Educational resource · Not a medical device · Infectious diseases review in progress · Does not replace clinical judgement

Diagram — Bacterial meningitis — SeptiMap

follow pneumococcus from nasopharynx to CSF, understand why inflammation causes the damage, and explain the role of dexamethasone without prescribing it. Educational resource, not a medical device.

Diagrams: mechanisms and principles

17 sourced diagrams · for medical students and practice

Each diagram reads step by step: an objective, the steps, three key points, a classic pitfall, its sources and the related atlas pages. Revision mode hides the labels to test yourself.

Clinical years · OSCE

Bacterial meningitis

Objective: follow pneumococcus from nasopharynx to CSF, understand why inflammation causes the damage, and explain the role of dexamethasone without prescribing it.

Step 5 / 5
Bacterial meningitis1. Colonisation, invasion — For pneumococcus: nasopharyngeal colonisation, epithelial adhesion, then entry into the bloodstream. 2. Crossing the barrier — Beyond the blood–brain barrier, bacteria multiply freely: normal CSF holds very little complement. 3. Lysis and inflammation — Bacterial lysis, including lysis caused by a bactericidal antibiotic, releases components that amplify inflammation. 4. Damage — Inflammation causes cerebral oedema, hydrocephalus, cochlear damage and cerebrovascular complications. 5. Dexamethasone: the principle — It dampens the subarachnoid inflammatory response. Lower mortality is shown only for pneumococcal meningitis, not for meningitis overall. Management belongs to the guidelines.Nasopharynx: colonisation,epithelial adhesionBlood: bacteraemiaBlood–brain barrierCSF: very little complement,free multiplicationBacterial lysis (including byantibiotics) → inflammationCerebral oedema, hydrocephalus,cerebrovascular complicationsDexamethasone: dampenssubarachnoid inflammation;fewer deaths mainly with pneumococcus
  • Host (cells, tissues)
  • Pathogen
  • Toxin, damage
  • Structure
  • Clinical consequence
  • Antibiotic

Key points

  • Pneumococcus: nasopharyngeal colonisation, bacteraemia, then crossing the barrier.
  • CSF has very little complement: bacteria multiply freely.
  • Inflammation, amplified by lysis, causes the damage.

Classic pitfall

Assuming dexamethasone lowers mortality in all bacterial meningitis: a mortality reduction is shown only for pneumococcus (the SPILF guideline indications are broader).

Related pathogen pages (5)

Sources

Educational content · Illustrative mechanisms · Not applicable to individual clinical decisions · MDR 2017/745

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