign is positive if the examiner cannot passively extend the knee beyond roughly 135° because of hamstring spasm and resistance, or if attempted extension reproduces pain.
Brudzinski's sign is tested with the patient supine: the sign is positive if passive flexion of the neck causes involuntary flexion of the hips and knees.
Both signs have limited sensitivity and can be absent even in confirmed bacterial meningitis — a negative Kernig's or Brudzinski's sign does not rule out the diagnosis and should never be used alone to decide against a lumbar puncture.[3]
Petechiae or purpura — non-blanching, irregular red-purple spots — strongly suggest meningococcal disease but can also occur with S. pneumoniae. Their presence in a patient with possible meningitis should be treated as a marker of septicemia and escalated accordingly.
Presentation varies markedly by age
Infants and children under 2 years, and any nonverbal patient
Presentation is frequently nonspecific: fever or hypothermia, lethargy or an altered level of consciousness, inconsolable or altered-quality crying, irritability, lack of response to social stimulation, poor feeding, vomiting, diarrhea, pallor, seizures, and a bulging anterior fontanelle (a late and insensitive sign). Meningeal signs are frequently absent in this age group even with confirmed disease.
Older children and adults
Fever, headache, nuchal rigidity or back pain, and photophobia predominate, usually with associated vomiting and a sense of being acutely, systemically unwell. Meningeal signs are more reliably present than in infants, though still not universal.
Risk Factors
- Extremes of age — infants under 12 months and adults over 70 years.
- Recent head or spinal trauma or surgery, cerebrospinal fluid (CSF) leak, or cochlear implant.
- Current or recent immunosuppressive therapy, including long-term prednisone (2 mg/kg/day or more for over 14 days), chemotherapy, and therapeutic monoclonal antibodies — particularly eculizumab and other terminal-complement inhibitors.
- Multiple myeloma, leukemia, or other malignancy.
- Functional or anatomic asplenia (e.g., sickle cell disease, splenectomy) and other hyposplenic states.
- Ventriculoperitoneal shunt, penetrating head trauma, or basilar skull fracture with CSF leak.
- Incomplete or absent immunization against Haemophilus influenzae type b, Streptococcus pneumoniae, or Neisseria meningitidis.
- Close contact (household, daycare, dormitory, or military-unit) with a case of invasive meningococcal or H. influenzae type b disease.
- A neonate born to a parent colonized with group B streptococcus who did not receive intrapartum antibiotic prophylaxis.
- Chronic alcohol use disorder — an independent risk factor specifically for Listeria monocytogenes meningitis.
- Crowded living conditions or travel to a region with a high burden of meningococcal disease (e.g., the sub-Saharan African meningitis belt, or mass gatherings such as the Hajj).
Red Flags & Refer
Any suspected bacterial meningitis is itself the red flag — this is a medical emergency requiring immediate empiric antibiotics, usually before the diagnosis is fully confirmed. Escalate immediately, and never delay antibiotics to arrange any of the following.
- Give empiric IV antibiotics within 1 hour of suspicion — this single delay is the most modifiable driver of death and disability in bacterial meningitis.[2]
- Signs of septic shock — hypotension, tachycardia, poor peripheral perfusion, or a decreased level of consciousness — need immediate resuscitation alongside antibiotics.
- A non-blanching petechial or purpuric rash suggests meningococcemia and mandates the same emergency response even before meningitis itself is confirmed.
- Signs of raised intracranial pressure or impending herniation — a new focal neurologic deficit, new-onset seizure, papilledema, or a decreasing or fluctuating level of consciousness — need urgent neuroimaging and neurosurgical/critical care involvement; do not perform a lumbar puncture until these are addressed.
- Cranial nerve palsies or other signs of brainstem involvement.
- Any acute complication of established meningitis — brain abscess, cerebritis or ventriculitis, cerebral infarction with hemiparesis or quadriparesis, subdural effusion or empyema, venous sinus thrombosis, hydrocephalus, or disseminated intravascular coagulopathy — needs immediate neurology/neurosurgery/critical care involvement.
- Failure to improve, or any clinical deterioration, despite 48–72 hours of appropriate empiric therapy — needs repeat imaging and reassessment, not simply more time on the same regimen.
- Suspected healthcare-associated meningitis (recent neurosurgery, ventriculoperitoneal shunt, or penetrating head trauma) needs neurosurgical involvement in addition to antimicrobial therapy.
Assessment & Diagnosis
History
Ask about onset and duration of symptoms (most patients present within 24 hours of symptom onset), recent respiratory illness, recent head/spinal trauma or neurosurgery, immunosuppression, asplenia, alcohol use, recent antimicrobial use (which can blunt or mask typical signs and CSF findings), sick contacts, and immunization history.
Examination
Vital signs frequently show tachycardia and tachypnea; blood pressure may be normal or low, especially with septic shock. Look specifically for nuchal rigidity, Kernig's and Brudzinski's signs (see Recognize the Condition), level of consciousness, focal neurologic deficits, cranial nerve palsies, papilledema, and a petechial/purpuric rash. In patients already on antimicrobials, signs may be attenuated or atypical.
