Key Points
- Use the highest‑yield diagnostic test early; do not let testing delay time‑critical therapy.
- Set objective targets and reassess frequently.
- Plan definitive source control or disease‑specific therapy when indicated; document follow‑up and patient education.
Algorithm
- Recognize clinical triad ± petechiae; draw blood cultures; start IV antibiotics immediately.
- Give dexamethasone before/with first dose if pneumococcus suspected.
- Perform LP unless CT criteria present; if criteria present → CT then LP.
- Tailor antibiotics to CSF Gram stain/culture/PCR; maintain isolation for meningococcus.
- Arrange public health prophylaxis for contacts; monitor for complications (seizures, SIADH).
Clinical Synopsis & Reasoning
Suspect with fever, neck stiffness, and altered mental status. Give empiric antibiotics immediately after blood cultures; add dexamethasone before or with first dose for suspected pneumococcal meningitis. CT before LP only if focal deficit, papilledema, new seizure, immunocompromise, or altered consciousness.
Treatment Strategy & Disposition
Stabilize ABCs. Initiate guideline‑concordant first‑line therapy with precise dosing and continuous monitoring. Escalate to advanced/procedural interventions based on explicit failure criteria. Define ICU, step‑down, and ward disposition triggers; involve specialty teams early.
Epidemiology / Risk Factors
- Risk varies by comorbidity and precipitants; see citations for condition‑specific data.
Investigations
| Test | Role / Rationale | Typical Findings | Notes |
|---|
| Blood cultures ×2 then LP (unless CT criteria) | Diagnosis | CSF bacterial profile | Do not delay antibiotics |
| Head CT (only with red flags) | Safety | Mass effect/ICP | Avoid routine delay |
| CSF PCR and multiplex testing | Etiology | Pathogen ID and resistance markers | Direct therapy |
High-Risk & Disposition Triggers
| Trigger | Why it matters | Action |
|---|
| Sepsis or rapidly progressive neurologic deficits | High mortality | Immediate antibiotics + dexamethasone; ICU |
| Immunocompromise, age >50, pregnancy | Listeria risk | Add ampicillin; admit |
| Papilledema/new seizure/focal deficit | Herniation risk with LP | CT before LP; do not delay antibiotics |
| Close contacts at risk (N. meningitidis) | Public health concern | Initiate chemoprophylaxis for contacts |
| Delayed presentation >24 h | Worse outcomes | Escalate monitoring; infectious disease consult |
Pharmacology
| Medication/Intervention | Mechanism | Onset | Role in Therapy | Limitations |
|---|
| Ceftriaxone 2 g IV q12h + Vancomycin (trough-guided) | Empiric coverage | Hours | S. pneumoniae, N. meningitidis | Add Ampicillin 2 g IV q4h if >50/immunocompromised (Listeria) |
| Dexamethasone 10 mg IV q6h × 4 days | Anti-inflammatory | Hours | Improves outcomes in pneumococcal meningitis | Give before/with first antibiotics |
| Rifampin (contacts for N. meningitidis) | Chemoprophylaxis | Hours | Public health control | Alternative: ciprofloxacin, ceftriaxone |
Prognosis / Complications
- Outcome depends on timeliness of diagnosis and definitive therapy; monitor for complications.
Patient Education / Counseling
- Provide red‑flag education, adherence guidance, and explicit return precautions; arrange timely specialty follow‑up.
References
- IDSA Guidelines for Bacterial Meningitis (Adults) — Link