Bacterial Meningitis¶
VERSION: 1.1 CREATED: January 24, 2026 REVISED: January 24, 2026 STATUS: Draft - Pending Review
DIAGNOSIS: Bacterial Meningitis
ICD-10: G00.9 (Bacterial meningitis, unspecified), G00.0 (Hemophilus meningitis), G00.1 (Pneumococcal meningitis), G00.2 (Streptococcal meningitis), G00.3 (Staphylococcal meningitis), G00.8 (Other bacterial meningitis), G01 (Meningitis in bacterial diseases classified elsewhere), G03.9 (Meningitis, unspecified)
SCOPE: Evaluation and empiric treatment of acute community-acquired bacterial meningitis in adults. Covers empiric antibiotic selection by age/risk, dexamethasone adjunctive therapy, lumbar puncture interpretation, and ICU management. Excludes neonatal meningitis, healthcare-associated/post-neurosurgical meningitis, tuberculous meningitis, and fungal meningitis.
CLINICAL SYNONYMS: Acute bacterial meningitis, pyogenic meningitis, purulent meningitis, community-acquired meningitis
KEY CLINICAL FEATURES: - Classic triad: Fever, headache, neck stiffness (present in <50% of cases) - Additional features: Altered mental status (most sensitive sign), photophobia, nausea/vomiting - Physical exam: Kernig sign, Brudzinski sign (low sensitivity), petechial/purpuric rash (meningococcal) - Red flags: Rapid deterioration, seizures, focal deficits, papilledema
COMMON PATHOGENS BY AGE:
| Age/Risk | Most Common Organisms |
|---|---|
| 16-50 years | Streptococcus pneumoniae, Neisseria meningitidis |
| >50 years | S. pneumoniae, N. meningitidis, Listeria monocytogenes, aerobic GNR |
| Immunocompromised | Listeria, GNR, S. pneumoniae, fungi |
| Alcoholism | S. pneumoniae, Listeria |
| Post-neurosurgery | Staphylococci, GNR, P. aeruginosa |
| CSF shunt | S. epidermidis, S. aureus, GNR |
PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting
⚡ TIME-CRITICAL EMERGENCY
Do NOT delay antibiotics for LP or imaging. Give empiric antibiotics within 1 hour of presentation. Every hour of delay increases mortality by 12.6%.
⚠️ DEXAMETHASONE TIMING
Give dexamethasone BEFORE or WITH the first dose of antibiotics. No benefit if given >4 hours after antibiotics.
═══════════════════════════════════════════════════════════════ SECTION A: ACTION ITEMS ═══════════════════════════════════════════════════════════════
1. LABORATORY WORKUP¶
1A. Essential/Core Labs¶
| Test | Rationale | Target Finding | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|
| Blood cultures (2 sets) | Identify organism (positive in 50-80%) | Organism identification | STAT | STAT | — | STAT |
| CBC with differential | Leukocytosis, left shift; baseline | Elevated WBC; bandemia | STAT | STAT | — | STAT |
| CMP (BMP + LFTs) | Renal/hepatic function for antibiotic dosing | Normal or evidence of sepsis | STAT | STAT | — | STAT |
| Lactate | Sepsis severity marker | <2 mmol/L (elevated indicates sepsis) | STAT | STAT | — | STAT |
| Procalcitonin | Bacterial vs viral differentiation | Elevated (>0.5 ng/mL suggests bacterial) | STAT | STAT | — | STAT |
| PT/INR, PTT | Pre-LP coagulation status | INR <1.5, PTT normal | STAT | STAT | — | STAT |
| Platelet count | Pre-LP, DIC screening | >50,000/μL for safe LP | STAT | STAT | — | STAT |
| Blood glucose | Compare with CSF glucose | Document for CSF ratio | STAT | STAT | — | STAT |
| Urinalysis | Infection source if UTI | Document | STAT | ROUTINE | — | STAT |