Clinical prediction tools
Several clinical prediction models exist to help distinguish bacterial from viral meningitis, but guidance is mixed on their use — some sources support them as an adjunct, others recommend against routinely relying on them. Clinical judgment, not a scoring tool, should drive the decision to start empiric antibiotics; no validated score is precise enough to safely withhold treatment from a patient who otherwise looks unwell.[2]
Lumbar puncture and cerebrospinal fluid analysis
Examination of the CSF is essential to the diagnosis and should be obtained whenever meningitis is clinically suspected, unless a specific contraindication is present.
Lumbar puncture is contraindicated in the presence of: raised intracranial pressure (suggested by focal neurologic signs, new-onset seizure, altered or deteriorating consciousness, or papilledema), active seizures, shock, coagulopathy, or infection at the proposed puncture site. When raised intracranial pressure is strongly suspected clinically, obtain a CT scan before the LP — but draw blood cultures and give antibiotics (plus dexamethasone, if indicated) before sending the patient for imaging, not after.[4]
Neuroimaging (CT or MRI) is also indicated, though not routinely required in every patient, for: focal neurologic signs, clinical evidence of brain herniation, a decreased or fluctuating level of consciousness, clinical deterioration, or persistent fever. Repeat imaging is indicated after starting therapy if any of these develop, or if the patient fails to improve as expected.
| CSF parameter | Finding consistent with bacterial meningitis |
|---|---|
| Appearance / opening pressure | Turbid or cloudy, with opening pressure above 20 cm H2O. |
| White blood cell count | Normal is under 5 x106/L; bacterial meningitis usually shows over 100 x106/L, and often over 1000 x106/L, with neutrophil predominance. Early in the illness the count may be much lower — a low CSF WBC does not exclude bacterial meningitis, especially soon after symptom onset. |
| Glucose (CSF-to-serum ratio) | Reduced: ratio under 0.6 in infants 2 months of age or younger; under 0.4 in patients older than 2 months. Pair with a blood glucose drawn at or near the time of the LP. |
| Protein | Normal or elevated; the normal range varies by age. |
| Lactate | Above 4 mmol/L supports bacterial meningitis, and is particularly useful in postoperative neurosurgical patients where the other parameters are harder to interpret. |
| Gram stain | Often identifies the organism, but sensitivity drops substantially if antimicrobials were given first. A negative Gram stain never justifies withholding or delaying antibiotics. |
| Culture | The diagnostic gold standard, but can be negative — especially after antimicrobials have already been started. Treat for meningitis on the strength of a positive blood culture alone even when CSF culture is negative, if the clinical picture fits. |
Molecular/PCR testing on CSF is increasingly available and particularly useful when antibiotics were given before the LP, or when Gram stain and culture are negative despite significant CSF pleocytosis — involve an infectious diseases specialist to guide further testing in this situation.
Blood investigations
Draw blood cultures (weight-based volumes) before giving antimicrobials whenever possible, but never delay antibiotics to obtain them — draw them immediately before or alongside the first antibiotic dose. Also send a CBC and differential, a blood glucose level near the time of the LP (for comparison with CSF glucose), and total blood protein.
Patients over 60 years of age, and those with underlying neurologic disease or immunosuppression, are at higher risk of Listeria monocytogenes; neuroimaging in this group may show cerebritis or other findings that support that diagnosis.
Treatment Targets
- Start empiric antibiotic therapy that penetrates the central nervous system as soon as bacterial meningitis is suspected clinically — do not wait for confirmatory testing.
- Modify therapy once a pathogen and its susceptibilities are identified.
- Eradicate the causative bacteria from the CSF.
- Decrease mortality and the risk of permanent neurologic disability.
- Identify, prevent, and manage acute complications — raised intracranial pressure, seizures, septic shock, hydrocephalus — before they cause permanent damage.
- Provide postexposure prophylaxis to close contacts, and eradicate nasopharyngeal carriage in the index patient, when the causative organism is N. meningitidis or H. influenzae type b.
Choose Initial Treatment
Time to antibiotics
Give the first dose of empiric IV antibiotics within 1 hour of when bacterial meningitis is first suspected. Antibiotics are given before, not after, diagnostic confirmation — draw blood cultures immediately and start antibiotics regardless of whether the lumbar puncture or imaging has happened yet.[2][4]
Empiric antibacterial therapy by age and risk factor
Neonates under 1 month
Covers group B streptococcus, E. coli and other Enterobacteriaceae, and (rarely) Listeria: 1st line ampicillin + cefotaxime. Add gentamicin if early-onset group B streptococcal meningitis is suspected, for synergy. If the initial CSF Gram stain shows Gram-negative bacilli, strongly consider empiric meropenem instead.
