Pseudomonas aeruginosa: Overview

Bacteria - Gram Negative
  1. Neisseria spp: Overview
  2. Neisseria gonorrhoeae
  3. Neisseria meningitidis
  4. Haemophilus influenzae
  5. Bordetella pertussis
  6. Brucella
  7. Legionella pneumophila
  8. Pseudomonas aeruginosa: Overview
  9. Pseudomonas aeruginosa: Disease
  10. Salmonella Overview
  11. Salmonella typhi
  12. Salmonella enteritidis
  13. Shigella
  14. Yersinia enterocolitica
  15. Escherichia coli: Overview
  16. Enterohemorrhagic E. Coli (EHEC)
  17. Enterotoxigenic E. Coli (ETEC)
  18. Klebsiella pneumoniae
  19. Campylobacter jejuni
  20. Vibrio spp.
  21. Helicobacter pylori
  22. Borrelia burgdorferi (Lyme Disease)
  23. Leptospira interrogans
  24. Treponema pallidum: Overview
  25. Treponema pallidum: Diagnosis
  26. Congenital syphilis
  27. Chlamydia: Overview
  28. Chlamydia trachomatis
  29. Chlamydia pneumoniae vs. psittaci
  30. Rickettsia rickettsii
  31. Rickettsia typhi vs. prowazekii
  32. Anaplasma vs. Ehrlichia
  33. Coxiella burnetii (Q fever)


Pseudomonas aeruginosa are gram-negative, rod-shaped, and encapsulated bacteria, with colonies that have a grape-like odor. Pseudomonas is also catalase and oxidase positive. Virulence factors of this bacteria include its production of Exotoxin A, which inhibits elongation factor 2 via ADP ribosylation. Another virulence factor produced by Pseudomonas aeruginosa are pyoverdine and pyocyanin, blue-green pigments that help the bacteria scavenge iron from its local environment.

Key Points

  • Pseudomonas aeruginosa overview 
    • Characteristics
      • Gram negative rod
        • Have a motile appearance on microscopy
      • Oxidase +
      • Encapsulated
        • Higher risk of severe infection in asplenic patients (prior surgery, sickle cell)
      • Catalase +
      • Non-lactose fermenting
      • Has a grape-like odor
      • Aerobic
      • Biofilm formation may contribute to pneumonia in cystic fibrosis
    • Virulence Factors
      • Exotoxin A
        • inactivates EF-2 (elongation factor) via ADP ribosylation
        • inhibits protein synthesis at the ribosome, since EF-2 is needed to translocate tRNA to allow peptide elongation
        • Similar mechanism to diphtheria toxin (Corynebacterium diphtheriae)
      • Pyoverdine and pyocyanin
        • blue-green pigment often seen on microscopy
        • Generates reactive oxygen species
      • Phospholipase C
        • Breaks down phospholipids to degrade cell membranes
      • Endotoxin
        • Causes fever, shock, and DIC in patients
        • Seen in all gram-negative bacteria due to LPS in the bacterial membrane
      • Elastase
        • Breaks down elastin
        • Important for blood vessel and connective tissue destruction (e.g. ecthyma gangrenosum)