Ashdown’s Agar- Composition, Principle, Preparation, Results, Uses

Ashdown's Agar

Ashdown’s medium is a selective culture medium for the isolation and characterization of Burkholderia pseudomallei (the bacterium that causes melioidosis). Ashdown’s medium was first described by LR Ashdown in 1979. Composition of Ashdown’s Agar Ingredients Gram/Litre Tryptone soya broth 10 g Agar                            15 g Glycerol 40 ml Gentamicin 4 mg Crystal violet 0.1% 5 ml Neutral Red 1% 5 ml Distilled water              950ml Principle of Ashdown’s Agar The medium contains crystal violet and gentamicin as selective agents to suppress the growth of other bacteria. Colonies of  B. pseudomallei … Read more

Biochemical Test of Bacteria

Biochemical Test of Bacteria

Biochemical reactions are very important in the identification of bacterial isolates and in the identification of different bacterial species. These tests depend on the presence of certain enzymes, such as catalase, oxidase, urease, gelatinase, etc., produced by the bacteria. Different bacteria produce varying spectra of enzymes. For example, some enzymes are necessary for the bacterium’s individual metabolism, and some facilitate the bacterium’s ability to compete with other bacteria or establish an infection. Tests that measure single bacterial enzymes are simple, … Read more

Biochemical Test of Burkholderia pseudomallei

Biochemical Test of Burkholderia pseudomallei

Image Source: University of Cambridge Some of the characteristics are as follows: Basic Characteristics Properties (Burkholderia pseudomallei) Capsule Positive (+ve) Catalase Positive (+ve) Citrate Positive (+ve) Flagella Positive (+ve) Gas Negative (-ve) Gelatin Hydrolysis Positive (+ve) Gram Staining Gram-negative (-ve) H2S Negative (-ve) Indole Negative (-ve) Motility Positive (+ve) Nitrate Reduction Positive (+ve) Oxidase Positive (+ve) Pigment Negative (-ve) Shape Rod-shaped; “safety pin” appearance (bipolar staining) Spore Negative (-ve) TSIA (Triple Sugar Iron Agar) K/NC/H2S -ve Urease Negative (-ve) Fermentation … Read more