Infants and children 1 month and older, no additional risk factors
Covers S. pneumoniae, N. meningitidis, group B streptococcus, and H. influenzae: 1st line ceftriaxone or cefotaxime plus vancomycin, to cover possible penicillin/cephalosporin-resistant S. pneumoniae.[5]
Adults with no additional risk factors
Covers S. pneumoniae, N. meningitidis, and (rarely) aerobic Gram-negative bacilli: 1st line ceftriaxone or cefotaxime plus vancomycin.[6][7]
Age over 60, immunocompromised, pregnant, or alcohol use disorder
Add coverage for Listeria monocytogenes: 1st line ceftriaxone or cefotaxime plus vancomycin plus ampicillin. The same addition applies to malignancy, transplantation, humoral immune deficiency, and exposure to biologic therapy (particularly eculizumab).[6]
CSF leak, skull fracture, penetrating head trauma, recent neurosurgery, or ventriculoperitoneal shunt
Covers S. epidermidis, S. aureus, S. pneumoniae, N. meningitidis, H. influenzae, and aerobic Enterobacteriaceae: 1st line ceftriaxone or cefotaxime plus vancomycin. Soil-contaminated trauma replace the cephalosporin with ceftazidime for Pseudomonas coverage and add empiric amphotericin B for fungal coverage.
Vancomycin timing: when giving vancomycin together with a 3rd-generation cephalosporin, give the cephalosporin first and vancomycin about 2 hours later — this preserves the cephalosporin's early, broad CSF penetration.
Penicillin allergy: the cross-reactivity between ceftriaxone and penicillin/amoxicillin is negligible because their side chains differ, so a documented penicillin allergy — even an IgE-mediated one — is not, by itself, a reason to withhold ceftriaxone; take standard precautions with the first dose and discuss with the patient. Rapid penicillin desensitization is an option for a genuinely severe reaction, but must not be allowed to delay empiric therapy.[6]
Adjunctive dexamethasone: give adults dexamethasone 10 mg IV every 6 hours for 4 days, and children over 3 months dexamethasone 0.15 mg/kg IV (maximum 10 mg) every 6 hours for 4 days, starting before or with the first dose of antibiotics — dexamethasone given after antibiotics have already started loses most of its benefit.[2] If dexamethasone is delayed less than 12 hours after the first antibiotic dose, give it as soon as possible; if delayed more than 12 hours, seek infectious diseases advice on whether it is still likely to help.[2]
Dexamethasone discontinuation: stop dexamethasone if cultures do not grow H. influenzae or S. pneumoniae, and do not start it — or stop it if already started — when Listeria is suspected or confirmed; dexamethasone has not shown benefit for other pathogens and may worsen outcomes in listerial meningitis.[8]
Culture-directed therapy: narrow empiric therapy once an organism and its susceptibilities are known (see Drug Tables for the full pathogen-directed regimen and duration table). Discontinue vancomycin if cultures remain negative at 36–48 hours, or once the isolate is confirmed susceptible to penicillin or ceftriaxone/cefotaxime.
Postexposure chemoprophylaxis is a separate decision from treating the index patient, aimed at close contacts of confirmed N. meningitidis or H. influenzae type b disease. N. meningitidis, non-pregnant contacts 1 month and older rifampin (alternatives: ciprofloxacin or ceftriaxone). N. meningitidis, pregnancy ceftriaxone — rifampin and ciprofloxacin are both avoided in pregnancy. H. influenzae type b, household contacts of an unimmunized/incompletely immunized child under 4, or an immunocompromised household member rifampin. S. pneumoniae contacts do not need chemoprophylaxis. Start prophylaxis within 24 hours of identifying the index case, and give the index patient prophylaxis before discharge as well if ceftriaxone or cefotaxime was not used as their empiric therapy, since neither of the other regimens reliably eradicates nasopharyngeal carriage.[9][10]
Non-Pharmacologic Treatment
- Manage as a medical emergency in an acute care setting with immediate access to laboratory and imaging support — do not manage suspected bacterial meningitis in a primary-care or community setting.
- Continuous monitoring of airway, breathing, circulation, and neurologic status (level of consciousness, pupils, focal signs) — decompensation can be rapid, especially in meningococcemia.
- Seizure precautions, and prompt treatment of any seizure that occurs.
- Careful fluid management — avoid both under-resuscitation in septic shock and over-aggressive free-water administration, since the syndrome of inappropriate antidiuretic hormone secretion is a recognized complication that can worsen cerebral edema.
- Elevate the head of the bed and involve neurosurgery/critical care early if there are signs of raised intracranial pressure.
- Droplet precautions for the first 24 hours of effective antibiotic therapy in any patient with suspected or confirmed N. meningitidis meningitis.
- Notify public health promptly — invasive meningococcal disease and H. influenzae type b disease are reportable, and contact tracing needs to happen quickly given the short postexposure-prophylaxis window.
- Involve infectious diseases, neurology, and (when relevant) neurosurgery early, particularly for resistant organisms, complications, or lack of improvement.