1B. Extended Workup (Second-line)¶
| Test | Rationale | Target Finding | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|
| CRP | Inflammatory marker, follow response | Elevated; trend with treatment | URGENT | ROUTINE | — | URGENT |
| D-dimer, fibrinogen | DIC screening (meningococcal) | Normal (elevated = DIC) | URGENT | ROUTINE | — | STAT |
| Type and screen | Anticipate transfusion if DIC | Available | URGENT | ROUTINE | — | STAT |
| Cortisol (random) | Adrenal insufficiency (Waterhouse-Friderichsen) | Normal stress response | URGENT | ROUTINE | — | URGENT |
| HIV antibody/antigen | Immunocompromise screen | Document status | — | ROUTINE | — | ROUTINE |
| BNP/troponin | Cardiac involvement, septic cardiomyopathy | Normal or elevated | URGENT | ROUTINE | — | STAT |
| ABG or VBG | Respiratory status, acid-base | Normal or compensated | STAT | STAT | — | STAT |
1C. Rare/Specialized (Refractory or Atypical)¶
| Test | Rationale | Target Finding | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|
| Serum cryptococcal antigen | If immunocompromised | Negative | — | ROUTINE | — | ROUTINE |
| Histoplasma/Blastomyces antigen | Endemic area, immunocompromised | Negative | — | EXT | — | EXT |
| Quantiferon/T-SPOT | TB risk factors | Negative | — | ROUTINE | — | ROUTINE |
| Complement levels (C3, C4, CH50) | Recurrent Neisseria infection | Normal | — | EXT | — | EXT |
| Immunoglobulin levels | Recurrent infections | Normal | — | EXT | — | EXT |
2. DIAGNOSTIC IMAGING & STUDIES¶
2A. Essential/First-line¶
| Study | Timing | Target Finding | Contraindications | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|
| CT head without contrast | BEFORE LP if criteria met (see below) | Exclude mass, herniation, hydrocephalus | None in emergency | STAT | STAT | — | STAT |
| Chest X-ray | On admission | Pneumonia (source), aspiration | None | STAT | STAT | — | STAT |
CT Before LP Criteria (any ONE = get CT first):
- Immunocompromised state
- History of CNS disease (mass, stroke, infection)
- New onset seizure (within 1 week)
- Papilledema
- Altered level of consciousness
- Focal neurological deficit
If NO criteria → proceed directly to LP (do not delay for CT)
2B. Extended¶
| Study | Timing | Target Finding | Contraindications | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|
| MRI brain with contrast | If complications suspected | Abscess, ventriculitis, infarct, subdural empyema | Hemodynamic instability | — | URGENT | — | URGENT |
| CT venogram | If venous sinus thrombosis suspected | Sinus thrombosis | Contrast allergy | — | URGENT | — | URGENT |
| EEG | If seizures or altered mental status | Seizure activity, encephalopathy | None | — | URGENT | — | URGENT |
| Echocardiogram | If endocarditis suspected | Vegetation | None | — | ROUTINE | — | ROUTINE |
2C. Rare/Specialized¶
| Study | Timing | Target Finding | Contraindications | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|
| CT/MRI spine | If spinal epidural abscess suspected | Epidural collection | Hemodynamic instability | — | URGENT | — | URGENT |
LUMBAR PUNCTURE¶
Indication: ALL suspected bacterial meningitis (unless contraindicated)
Timing: STAT - Do NOT delay antibiotics for LP. If LP will be delayed (CT, coagulopathy), give empiric antibiotics first.
