Ashdown's medium

[1] It is used for the selective isolation of B. pseudomallei from clinical specimens taken from non-sterile sites (e.g., sputum)[2] as well as to produce the characteristic morphology of B.

[3] The medium contains crystal violet and gentamicin as selective agents to suppress the growth of other bacteria.

Colonies of B. pseudomallei also take up neutral red which is present in the medium, and this further helps to distinguish it from other bacteria.

B. pseudomallei usually produces flat wrinkled purple colonies on Ashdown's agar.

Ashdown's medium has the advantage of being extremely cheap to produce: the cost of each plate is only US$0.04.