- Arrange an audiology assessment before or shortly after discharge, given the real risk of sensorineural hearing loss.
Special Populations
Pregnancy
Manage suspected bacterial meningitis in pregnancy with the same urgency as in a non-pregnant patient, with combined obstetric/infectious diseases involvement. Ceftriaxone or cefotaxime plus ampicillin form a safe empiric backbone; vancomycin and gentamicin are used when indicated with the same monitoring as any pregnant patient on these agents. For postexposure prophylaxis, ceftriaxone is the drug of choice in pregnancy — rifampin and ciprofloxacin are both avoided. Dexamethasone use in pregnancy is individualized, weighing maternal benefit against the more limited safety data in this population. Intrapartum antibiotic prophylaxis (typically penicillin) for a birthing parent colonized with group B streptococcus meaningfully reduces the risk of early-onset neonatal GBS disease, including neonatal meningitis, and should be confirmed as part of the newborn's risk assessment.[5]
Breastfeeding
Ceftriaxone, cefotaxime, vancomycin, ampicillin, gentamicin, and dexamethasone are all considered compatible with breastfeeding at standard treatment doses — confirm specifics against each drug's own Drug Database entry. Rifampin and ciprofloxacin, used for prophylaxis rather than pregnancy, are generally compatible with breastfeeding even though both are avoided in pregnancy itself.
Neonates and children
Cefotaxime, not ceftriaxone, is preferred in neonates under 6 weeks given the theoretical risk of bilirubin displacement and kernicterus. All antibiotic doses in neonates and infants should follow current age/weight-banded neonatal dosing protocols, ideally with neonatology or pediatric infectious diseases involvement. Arrange developmental and audiology follow-up after recovery, since neurologic and hearing sequelae are more common — and more consequential for long-term development — in this age group.
Renal impairment
Vancomycin and the aminoglycosides (gentamicin, tobramycin) require dose adjustment and therapeutic drug monitoring in renal impairment; sulfamethoxazole/trimethoprim also requires adjustment. Confirm dosing against each drug's own product-specific renal-adjustment guidance and monitor renal function closely throughout therapy.
Immunocompromised, asplenic, and eculizumab-treated patients
Add ampicillin for Listeria coverage in this group. Prioritize catch-up meningococcal, pneumococcal, and Hib vaccination once the acute illness has resolved. Patients starting eculizumab or another terminal-complement inhibitor should receive both the quadrivalent meningococcal ACYW conjugate vaccine and a meningococcal group B vaccine series at least 2 weeks before the first eculizumab dose whenever possible, since these patients carry a markedly elevated risk of meningococcal disease even when fully vaccinated.[9] In this high-risk group, give the pneumococcal conjugate vaccine first, followed by the 23-valent pneumococcal polysaccharide vaccine at least 8 weeks later if it has not already been given.[11] Confirm Hib immunization status as well — the Hib conjugate series does not fully eliminate risk in an unvaccinated or incompletely vaccinated high-risk adult, and catch-up dosing may be appropriate on specialist advice.[12]
Older adults (over 60)
Add ampicillin for Listeria coverage. Older adults carry a higher overall risk of death and disability from bacterial meningitis and need closer monitoring for medication-related adverse effects (renal function, drug interactions, corticosteroid effects) throughout therapy.
Monitoring & Follow-Up
Perform neurologic checks (level of consciousness, pupils, focal signs) and vital signs frequently in the first 24–48 hours, then per unit protocol as the patient stabilizes. Reassess clinically at 48–72 hours — failure to improve, or new deterioration, needs repeat neuroimaging and consideration of repeat lumbar puncture.
Repeat LP is specifically indicated for: failure to improve clinically, cephalosporin-resistant pneumococcal meningitis, or meningitis caused by enteric Gram-negative bacilli or other unusual pathogens.
Monitor vancomycin trough concentrations (target 15–20 mg/L) and aminoglycoside levels closely, along with renal function, throughout therapy. Discontinue vancomycin once the isolate is confirmed penicillin- or ceftriaxone/cefotaxime-susceptible, or at 36–48 hours if cultures remain negative.
Arrange a formal audiology assessment before or shortly after discharge — sensorineural hearing loss is one of the most common permanent sequelae, particularly with S. pneumoniae and H. influenzae type b.
Before discharge, confirm the index patient has received chemoprophylaxis if ceftriaxone or cefotaxime was not used as empiric therapy, and confirm public health has been notified for contact tracing and close-contact prophylaxis for N. meningitidis and H. influenzae type b cases.
Arrange longer-term follow-up for neurologic and developmental sequelae — ataxia, behavioural changes, epilepsy, hydrocephalus, intellectual deficit, sensorineural hearing loss, and visual problems including cortical blindness can all emerge or persist after the acute illness, particularly in children, and warrant referral to neurology, audiology, and/or developmental follow-up as appropriate.
Once recovered, confirm the patient is up to date on meningococcal, pneumococcal, and (if age-appropriate) H. influenzae type b vaccination, since a first episode does not protect against future disease from other serotypes or serogroups.