Volume Required: 10-15 mL minimum (for all studies)
| Study | Rationale | Target Finding | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|
| Opening pressure | Elevated in bacterial meningitis | 10-20 cmH2O normal; often >30 in bacterial | STAT | STAT | — | STAT |
| Cell count with differential (tubes 1 and 4) | Pleocytosis pattern | WBC >1000/μL typical; PMN predominant (>80%) | STAT | STAT | — | STAT |
| Protein | Elevated in bacterial infection | >100 mg/dL (often >200-500) | STAT | STAT | — | STAT |
| Glucose with serum glucose | Low in bacterial meningitis | <40 mg/dL or CSF:serum ratio <0.4 | STAT | STAT | — | STAT |
| Gram stain | Rapid organism identification | Positive in 60-90% untreated | STAT | STAT | — | STAT |
| Bacterial culture | Definitive organism identification | Positive in 70-85% untreated | STAT | STAT | — | STAT |
| BioFire FilmArray Meningitis/Encephalitis Panel | Rapid multiplex PCR (14 pathogens) | Organism identification within 1 hour | STAT | STAT | — | STAT |
| Latex agglutination (if available) | Rapid antigen detection | Organism-specific antigens | URGENT | URGENT | — | URGENT |
| HSV PCR | Exclude HSV encephalitis | Negative | STAT | STAT | — | STAT |
| Procalcitonin (CSF) | Bacterial vs aseptic | Elevated in bacterial | — | ROUTINE | — | ROUTINE |
CSF Findings Comparison:
| Parameter | Bacterial | Viral | TB/Fungal |
|---|---|---|---|
| Opening pressure | Elevated (>30 cmH2O) | Normal/mild ↑ | Elevated |
| WBC count | >1000 (often >1000-10,000) | 10-500 | 100-500 |
| Cell type | PMN predominant (>80%) | Lymphocyte predominant | Lymphocyte predominant |
| Protein | >100 mg/dL (often >200) | 50-100 mg/dL | >100 mg/dL |
| Glucose | <40 mg/dL or <0.4 ratio | Normal | Low |
| Gram stain | Positive 60-90% | Negative | Usually negative |
Special Handling: Gram stain and culture STAT. BioFire Panel STAT. Cell count within 1 hour.
Contraindications: Signs of herniation, papilledema with mass effect, severe coagulopathy (INR >1.5, platelets <50K), skin infection at LP site. Get CT first if any criteria above.
NOTE: A negative Gram stain does NOT rule out bacterial meningitis. Continue empiric antibiotics until cultures finalize.
3. TREATMENT¶
CRITICAL: Antibiotics within 1 hour. Dexamethasone before or with first antibiotic dose. Do NOT wait for LP or CT if they will delay treatment.
3A. Empiric Antibiotic Therapy¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Ceftriaxone | IV | Empiric coverage (all ages) | 2 g q12h :: IV :: q12h :: 2 g IV q12h; meningeal dosing required | Severe cephalosporin allergy | Renal function | STAT | STAT | — | STAT |
| Vancomycin | IV | DRSP coverage (all patients) | 15-20 mg/kg q8-12h; 25-30 mg/kg load :: IV :: q8-12h :: Load 25-30 mg/kg IV, then 15-20 mg/kg q8-12h (target trough 15-20 mcg/mL); adjust for renal function | Renal impairment (adjust dose) | Trough levels, renal function, ototoxicity | STAT | STAT | — | STAT |
| Ampicillin | IV | Listeria coverage (age ≥50-60, immunocompromised, alcoholism) | 2 g q4h :: IV :: q4h :: 2 g IV q4h; required for Listeria coverage in at-risk patients; NOTE: guidelines vary (≥50 vs >60) - use lower threshold if any additional risk factors | Penicillin allergy (use TMP-SMX) | Renal function | STAT | STAT | — | STAT |
| Dexamethasone | IV | Adjunctive therapy (BEFORE/WITH antibiotics) | 0.15 mg/kg q6h x 4 days :: IV :: q6h x 4 days :: 0.15 mg/kg IV (typically 10 mg) q6h x 4 days; give 15-20 min BEFORE or WITH first antibiotic dose; see immunocompromised guidance below | GI bleed (relative), see immunocompromised guidance | Glucose, GI bleeding | STAT | STAT | — | STAT |
Age-Based Empiric Regimen:
| Age/Risk | Empiric Regimen |
|---|---|
| 16-50 years (healthy) | Ceftriaxone + Vancomycin |
| ≥50 years (some guidelines use >60) | Ceftriaxone + Vancomycin + Ampicillin |
| Immunocompromised | Ceftriaxone + Vancomycin + Ampicillin |
| Alcoholism | Ceftriaxone + Vancomycin + Ampicillin |
| Severe penicillin allergy | Meropenem + Vancomycin (or chloramphenicol + TMP-SMX) |
Note: Age threshold for Listeria coverage varies between guidelines (≥50 vs >60). Use lower threshold (≥50) when additional risk factors present (diabetes, malnutrition, chronic disease).
