Gram-negative rods.

0.5-0.8 by 1.5-3.0 µm

they are usually thinner than Enterobacteriaceae

Obligate Aerobic

BA: 3 colony types:
1) small, rough, wrinkled
2) large, flat and spreading, serrated edge and a metallic sheen (associated with autolysis of the colony)
3) mucoid, sphere, smooth surface

Often they are ß-hemolytic.
Colonies tend to swarm.

They produce a blue-green metallic pigment (pyocyanine).

The blue-green color is a mixture of pyocyanine and pyoverdine.

Other colors pigment:
- yellow green - pyoverdine (Fluorescens group)
- reddish brown - pyorubrine
- brown black - pyomelanine

Colonies and surrounding medium have this color.

Mucoid isolates from CF(often poor prognosis) patients may undergo several phenotypic changes, including slow growth, loss of motility, and loss fof pigment production.
Some strains produce many extracellular polysaccharide slime, which grow as slimy colonies.

These are often non-pigmented colonies, and often have a slow oxidase reaction.
These are common in CF patients.

McConkey: growth, non lactose fermenter
often with blue or metallic sheen colonies

BBAØ: no growth

Odor/smell
Grape-like odor, caused by the production of pyocyanine

Bouillon
In bouillon the P.aeruginosa grows with a fleece on the surface.
Production of pyocyanin, water-soluble blue pigment of Pseudomonas aeruginosa

James Versalovic et al.(2011) Manual of Clinical Microbiology 10th Edition