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

Diagram — Intracellular life: two strategies — SeptiMap

tell apart bacteria that survive inside a vacuole from those that escape into the cytosol, and state what controls them. 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

Intracellular life: two strategies

Objective: tell apart bacteria that survive inside a vacuole from those that escape into the cytosol, and state what controls them.

Step 4 / 4
Intracellular life: two strategies1. Staying in the vacuole — M. tuberculosis prevents phagosome maturation and acidification; Salmonella and Legionella build a remodelled vacuole. 2. Leaving the vacuole — Listeria lyses the vacuole with listeriolysin O (and phospholipases); Shigella and Rickettsia also reach the cytosol. 3. Cell to cell — Listeria polymerises host actin (ActA protein) and moves into the neighbouring cell without returning to the extracellular space. 4. Control — Control relies on cell-mediated immunity: macrophages and IFN-γ-producing CD4+ and CD8+ T cells (shown for M. tuberculosis).Staying in the vacuoleMaturation andacidificationblockedM. tuberculosis, Salmonella, LegionellaEscaping to the cytosolListeriolysin OActin (ActA)Listeria, Shigella, RickettsiaControl: cell-mediated immunity(macrophages, IFN-γ-producing T cells)
  • Pathogen
  • Host (cells, tissues)
  • Toxin, damage
  • Immunity

Key points

  • Two strategies: stay in a remodelled vacuole, or escape into the cytosol.
  • Listeria: listeriolysin O to escape, actin (ActA) to move to the next cell.
  • Control relies on cell-mediated immunity.

Classic pitfall

Assuming a phagocytosed bacterium is necessarily destroyed: M. tuberculosis survives in the phagosome by blocking its maturation.

Related pathogen pages (10)

Sources

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

This page is the text version, generated at build time. The 3D anatomical atlas requires JavaScript.