3B. Organism-Directed Therapy (After Culture/Sensitivity)¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Penicillin G | IV | Penicillin-sensitive pneumococcus, meningococcus | 4 million units q4h :: IV :: q4h :: 4 million units IV q4h; can de-escalate if susceptible | Penicillin allergy | Renal function | — | STAT | — | STAT |
| Ceftriaxone (continued) | IV | Pneumococcus (intermediate), meningococcus, H. flu | 2 g q12h :: IV :: q12h :: Continue 2 g IV q12h if organism susceptible | Cephalosporin allergy | Renal function | — | STAT | — | STAT |
| Ampicillin (continued) | IV | Listeria monocytogenes | 2 g q4h :: IV :: q4h :: 2 g IV q4h x 21 days for Listeria | Penicillin allergy | Renal function | — | STAT | — | STAT |
| TMP-SMX | IV | Listeria (penicillin-allergic) | 5 mg/kg TMP q6h :: IV :: q6h :: 5 mg/kg (TMP component) IV q6h; alternative for Listeria | Sulfa allergy, severe renal impairment | Renal function, K+, rash | — | STAT | — | STAT |
| Meropenem | IV | Resistant GNR, penicillin allergy | 2 g q8h :: IV :: q8h :: 2 g IV q8h; meningeal dosing | Carbapenem allergy | Renal function, seizures | — | STAT | — | STAT |
3C. Treatment Duration by Organism¶
| Organism | Duration |
|---|---|
| Neisseria meningitidis | 7 days |
| Haemophilus influenzae | 7 days |
| Streptococcus pneumoniae | 10-14 days |
| Group B Streptococcus | 14-21 days |
| Listeria monocytogenes | ≥21 days |
| Gram-negative bacilli | 21 days |
| Unknown organism | 10-14 days (minimum) |
3D. Dexamethasone Guidance¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Dexamethasone (continue) | IV | Proven pneumococcal meningitis | 0.15 mg/kg q6h x 4 days :: IV :: q6h x 4 days :: Continue full 4-day course if S. pneumoniae confirmed | See below | Glucose, GI bleed | — | STAT | — | STAT |
| Dexamethasone (discontinue) | — | Non-pneumococcal meningitis | N/A :: — :: :: DISCONTINUE dexamethasone if organism other than S. pneumoniae (benefit unproven) | — | — | — | STAT | — | STAT |
Dexamethasone Notes: - Greatest benefit: Pneumococcal meningitis (reduces mortality and hearing loss) - Timing critical: Must be given BEFORE or WITH first antibiotic dose; no benefit if started >4 hours after antibiotics - Continue if: S. pneumoniae confirmed - Discontinue if: Other organism confirmed, prior antibiotics given - Caution: May reduce CSF penetration of vancomycin (controversial; continue vancomycin anyway)
Dexamethasone in Immunocompromised Patients: - HIV: Limited evidence of benefit in HIV-positive patients; meta-analyses show uncertain benefit. Use clinical judgment. - CRITICAL - Rule out cryptococcal/TB first: Dexamethasone is contraindicated in HIV-associated cryptococcal meningitis (increased mortality shown in trials). TB meningitis benefit in HIV+ patients is uncertain. - Practical approach: If HIV status unknown, give dexamethasone empirically but send cryptococcal antigen and evaluate for TB; discontinue if cryptococcal or TB confirmed. - Other immunocompromise: Benefit unproven in transplant, chemotherapy, biologics; weigh risks vs benefits.