Common Errors to Avoid
- Waiting for a CT scan, lumbar puncture, or confirmed diagnosis before giving antibiotics — give empiric antibiotics within 1 hour of suspicion regardless of what workup has or has not happened yet.
- Withholding antibiotics because the Gram stain is negative — a negative Gram stain does not rule out bacterial meningitis.
- Giving vancomycin before or at the same time as the cephalosporin, rather than giving the cephalosporin first and vancomycin about 2 hours later.
- Forgetting to add ampicillin for Listeria coverage in patients over 60, immunocompromised patients, pregnant patients, or those with alcohol use disorder.
- Using ceftriaxone in a neonate under 6 weeks of age — use cefotaxime instead, given the theoretical risk of bilirubin displacement and kernicterus.
- Continuing empiric vancomycin beyond 36–48 hours once cultures are negative or the isolate is confirmed penicillin/ceftriaxone-susceptible.
- Using penicillin G as empiric, rather than culture-directed, therapy — current resistance rates no longer support this for empiric use.
- Starting dexamethasone after the antibiotic course is already well underway — it needs to be given before or with the first antibiotic dose to have benefit, not added later.
- Continuing dexamethasone in a patient with confirmed or strongly suspected Listeria meningitis.
- Using imipenem instead of meropenem when a carbapenem is needed — imipenem carries a higher seizure risk in this setting.
- Missing a non-blanching petechial or purpuric rash as a marker of meningococcemia requiring an even more urgent, aggressive response.
- Discharging an index patient with N. meningitidis or H. influenzae type b meningitis without chemoprophylaxis when ceftriaxone/cefotaxime was not used empirically, or failing to notify public health for contact tracing.
Clinical Decision Algorithm
Drug Tables
How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.
IV Antibacterial Therapy — Empiric and Culture-Directed
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Ampicillin | Neonates 0-7 days: 150 mg/kg/day IV divided Q8H (200 mg/kg/day divided Q8H if GBS confirmed) Neonates 8-28 days: 200 mg/kg/day IV divided Q6H (300-400 mg/kg/day divided Q4-6H if GBS confirmed) Infants and children (1 month+): 200-400 mg/kg/day IV divided Q4-6H, maximum 12 g/day Adults: 2 g IV Q4H, maximum 12 g/day | Rash, hypersensitivity, drug fever, GI upset, seizures at high doses | Increased incidence of rash with concurrent allopurinol | Empiric backbone in all neonates, and added for Listeria coverage in at-risk groups beyond the neonatal period. |
| Cefotaxime | Neonates 0-7 days: 100-150 mg/kg/day IV divided Q8-12H Neonates 8-28 days: 150-200 mg/kg/day IV divided Q6-8H Infants and children (1 month-12 years): 225-300 mg/kg/day IV divided Q6H, maximum 12 g/day Adults and children over 12 years: 2 g IV Q4-6H, maximum 12 g/day | Hypersensitivity, phlebitis, diarrhea, transient LFT elevation, leukopenia/neutropenia, seizures/nephrotoxicity at large doses | None significant at meningitis doses | Preferred over ceftriaxone in neonates under 6 weeks of age given the theoretical bilirubin-displacement risk. |
| Ceftriaxone | Infants and children (1 month+): 100 mg/kg/day IV divided Q12H, maximum 4 g/day Adults: 2 g IV Q12H, maximum 4 g/day | Hypersensitivity, phlebitis, biliary sludging/pseudolithiasis, diarrhea, transient LFT elevation | Do not co-administer with calcium-containing IV solutions (risk of precipitation) | Contraindicated in neonates under 6 weeks — use cefotaxime instead. Give ≥2 hours before vancomycin, not simultaneously. |
| Ceftazidime | Neonates 0-7 days: 100-150 mg/kg/day IV divided Q8-12H Infants and children over 7 days: 150 mg/kg/day IV divided Q8H Adults: 2 g IV Q8H, maximum 6 g/day | Hypersensitivity, phlebitis, diarrhea, transient LFT elevation, seizures/nephrotoxicity at large doses | None significant at meningitis doses | Substitute for ceftriaxone/cefotaxime specifically when Pseudomonas coverage is needed (soil-contaminated trauma). |
| Meropenem | Neonates: 80 mg/kg/day IV divided Q12H Infants (over 4 weeks) and children: 120 mg/kg/day IV divided Q8H, maximum 6 g/day Adults: 2 g IV Q8H, maximum 6 g/day | GI upset, hypersensitivity, seizures (lower risk than imipenem) | Can decrease valproic acid levels; seizure risk increases with poor renal function | Reserve antimicrobial — use for confirmed resistance, severe penicillin allergy, or Gram-negative bacilli on initial neonatal Gram stain. Obtain infectious diseases input before use. |
