Type III protein secretion is associated with death in lower respiratory and systemic Pseudomonas aeruginosa infections

J Infect Dis. 2001 Jun 15;183(12):1767-74. doi: 10.1086/320737. Epub 2001 May 17.


The ability of Pseudomonas aeruginosa to secrete specific toxins using the type III-mediated pathway has been reported. To determine the association of this phenotype with human illness, immunoblot analysis was used to detect expression of type III secretory proteins in P. aeruginosa isolates from respiratory tract or blood cultures of 108 consecutive patients. Relative risk of mortality was 6-fold greater with expression of the type III secretory proteins ExoS, ExoT, ExoU, or PcrV. Phenotype was independently correlated with toxicity in cellular and murine models. Prevalence of this phenotype was significantly higher in acutely infected patients than in chronically infected patients with cystic fibrosis. These results suggest that the type III protein secretion system is integral to increased P. aeruginosa virulence. A positive phenotype is a predictor of poor clinical outcome. In the future, such analyses may help distinguish potentially lethal infection from colonization and help determine appropriate therapy for critically ill patients.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acute Disease
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Bacterial Proteins / metabolism*
  • Biomarkers
  • Child
  • Child, Preschool
  • Chronic Disease
  • Cystic Fibrosis / microbiology
  • Female
  • Humans
  • Immunoblotting
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Phenotype
  • Prevalence
  • Pseudomonas Infections / microbiology
  • Pseudomonas Infections / mortality*
  • Pseudomonas aeruginosa / metabolism*
  • Pseudomonas aeruginosa / pathogenicity
  • Respiratory Tract Infections / microbiology
  • Respiratory Tract Infections / mortality*


  • Bacterial Proteins
  • Biomarkers