3E. Supportive Care¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Normal saline | IV | Fluid resuscitation, maintenance | 30 mL/kg bolus; 125 mL/hr maintenance :: IV :: bolus then maintenance :: 30 mL/kg bolus for sepsis; avoid over-hydration (cerebral edema risk) | Cerebral edema (restrict fluids) | I/O, Na+, mental status | STAT | STAT | — | STAT |
| Norepinephrine | IV | Septic shock | 0.1-0.5 mcg/kg/min; 2-30 mcg/min :: IV :: infusion :: Start 2-5 mcg/min; titrate to MAP ≥65 | — | Continuous BP, lactate | — | — | — | STAT |
| Phenytoin | IV | Seizure prophylaxis (if seizures occur) | 20 mg/kg load; 100 mg q8h :: IV :: load then q8h :: 20 mg/kg IV load (max rate 50 mg/min), then 100 mg IV q8h; NOT recommended routinely for prophylaxis | Bradycardia, heart block | Cardiac monitoring during load, levels | STAT | STAT | — | STAT |
| Levetiracetam | IV | Seizure treatment/prophylaxis | 1000 mg BID; 1500 mg BID :: IV :: BID :: 1000-1500 mg IV BID; preferred for seizure prophylaxis if indicated | Severe renal impairment (adjust) | Renal function | STAT | STAT | — | STAT |
| Acetaminophen | IV/PO | Fever, headache | 650 mg q6h; 1000 mg q6h :: IV/PO :: q6h :: 650-1000 mg q6h; max 4 g/day | Severe hepatic impairment | Temperature | STAT | STAT | — | STAT |
| Mannitol | IV | Elevated ICP | 0.5-1 g/kg bolus :: IV :: PRN :: 0.5-1 g/kg IV bolus over 15-20 min; may repeat q6h PRN; target serum osm <320 | Renal failure, hypotension | Serum osm, Na+, renal function | — | STAT | — | STAT |
| Hypertonic saline (3%) | IV | Elevated ICP | 250 mL bolus :: IV :: PRN :: 250 mL (or 30 mL of 23.4%) bolus for acute herniation; target Na 145-155 | — | Na+, serum osm | — | STAT | — | STAT |
| Enoxaparin | SC | DVT prophylaxis (after stabilization) | 40 mg daily :: SC :: daily :: 40 mg SC daily; start after 48-72h if no hemorrhagic complications | Active bleeding, recent LP, coagulopathy | Platelet count | — | ROUTINE | — | ROUTINE |
| Famotidine | IV | Stress ulcer prophylaxis | 20 mg BID :: IV :: BID :: 20 mg IV BID if on steroids or intubated | None significant | GI bleeding | — | ROUTINE | — | ROUTINE |
3F. Chemoprophylaxis for Close Contacts¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Rifampin | PO | Meningococcal prophylaxis | 600 mg BID x 2 days :: PO :: BID x 2 days :: 600 mg PO q12h x 4 doses (2 days); for household/close contacts | Pregnancy, liver disease | Orange secretions warning | — | ROUTINE | — | — |
| Ciprofloxacin | PO | Meningococcal prophylaxis | 500 mg single dose :: PO :: once :: 500 mg PO x 1 dose; alternative to rifampin | Pregnancy, children (relative) | Tendon warning | — | ROUTINE | — | — |
| Ceftriaxone | IM | Meningococcal prophylaxis | 250 mg single dose :: IM :: once :: 250 mg IM x 1 dose; safe in pregnancy | Cephalosporin allergy | None | — | ROUTINE | — | — |
| Rifampin (H. flu) | PO | H. influenzae prophylaxis | 20 mg/kg daily x 4 days :: PO :: daily x 4 days :: 20 mg/kg (max 600 mg) PO daily x 4 days; for household contacts if unvaccinated child <4 yo present | Pregnancy, liver disease | Orange secretions warning | — | ROUTINE | — | — |