| Vancomycin | Neonates: Per local neonatal dosing protocol — individualized by gestational and postnatal age, with trough monitoring Infants (over 4 weeks) and children: 60 mg/kg/day IV divided Q6H, maximum 1 g/dose or 4 g/day, adjusted to trough Adults: 15-20 mg/kg IV Q8-12H, targeting a trough of 15-20 mg/L | Vancomycin infusion reaction (flushing, hypotension with rapid infusion), phlebitis, nephrotoxicity, ototoxicity | Enhanced nephro/ototoxicity with aminoglycosides, amphotericin B, loop diuretics | Give about 2 hours after the cephalosporin dose. Discontinue by 24-48 hours if cultures are negative, or once the isolate is confirmed penicillin/ceftriaxone-susceptible. |
| Penicillin G | Older infants and children: 400,000 units/kg/day IV divided Q4H, maximum 24 million units/day Adults: 20-24 million units/day IV divided Q4H, or by continuous infusion per institutional protocol | Rash, hypersensitivity, drug fever, hemolytic anemia, interstitial nephritis, seizures at high doses | Tetracyclines may reduce penicillin effectiveness | Culture-directed therapy only, once confirmed penicillin-susceptible S. pneumoniae or N. meningitidis — not used as empiric therapy given current resistance rates. |
| Gentamicin | Neonates and infants: Per local weight/postnatal-age-banded neonatal dosing protocol, with level monitoring Adults and adolescents: 1-2 mg/kg IV/IM Q8H, adjusted to levels | Nephrotoxicity (dose/duration-dependent), ototoxicity | Enhanced toxicity with amphotericin B, vancomycin, other nephro/ototoxic agents | Used only for synergy alongside ampicillin or penicillin (GBS, Listeria, Enterobacteriaceae), for 3-7 days, never as monotherapy. Tobramycin may be substituted. |
| Tobramycin | Neonates and infants: Per local weight/postnatal-age-banded neonatal dosing protocol, with level monitoring Adults and adolescents: 1-2 mg/kg IV/IM Q8H, adjusted to levels | Nephrotoxicity (dose/duration-dependent), ototoxicity | Enhanced toxicity with amphotericin B, vancomycin, other nephro/ototoxic agents | May be substituted for gentamicin for the same synergy indications. |
| Sulfamethoxazole/Trimethoprim | Infants (2 months+), children, and adults: 10-20 mg/kg/day IV (trimethoprim component) divided Q6-12H | Nausea, vomiting, hypersensitivity (may be severe), myelosuppression, hyperkalemia at higher doses | May increase phenytoin, sulfonylurea, and warfarin effect; enhanced bone marrow suppression with methotrexate | Alternative for Listeria in a patient with severe penicillin allergy who cannot receive ampicillin. Contraindicated in neonates (kernicterus risk). Use with caution in G6PD deficiency. |
| Amphotericin B | Adults and children: Per current institutional formulary dosing — specialist-directed only | Nephrotoxicity, infusion reactions, electrolyte wasting | Increased cardiotoxicity with dexamethasone; enhanced nephrotoxicity with aminoglycosides/vancomycin | Added empirically for fungal coverage only in soil-contaminated penetrating trauma, alongside ceftazidime. Not part of routine empiric therapy. |
| Moxifloxacin | Adults: 400 mg IV/PO once daily | Tendinopathy, QT prolongation, CNS effects, GI upset | Avoid with other QT-prolonging drugs; absorption reduced by antacids/iron/calcium | Rare-resistance or true-anaphylaxis reserve option, only if the isolate is confirmed susceptible. Not standard meningitis therapy — resistance can develop quickly. Infectious diseases consultation required. |
Adjunctive Corticosteroid Therapy
Give before or with the first dose of antibiotics; giving it later loses most of the benefit.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Dexamethasone | Adults: 10 mg IV Q6H for 4 days Children over 3 months: 0.15 mg/kg IV (maximum 10 mg) Q6H for 4 days Children under 3 months: Not established for routine use — specialist-directed only | Hyperglycemia, GI upset/bleeding risk, mood changes, delayed wound healing with prolonged use | May reduce antibody response if a live-virus vaccine is given concurrently | Discontinue if cultures do not grow H. influenzae or S. pneumoniae. Do not use — or stop if already started — if Listeria is suspected or confirmed. |
Duration of Therapy by Pathogen, Once Susceptibilities Are Known
Uncomplicated bacterial meningitis in a patient responding appropriately to therapy; complications or delayed clinical response may require a longer course.
