VIOLIN: Vaccine Investigation and Online Information Network

Pathogen Page

Pseudomonas aeruginosa

I. General Information

1. NCBI Taxonomy ID:

2. Disease:

Pseudomonas aeruginosa infection

3. Introduction

Pseudomonas aeruginosa is member of the Gamma Proteobacteria class of Bacteria. It is a Gram-negative, aerobic rod belonging to the bacterial family Pseudomonadaceae. Since the revisionist taxonomy based on conserved macromolecules (e.g. 16S ribosomal RNA) the family includes only members of the genus Pseudomonas which are cleaved into eight groups. Pseudomonas aeruginosa is the type species of its group. which contains 12 other members. Pseudomonas aeruginosa is an opportunistic pathogen, meaning that it exploits some break in the host defenses to initiate an infection. In fact, Pseudomonas aeruginosa is the epitome of an opportunistic pathogen of humans. The bacterium almost never infects uncompromised tissues, yet there is hardly any tissue that it cannot infect if the tissue defenses are compromised in some manner. It causes urinary tract infections, respiratory system infections, dermatitis, soft tissue infections, bacteremia, bone and joint infections, gastrointestinal infections and a variety of systemic infections, particularly in patients with severe burns and in cancer and AIDS patients who are immunosuppressed. Pseudomonas aeruginosa infection is a serious problem in patients hospitalized with cancer, cystic fibrosis, and burns. The case fatality rate in these patients is near 50 percent (Textbook of Bacteriology).

4. Microbial Pathogenesis

P. aeruginosa infections are widely varied. The bacteria can colonize wounds and enter the blood stream, they can colonize the lungs, and they can also colonize the a scratched cornea. P. aeruginosa has a variety of virulence factors that contribute to its widely varied pathogenesis (Salyers and Whitt., 2002).

5. Host Ranges and Animal Models

Pseudomonas aeruginosa is an opportunistic human pathogen. The burned mouse model is used to model pseudomonas infection in burn patients. For lung infections guinea pig and rat models are used. C. elegans is also a model used to study host-pathogen interactions (Salyers and Whitt., 2002).

6. Host Protective Immunity

Most strains of P. aeruginosaare resistant to killing in serum alone, but the addition of polymorphonuclear leukocytes results in bacterial killing. Killing is most efficient in the presence of type-specific opsonizing antibodies, directed primarily at the antigenic determinants of LPS. This suggests that phagocytosis is an important defense and that opsonizing antibody is the principal functional antibody in protecting from P. aeruginosa infections. Once P. aeruginosa infection is established, other antibodies, such as antitoxin, may be important in controlling disease. Cell-mediated immunity does not seem to play a major role in resistance or defense against Pseudomonas infections (Textbook of Bacteriology).

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