Contact Prophylaxis Indications: - Meningococcal: Household contacts, daycare contacts, anyone exposed to respiratory secretions (kissing, mouth-to-mouth, intubation without mask) - H. influenzae type b: Household contacts if unvaccinated child <4 years present - Pneumococcal: No prophylaxis indicated
4. OTHER RECOMMENDATIONS¶
4A. Referrals & Consults¶
| Recommendation | ED | HOSP | OPD | ICU |
|---|---|---|---|---|
| Infectious disease consult for antibiotic optimization, duration guidance, and organism-specific management | URGENT | STAT | — | STAT |
| Neurology consult for seizure management, focal deficits evaluation, and neurological complication monitoring | URGENT | URGENT | — | STAT |
| Critical care consult for ICU admission given septic shock, hemodynamic instability, or respiratory failure | STAT | STAT | — | STAT |
| Neurosurgery consult for hydrocephalus management, abscess drainage, or elevated ICP requiring intervention | — | URGENT | — | STAT |
| ENT consult for hearing evaluation as sensorineural hearing loss is a common complication of bacterial meningitis | — | ROUTINE | — | ROUTINE |
| Audiology for formal hearing test before discharge to document baseline and detect early hearing loss | — | ROUTINE | — | ROUTINE |
| Infection control for droplet isolation implementation and contact tracing if meningococcal disease confirmed | STAT | STAT | — | STAT |
| Public health notification required for meningococcal disease (reportable condition) to enable contact prophylaxis | STAT | STAT | — | STAT |
4B. Patient Instructions¶
| Recommendation | ED | HOSP | OPD |
|---|---|---|---|
| Return immediately if worsening headache, fever, confusion, or seizures develop (may indicate treatment failure or complication) | STAT | — | STAT |
| Complete full antibiotic course even if feeling better to prevent relapse and resistance | — | STAT | STAT |
| Obtain hearing test after recovery as sensorineural hearing loss is a common complication of bacterial meningitis | — | ROUTINE | ROUTINE |
| Ensure close contacts receive prophylaxis if meningococcal disease confirmed (rifampin, ciprofloxacin, or ceftriaxone) | STAT | STAT | — |
| Report persistent headaches, hearing changes, or cognitive difficulties as these may indicate late complications | — | ROUTINE | ROUTINE |
4C. Lifestyle & Prevention¶
| Recommendation | ED | HOSP | OPD |
|---|---|---|---|
| Maintain droplet isolation (meningococcal) until 24h of effective antibiotics to prevent transmission | STAT | STAT | — |
| Meningococcal vaccination for close contacts and patient after recovery to prevent future infection | — | ROUTINE | ROUTINE |
| Pneumococcal vaccination if not up to date as pneumococcus is the most common cause of bacterial meningitis | — | ROUTINE | ROUTINE |
| Practice hand hygiene and respiratory etiquette to prevent transmission of respiratory pathogens | — | ROUTINE | ROUTINE |
| Avoid sharing utensils, drinks, or close contact with respiratory secretions during active infection | STAT | STAT | — |
═══════════════════════════════════════════════════════════════ SECTION B: REFERENCE (Expand as Needed) ═══════════════════════════════════════════════════════════════
5. DIFFERENTIAL DIAGNOSIS¶
| Alternative Diagnosis | Key Distinguishing Features | Tests to Differentiate |