| Pathogen | 1st line | Alternative | Duration |
|---|---|---|---|
| S. pneumoniae, penicillin-susceptible | Penicillin G | Ceftriaxone or cefotaxime | 10 days |
| S. pneumoniae, penicillin-non-susceptible, cefotaxime/ceftriaxone-susceptible | Ceftriaxone or cefotaxime | Meropenem (with infectious diseases consultation) | 10 days |
| S. pneumoniae, penicillin- and cephalosporin-non-susceptible | High-dose ceftriaxone/cefotaxime + vancomycin ± rifampin | Meropenem (with infectious diseases consultation) | 14 days |
| N. meningitidis, penicillin-susceptible | Penicillin G | Ceftriaxone or cefotaxime | 7 days |
| N. meningitidis, penicillin-non-susceptible | Ceftriaxone or cefotaxime | Meropenem (with infectious diseases consultation) | 7 days |
| H. influenzae, beta-lactamase-negative | Ampicillin | Ceftriaxone or cefotaxime | 10 days |
| H. influenzae, beta-lactamase-positive | Ceftriaxone or cefotaxime | Infectious diseases consultation | 10 days |
| Group B streptococcus | Penicillin G or ampicillin, plus 5-7 days of gentamicin/tobramycin for synergy | Cefotaxime | 14-21 days |
| Listeria monocytogenes | Ampicillin, plus 3-7 days of gentamicin/tobramycin for synergy | Sulfamethoxazole/trimethoprim | 21 days or longer |
| Enterobacteriaceae | Ceftriaxone or cefotaxime (ampicillin if susceptible) ± gentamicin/tobramycin | Meropenem (with infectious diseases consultation) | 21 days |
Postexposure Chemoprophylaxis for Close Contacts
Start within 24 hours of identifying the index case.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Rifampin | H. influenzae type b exposure, 1 month+: 20 mg/kg (maximum 600 mg) PO once daily for 4 days H. influenzae type b exposure, adults: 600 mg PO once daily for 4 days N. meningitidis exposure, under 1 month: 5 mg/kg PO Q12H for 2 days N. meningitidis exposure, 1 month+: 10 mg/kg (maximum 600 mg) PO Q12H for 2 days N. meningitidis exposure, adults: 600 mg PO Q12H for 2 days | GI upset, diarrhea, flulike illness, orange discolouration of urine/tears/sweat (contact lens staining), hepatotoxicity, rare thrombocytopenia | Induces hepatic metabolism of many drugs — oral contraceptives, anticoagulants, antihyperglycemics, immunosuppressants, methadone; check a drug interaction reference before use | Avoid in pregnancy. Also give the index patient prophylaxis before discharge if ceftriaxone/cefotaxime was not used as treatment. |
| Ciprofloxacin | Children 1 month+: 20 mg/kg (maximum 500 mg) PO single dose Adults: 500 mg PO single dose | GI upset, headache, dizziness, photosensitivity, tendinopathy | Absorption reduced by antacids, iron salts, magnesium/sucralfate; increases theophylline and caffeine levels | N. meningitidis exposure only. Avoid in pregnancy. |
| Ceftriaxone | Children 1 month to under 15 years: 125 mg IM/IV single dose Children 15 years and older, and adults: 250 mg IM/IV single dose | Injection-site pain | Increased INR with warfarin; do not reconstitute with calcium-containing solutions | N. meningitidis exposure only. Drug of choice in pregnancy for prophylaxis. |
Vaccines for Prevention of Bacterial Meningitis
Public funding and eligibility vary by province/territory — confirm with the local public health authority.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Multicomponent meningococcal group B vaccine (4CMenB) | Infants 2-5 months: 0.5 mL IM at 2, 4, and 6 months, plus a booster at 12-23 months Unvaccinated 6-11 months: 3 doses (0.5 mL) at least 2 months apart, 3rd dose in the 2nd year of life Unvaccinated 12 months-17 years: 2 doses (0.5 mL) at least 2 months apart | Injection-site pain/erythema/swelling, fever (especially in infants, more frequent when co-administered with other vaccines), fatigue, headache, GI upset | Increased risk of hemolysis/low hemoglobin in patients treated with eculizumab | Infants 2-5 months: 3-dose primary series plus a booster at 12-23 months. Unvaccinated 12 months-17 years: 2-dose series. No data in infants under 2 months, or in pregnancy/breastfeeding. |
| Meningococcal group B bivalent recombinant lipoprotein vaccine (MenB-fHBP) | Standard schedule, 10 years+: 2 doses (0.5 mL) 6 months apart Increased-risk individuals (e.g., asplenia, complement deficiency): 3 doses (0.5 mL): 2nd dose at least 1 month after the 1st, 3rd dose at least 4 months after the 2nd | Injection-site pain/erythema/swelling, fatigue, fever, headache, GI upset | None significant | Alternative meningococcal group B vaccine for individuals 10 years and older. No data under age 10 or in pregnancy/breastfeeding. |
| Meningococcal group C conjugate vaccine (Men-C-C) | All eligible ages per schedule: 0.5 mL IM | Injection-site pain/erythema/swelling, headache, fever, GI upset | None significant | Given per the provincial/territorial routine immunization schedule. |
| Meningococcal groups A, C, W-135, Y conjugate vaccine (Menveo) | All eligible ages per schedule: 0.5 mL IM | Injection-site pain/erythema/swelling, headache, fever, GI upset | None significant | Given per the provincial/territorial routine immunization schedule; recommended for adolescents, high-risk groups, and before starting eculizumab. Equivalent to Nimenrix and MenQuadfi below. |
