II. Pathophysiology

  1. Pseudomonas Aeruginosa (previously P. Pyocyaneus)
    1. Aerobic, Gram Negative Rods
    2. Motile, non spore forming, non-lactose producing Bacteria
    3. Alginate polymer capsule shields P. aeruginosa from Phagocytosis by immune cells (e.g. Macrophages)
  2. Produces a fluorescent green pigment (pyorubin or pyoverdin) and a blue pigment (pyocyanin)
    1. Fluorescein stain used in Corneal Abrasion detection is derived from pyorubin
    2. Lends infected wounds a blue-green discharge and a sweet grape-like scent
    3. Blue-Green bandage discoloration first described by French pharmacist Carle Gessard in 1882
    4. Species name aeruginosa is derived from the latin word aerugo ("rusted Copper")
  3. Previously thought to be an obligate aerobe, but can survive also in anaerobic conditions
  4. Found in soil and water and has minimal nutrient requirements
    1. Grows in warm moist environments (esp. in contact with plastic or Rubber)
  5. Among skin flora in healthy patients
    1. However, P. Aeruginosa has weak invasive potential in the immunocompetent (without open wounds)
  6. Opportunistic, life threatening, multi-drug resistant infections in high risk patients
    1. Cystic Fibrosis
    2. Burn Injury
    3. Wound Infections
    4. Immunocompromised (e.g. Diabetes Mellitus)
    5. Nosocomial Infection
  7. Exotoxin A (PE)
    1. Inhibits Protein synthesis in cells (similar to Diphtheria toxin)
    2. Enters cells via receptor-mediated endocytosis
    3. Cellular protease breaks extotoxin A into 2 fragments
      1. Binding Protein (28 kDa fragment)
      2. Active Protein (37 kDA fragment)
        1. ADP-ribosylates elongation factor 2 (EF2) in conjunction with NAD+
        2. Halts peptide elongation
  8. Antibiotic Resistance Mechanisms
    1. Permeability mutations
      1. Outer membrane porin loss
      2. Efflux pumps
    2. Beta Lactamase
      1. Primarily AmpC production
    3. Gyrase Mutations
      1. Fluoroquinolone resistance

IV. Management: Antipseudomonal Antibiotics

  1. Intravenous Empiric Pseudomonas Coverage (before culture and sensitivity available)
    1. Piperacillin-Tazobactam (Zosyn)
    2. Ceftazidime (Fortaz)
    3. Cefepime
    4. Meropenem
    5. Ceftolozane-Tazobactam
  2. Intravenous Empiric Antibiotics for Severe beta-lactam allergy (e.g. Anaphylaxis)
    1. Aztreonam
    2. Ciprofloxacin
    3. Levofloxacin
  3. Oral Antibiotics with Antipseudomonal Activity
    1. Ciprofloxacin
    2. Levofloxacin

V. References

  1. (2025) Sanford Guide, accessed 2/1/2025
  2. Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 92-3
  3. Diggle (2020) Microbiology 166(1):30-3 +PMID: 31597590 [PubMed]
  4. Qin (2022) Signal Transduct Target Ther 7(1):199 +PMID: 35752612 [PubMed]

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Ontology: Pseudomonas aeruginosa (C0033809)

Definition (NCI) A species of facultatively anaerobic, Gram negative, rod shaped bacteria in the phylum Proteobacteria. This species is motile, non spore forming, produces pyorubin, pyocyanin and fluorescein and has minimal nutrient requirements. P. aeruginosa is an opportunistic pathogen found in soil, water and as a part of skin flora that can cause lethal infections in cystic fibrosis patients, burn victims and immunocompromised individuals.
Definition (NCI_CDISC) Any bacterial organism that can be assigned to the species Pseudomonas aeruginosa.
Definition (MSH) A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. aeruginosa is a major agent of nosocomial infection.
Definition (CSP) species of gram negative, aerobic, rod shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections); also found widely distributed in soil and water; a major agent of nosocomial infection.
Concepts Bacterium (T007)
MSH D011550
SnomedCT 52499004
English Micrococcus pyocyaneus, Pseudomonas pyocyanea, P. aeruginosa, aeruginosa pseudomonas, pseudomona aeruginosa, pyo, pseudomonas aeruginosa organism, p. aeruginosa, aeruginosa p, p aeruginosa, Pseudomonas aeruginosa (Schroeter 1872) Migula 1900, pseudomonas aeruginosa, PSEUDOMONAS AERUGINOSA, Pseudomonas aeruginosa, Bacillus aeruginosus, Bacillus pyocyaneus, Bacterium aeruginosum, Bacterium pyocyaneum, Pseudomonas polycolor, Pseudomonas pyocyaneus, Pyo, Pseudomonas aeruginosa (organism)
French Pseudomonas pyocyanea, Pseudomonas aeruginosa
Swedish Pseudomonas aeruginosa
Czech Pseudomonas aeruginosa, Bacterium pyocyaneum
Finnish Pseudomonas aeruginosa
Italian Pseudomonas pyocyanea, Pseudomonas aeruginosa
Japanese シュードモナス・エルジノーサ, 緑膿菌, シュードモナスアエルギノーザ
Croatian PSEUDOMONAS AERUGINOSA
Polish Pałeczki ropy błękitnej, Pseudomonas aeruginosa
Norwegian Pseudomonas aeruginosa, Pseudomonas pyocyanea
Spanish Pseudomonas aeruginosa (organismo), Pseudomonas aeruginosa, Pseudomonas pyocyanea
German Pseudomonas aeruginosa, Pseudomonas pyocyanea
Russian PSEUDOMONAS AERUGINOSA, PSEUDOMONAS PYOCYANEA
Dutch Pseudomonas aeruginosa, Pseudomonas pyocyanea
Portuguese Pseudomonas aeruginosa, Pseudomonas pyocyanea