|---|---|---|
| Viral meningitis | Milder course, lymphocytic CSF, normal glucose | CSF profile, viral PCR |
| HSV encephalitis | Altered mental status, temporal lobe findings, seizures | MRI brain, CSF HSV PCR |
| Tuberculous meningitis | Subacute course, basilar enhancement, low glucose | CSF AFB, adenosine deaminase, PCR |
| Fungal meningitis | Immunocompromised, indolent course | CSF fungal culture, cryptococcal antigen |
| Subarachnoid hemorrhage | Thunderclap headache, xanthochromia | CT head, LP (xanthochromia, RBCs) |
| Brain abscess | Focal deficits, ring-enhancing lesion | MRI brain with contrast |
| Subdural empyema | Post-sinusitis/otitis, focal deficits | MRI brain with contrast |
| Autoimmune encephalitis | Subacute, psychiatric symptoms, movement disorder | Autoimmune panel (serum/CSF) |
| Carcinomatous meningitis | Cancer history, cranial neuropathies | CSF cytology, MRI |
| Drug-induced meningitis | NSAIDs, IVIG, TMP-SMX exposure | Temporal relationship, improvement off drug |
| Endocarditis with CNS embolization | Heart murmur, embolic phenomena | Echocardiogram, blood cultures |
| Septic dural sinus thrombosis | Headache, papilledema, focal signs | CT/MR venography |
6. MONITORING PARAMETERS¶
| Parameter | Frequency | Target/Threshold | Action if Abnormal | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|
| Neurological exam (GCS) | q1-2h initially, then q4h | GCS stable or improving | Head CT, consider ICP monitoring | STAT | STAT | — | STAT |
| Temperature | q4h | Afebrile by 48-72h | Reassess antibiotic coverage | STAT | STAT | — | STAT |
| Blood pressure | q1-4h | MAP ≥65 | Vasopressors if septic shock | STAT | STAT | — | STAT |
| Heart rate | Continuous | 60-100 bpm | Evaluate for sepsis, arrhythmia | STAT | STAT | — | STAT |
| Oxygen saturation | Continuous | >94% | Supplement O2, consider intubation | STAT | STAT | — | STAT |
| Urine output | q4h | >0.5 mL/kg/hr | Fluid resuscitation | — | STAT | — | STAT |
| Serum sodium | q6-12h | 135-145 mEq/L | Evaluate for SIADH, cerebral salt wasting | STAT | STAT | — | STAT |
| Lactate | q6-12h until normal | <2 mmol/L | Optimize resuscitation | STAT | STAT | — | STAT |
| Vancomycin trough | Before 4th dose | 15-20 mcg/mL | Dose adjustment | — | STAT | — | STAT |
| Renal function | Daily | Cr stable | Adjust antibiotic doses | STAT | STAT | — | STAT |
| Glucose | q6h if on steroids | <180 mg/dL | Insulin | — | ROUTINE | — | STAT |
| Hearing assessment | Before discharge | Normal | Audiology referral | — | ROUTINE | — | ROUTINE |
7. DISPOSITION CRITERIA¶
| Disposition | Criteria |
|---|---|
| ICU admission | GCS <12; hemodynamic instability (septic shock); respiratory failure; seizures; signs of elevated ICP; DIC; rapidly worsening |
| Step-down/telemetry | Stable but requiring close monitoring; improving mental status; weaning vasopressors |
| General floor | Stable; GCS 15; hemodynamically stable; no seizures; improving on antibiotics |
| Discharge home | NOT recommended for acute bacterial meningitis; requires IV antibiotics |
| Transfer to higher level | Need for neurosurgical intervention; refractory elevated ICP; ECMO candidacy |