| Meningococcal groups A, C, W-135, Y conjugate vaccine (Nimenrix) | All eligible ages per schedule: 0.5 mL IM | Injection-site pain/erythema/swelling, headache, fever, GI upset | None significant | Equivalent alternative to Menveo/MenQuadfi — given per the provincial/territorial routine immunization schedule. |
| Meningococcal groups A, C, W, Y conjugate vaccine (MenQuadfi) | All eligible ages per schedule: 0.5 mL IM | Injection-site pain/erythema/swelling, headache, fever, GI upset | None significant | Equivalent alternative to Menveo/Nimenrix — given per the provincial/territorial routine immunization schedule. |
| Pneumococcal 15-valent conjugate vaccine (Vaxneuvance) | Per current NACI schedule: 0.5 mL IM, number of doses and timing depend on age and risk group | Injection-site pain/erythema/swelling, fatigue, myalgia, fever | None significant | Given per the current NACI pediatric or adult schedule for age and risk group. |
| Pneumococcal 20-valent conjugate vaccine (Prevnar 20) | Per current NACI schedule: 0.5 mL IM, number of doses and timing depend on age and risk group | Injection-site pain/erythema/swelling, fatigue, myalgia, fever | None significant | Given per the current NACI pediatric or adult schedule for age and risk group; a single-dose option in eligible adults without needing a separate PPSV23 dose. |
| Pneumococcal 21-valent conjugate vaccine (Capvaxive) | Per current NACI schedule: 0.5 mL IM, number of doses and timing depend on age and risk group | Injection-site pain/erythema/swelling, fatigue, myalgia, fever | None significant | Adult-focused conjugate vaccine given per the current NACI schedule for age and risk group. |
| Pneumococcal 23-valent polysaccharide vaccine (PPSV23) | Single dose: 0.5 mL SC/IM | Injection-site pain/erythema/swelling (more pronounced on revaccination), fatigue, myalgia, fever | Reduces immunogenicity of live zoster vaccine if co-administered — separate by at least 4 weeks | For adults 50 years and older, or high-risk individuals 2 years and older. Give at least 8 weeks after a pneumococcal conjugate vaccine if both are indicated. One-time revaccination for the highest-risk group after at least 5 years. |
| Haemophilus influenzae type b conjugate vaccine (Hib) | Per routine infant schedule: 0.5 mL IM, primary series plus booster | Injection-site pain/erythema/swelling, fever, irritability | None significant | Given per the routine infant immunization schedule. Protects only against type b — does not protect against non-b H. influenzae, including the emerging type a. |
References
- Community-acquired bacterial meningitis — The Lancet (van de Beek D, Brouwer MC, Koedel U, et al.). Lancet 2021;398(10306):1171-1183
- Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management (NG240) — National Institute for Health and Care Excellence (NICE). NICE Guideline NG240, published March 19, 2024
- Acute bacterial meningitis in adults — The Lancet (McGill F, Heyderman RS, Panagiotou S, et al.). Lancet 2016;388(10063):3036-3047
- Emergency medicine myths: computed tomography of the head prior to lumbar puncture in adults with suspected bacterial meningitis — due diligence or antiquated practice? — The Journal of Emergency Medicine (April MD, Long B, Koyfman A). J Emerg Med 2017;53(3):313-321
- Guidelines for the management of suspected and confirmed bacterial meningitis in Canadian children older than 2 months of age — Canadian Paediatric Society, Infectious Diseases and Immunization Committee (Le Saux N). Canadian Paediatric Society position statement, originally published October 19, 2020, reaffirmed January 12, 2026
- German guidelines on community-acquired acute bacterial meningitis in adults — Neurological Research and Practice (Klein M, Abdel-Hadi C, Bühler R, et al.). Neurol Res Pract 2023;5:44
- WHO guidelines on meningitis diagnosis, treatment and care — World Health Organization. Geneva: World Health Organization; 2025
- Corticosteroids for acute bacterial meningitis — Cochrane Database of Systematic Reviews (Brouwer MC, McIntyre P, Prasad K, van de Beek D). Cochrane Database Syst Rev 2015;9:CD004405
- Meningococcal vaccines: Canadian Immunization Guide — Public Health Agency of Canada, National Advisory Committee on Immunization (NACI). Canadian Immunization Guide, Part 4
- Effectiveness of antibiotics in preventing meningococcal disease after a case: systematic review — BMJ (Purcell B, Samuelsson S, Hahné SJ, et al.). BMJ 2004;328(7452):1339
- Pneumococcal vaccines: Canadian Immunization Guide — Public Health Agency of Canada, National Advisory Committee on Immunization (NACI). Canadian Immunization Guide, Part 4
- Haemophilus influenzae type b (Hib) vaccines: Canadian Immunization Guide — Public Health Agency of Canada, National Advisory Committee on Immunization (NACI). Canadian Immunization Guide, Part 4
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.