Greater than 140 species of Pseudomonas have been described and most are saprophytic. In terms of human disease, Pseudomonas is generally an opportunistic pathogen. Pseudomonas infections may be serious in hospitalized patients or those with cancer or cystic fibrosis. Pseudomonads are Gram negative rods. They are motile, nonfermentative aerobes that can utilize acetate for carbon and ammonium sulphate for nitrogen.
Many species are resistent to high salt, dyes, weak antiseptics and most antibiotics.
P. aeruginosa can grow at 42 . Pseudomonas possesses the LPS endotoxin characteristic of other Gram-negative bacteria and displays O and H antigens. Pseudomonas produces many exoenzymes including hemolysins, leukocidins and proteases. In addition, a toxin called Toxin A is the most toxic product produced by Pseudomonas . The effect of this enzymatic activity is the loss of host cell protein synthesis capability.