Pseudomonas
Scientific classification
Kingdom: Bacteria Phylum: Proteobacteria Class: Gamma Proteobacteria Order: Pseudomonadales Family: Pseudomonadaceae Genus: Pseudomonas
Species
P. aeruginosa P. fluorescens P. fragi P. putida P. syringae etc.

The bacterial genus Pseudomonas includes plant pathogenic bacteria such as P. syringae (various pathovars), the human pathogen P. aeruginosa, the ubiquitous soil bacterium P. putida, and some species that are known to cause problems in dairy products. However, the actions of this group of bacteria are mainly considered as beneficial or neutral to man. In recent times, members of the Pseudomonas have been used as biocontrol agents.

Members of Pseudomonas are Gram-negative, aerobic (able to consume oxygen) rods or cocci. They are flagellated so they can move around. Most produce a slime layer that cannot be phagocytosed, and which aids in the production of surface-colonising biofilms P. fluorescens is easily recognised as it secretes large amounts of fluorescent, yellow-green siderophores under iron-limited conditions. This species colonises plant roots. The opportunistic animal pathogen P. aeruginosa similarly secretes bright blue-green siderophores. Infection from it is usually accompanied by a "fruity" odor.

P. aeruginosa usually causes problems to humans who have already have had their immune systems weakened. This bacteria usually infects the urinary tract, burns, wounds, and also causes other blood infections. One in ten hospital acquired infections is from Pseudomonas. Cystic fibrosis patients are also predisposed to aeruginosa infection of the lungs.

Pseudomonas are able to grow in unexpected places. They have been found in areas where a lot of pharmaceuticals are prepared. Any carbon source, such as soap residue or cap liner adhesives is a suitable place for them to thrive. Other unlikely places where they have been found include antiseptics such as ammonium compounds and bottled mineral water. This ability to thrive in harsh conditions is a result of their hearty cell wall that contains porins. Their resistance to most antibiotics is attributed to their rapid efflux pumps which pump out the antibiotics before they are able to work.

Common hygiene practices should help to ward off any unwanted infections by this bacterium. If a more serious infection occurs, it can be treated with antibiotics such as piperacillin, imipenem, tobramycin, or ciprofloxacin, among others.

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