pseudomonas aeruginosa: a review of their pathogenesis and prevalence in clinical settings and the environment

the genus pseudomonas consists of more than 120 species that are ubiquitous in moist environments such as water and soil ecosystems and are pathogenic to animals and humans. within the genus of pseudomonas, p. aeruginosa is most frequently associated with human infections. the bacterium is regarded as an opportunistic pathogen, primarily causing nosocomial infections in immunocompromised patients. the existing knowledge regarding the pathogenesis of p. aeruginosa has mainly been obtained through studying clinical isolates; particularly those involved in causing chronic lung infection in cystic fibrosis patients. nosocomial infections commonly associated with p. aeruginosa include ventilator-associated pneumonia, catheter-associated urinary tract infections, wound infections in severe burn patients and septicaemia with their pathogenesis shown to be multifactorial. the bacterium is also capable of producing a number of toxins via the type iii secretion system, as well as secreting enzymes and proteins including elastase, phospholipase c and siderophores. however, p. aeruginosa is also a waterborne pathogen, commonly found in environmental waters as well as in other sources such as sewage treatment plants. the public health implication of these bacteria whilst in the environment has not been fully investigated. here we review our present knowledge about the pathogenesis of p. aeruginosa in clinical settings and the environment.