Role of exotoxin A in inducing severe Pseudomonas aeruginosa infections in mice

J Med Microbiol. 1995 Sep;43(3):169-75. doi: 10.1099/00222615-43-3-169.


The effects of exotoxin A (EXA) from Pseudomonas aeruginosa on polymorphonuclear leucocytes (PMNLs) were studied in a mouse model and in vitro. P. aeruginosa PA103, which produced EXA, was 20 times more virulent for normal mice than was its EXA-deficient mutant, PA103-29. EXA was detected in the plasma of mice infected with P. aeruginosa PA103, and its presence correlated with increasing numbers of bacteria in the blood and internal organs. A monoclonal antibody (MAb) against EXA prevented the death of the mice if it was given simultaneously with, or 2 h before, infection with strain PA103. The number of PMNLs in murine blood decreased by 50% within 30 min of intravenous injection of EXA, but this decrease was prevented by simultaneous or prior injection of MAb to the toxin. EXA inhibited in-vitro phagocytosis and killing of P. aeruginosa by human and murine PMNLs and decreased the number of the PMNLs by between 60 and 68%. Collectively, these results not only confirm that EXA is toxic in vivo, but also suggest that this toxin accelerates the growth of virulent P. aeruginosa in mice.

MeSH terms

  • ADP Ribose Transferases*
  • Animals
  • Bacteremia / microbiology
  • Bacterial Toxins / biosynthesis*
  • Bacterial Toxins / immunology
  • Bacterial Toxins / toxicity
  • Disease Models, Animal
  • Exotoxins / biosynthesis*
  • Exotoxins / immunology
  • Exotoxins / toxicity
  • Lethal Dose 50
  • Leukocyte Count / drug effects
  • Lipopolysaccharides / blood
  • Male
  • Mice
  • Mice, Inbred ICR
  • Neutropenia / immunology
  • Neutropenia / microbiology
  • Neutrophils / drug effects
  • Neutrophils / immunology
  • Phagocytosis / drug effects
  • Pseudomonas Infections / microbiology*
  • Pseudomonas aeruginosa / immunology
  • Pseudomonas aeruginosa / pathogenicity*
  • Virulence
  • Virulence Factors*
  • Viscera / microbiology


  • Bacterial Toxins
  • Exotoxins
  • Lipopolysaccharides
  • Virulence Factors
  • ADP Ribose Transferases
  • Pseudomonas aeruginosa exotoxin A