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

Diagram — Virulence enzymes: hide or spread — SeptiMap

contrast enzymes that shield the bacterium (coagulase) with those that help it spread (streptokinase), and link C. perfringens alpha-toxin to necrosis. Educational resource, not a medical device.

Diagrams: mechanisms and principles

17 sourced diagrams · for medical students and practice

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Preclinical · clinical years

Virulence enzymes: hide or spread

Objective: contrast enzymes that shield the bacterium (coagulase) with those that help it spread (streptokinase), and link C. perfringens alpha-toxin to necrosis.

Step 4 / 4
Virulence enzymes: hide or spread1. Coagulase: hiding — S. aureus coagulase activates prothrombin and converts fibrinogen to fibrin: a clot, then an abscess, that shields from phagocytosis. 2. Streptokinase: spreading — Group A streptococcal streptokinase activates plasminogen to plasmin, which degrades fibrin and tissue barriers. 3. Hyaluronidase — It cleaves hyaluronic acid; its role as a “spreading factor” is assumed, partly speculative according to the sources. 4. Alpha-toxin — C. perfringens alpha-toxin is a phospholipase C: it destroys membranes and causes the muscle necrosis of gas gangrene.HideCoagulase(S. aureus):protectivefibrin clotSpreadStreptokinase(group A strep):plasmin, fibrindegradedHyaluronidase:cleaveshyaluronic acid;spread assumedC. perfringens alpha-toxin(phospholipase C)→ muscle necrosis
  • Pathogen
  • Structure
  • Toxin, damage

Key points

  • Coagulase: fibrin walls off and protects (abscess).
  • Streptokinase: plasmin lyses fibrin and the bacterium spreads.
  • C. perfringens alpha-toxin: phospholipase C, muscle necrosis.

Classic pitfall

Writing “enzymes → spread” for all of them: coagulase does the opposite, it walls off.

Related pathogen pages (7)

Sources

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

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