Typical Hospital Course: 10-21 days depending on organism
8. EVIDENCE & REFERENCES¶
| Recommendation | Evidence Level | Source |
|---|---|---|
| Dexamethasone before antibiotics improves outcomes in pneumococcal meningitis | Class I, Level A | de Gans et al. NEJM 2002 |
| Antibiotics within 1 hour reduce mortality | Class II, Level B | Proulx et al. QJM 2005 |
| CT before LP only if criteria met | Class II, Level B | Hasbun et al. NEJM 2001 |
| Vancomycin + ceftriaxone empiric for DRSP | Class II, Level B | Tunkel et al. IDSA Guidelines Clin Infect Dis 2004 |
| Ampicillin for Listeria coverage in at-risk | Class II, Level B | IDSA Guidelines 2004 |
| BioFire Panel for rapid diagnosis | Class II, Level B | Leber et al. J Clin Microbiol 2016 |
| Rifampin or ciprofloxacin prophylaxis for meningococcal contacts | Class I, Level A | CDC MMWR Recommendations |
| Antibiotic duration by organism | Class II, Level B | Tunkel et al. IDSA Guidelines |
| Delay in antibiotics increases mortality | Class II, Level B | Auburtin et al. Crit Care Med 2006 |
CHANGE LOG¶
v1.1 (January 24, 2026) - Citation verification: Corrected de Gans PMID (12432041)
v1.0 (January 24, 2026) - Initial template creation - Age-based empiric antibiotic selection - Dexamethasone timing guidance - CSF interpretation table - Contact prophylaxis protocols - Treatment duration by organism
APPENDIX A: CT Before LP Decision Algorithm¶
Suspected Bacterial Meningitis
│
▼
Any of the following?
• Immunocompromised
• History of CNS disease
• New onset seizure (<1 week)
• Papilledema
• Altered consciousness (GCS <14)
• Focal neurological deficit
│
┌────┴────┐
│ │
YES NO
│ │
▼ ▼
CT Head Proceed directly
STAT to LP
│ │
▼ │
No mass/ ─┘
herniation?
│
YES
│
▼
Proceed to LP
**CRITICAL: Do NOT delay antibiotics for CT or LP**
Give empiric antibiotics + dexamethasone immediately if meningitis suspected
APPENDIX B: Empiric Antibiotic Quick Reference¶
| Patient Type | Regimen | Key Points |
|---|---|---|
| 16-50 yo, healthy | Ceftriaxone 2g q12h + Vancomycin | No Listeria coverage needed |
| >50 yo | Ceftriaxone 2g q12h + Vancomycin + Ampicillin 2g q4h | Add Listeria coverage |
| Immunocompromised | Ceftriaxone 2g q12h + Vancomycin + Ampicillin 2g q4h | Broader coverage |
| Alcoholism | Ceftriaxone 2g q12h + Vancomycin + Ampicillin 2g q4h | High Listeria risk |
| Severe PCN allergy | Meropenem 2g q8h + Vancomycin | Or chloramphenicol + TMP-SMX |
| Post-neurosurgery | Vancomycin + Cefepime 2g q8h (or Meropenem) | Cover Staph, Pseudomonas |
ALL patients also receive: - Dexamethasone 0.15 mg/kg (or 10 mg) IV q6h x 4 days - Give dexamethasone 15-20 min BEFORE or WITH first antibiotic dose
APPENDIX C: CSF Parameters Quick Reference¶
| Parameter | Normal | Bacterial | Viral | TB/Fungal |
|---|---|---|---|---|
| Opening pressure | 10-20 cmH2O | >30 cmH2O | Normal/↑ | ↑↑ |
| WBC | <5/μL | 1,000-10,000 | 10-500 | 100-500 |
| Differential | — | >80% PMNs | Lymphs | Lymphs |
| Protein | 15-45 mg/dL | >200 mg/dL | 50-100 | >100 |
| Glucose | 45-80 mg/dL | <40 | Normal | <40 |
| CSF:Serum glucose | >0.6 | <0.4 | >0.6 | <0.4 |
| Gram stain | Negative | + in 60-90% | Negative | Usually - |
| Lactate | <3.5 mmol/L | >4 mmol/L | <3.5 | Variable |