Selective Culture Media

Selective culture media are used to recover pathogens from samples containing mixture of microorganisms such as feces. For example, Salmonella-Shigella (SS) agar contains about five times the concentration of bile salts compared with MacConkey agar and is more inhibitory to E.coli and more selective for the recovery of Salmonella species from stool cultures.

Various compounds may serve to inhibit the growth of certain undesired microorganisms, thus making the medium selective. Relative concentrations of these substances are important in determining the selectivity of the medium.

  1. Aniline dyes (e.g., brilliant green and eosin)
  2. Heavy metals (e.g., bismuth)
  3. Chemicals (e.g., azide, citrate, deoxycholate, selenite, and phenyl ethyl alcohol), and
  4. Antimicrobial agents (e.g., neomycin, colistin, vancomycin, and chloramphenicol)
Phenylethyl Alcohol Agar: Composition, Preparation, Uses

Phenylethyl Alcohol Agar: Composition, Preparation, Uses

Phenylethyl alcohol agar (PEA) is a selective medium used to cultivate Gram-positive cocci, from a sample containing a mixed flora.

Tinsdale Agar: Composition, Preparation, Uses

Tinsdale Agar: Composition, Preparation, Uses

Tinsdale Agar is used for the selective isolation and differentiation of C. diphtheriae from diphtheroids.

DCA Agar: Composition, Colony Characteristics

DCA Agar: Composition, Colony Characteristics

Deoxycholate citrate agar is used for the selective isolation and differentiation of Salmonella and Shigella species.

Bismuth Sulfite Agar: Composition, Uses, Colony Morphology

Bismuth Sulfite Agar: Composition, Uses, Colony Morphology

Bismuth sulfite agar is a modification of original Wilson and Blair medium used for the isolation of Salmonella typhi and other salmonellae.

Salmonella-Shigella (SS) Agar

Salmonella-Shigella (SS) Agar

Salmonella-shigella (SS) agar is commonly used for the selective isolation and differentiation of Salmonella and Shigella.

Modified Thayer-Martin Agar: Preparation, Uses

Modified Thayer-Martin Agar: Preparation, Uses

Thayer-Martin agar is a selective medium used for the isolation of Neisseria gonorrheae from specimens containing a mixed flora of bacteria.

Sabouraud Agar (SDA): Composition, Uses, Colony Morphology

Sabouraud Agar (SDA): Composition, Uses, Colony Morphology

Originally formulated for dermatophyte growth and pigment production, SDA is used for growth and maintenance of fungi.

Baird-Parker Agar: Preparation, Composition, and Uses

Baird-Parker Agar: Preparation, Composition, and Uses

First reported by Baird–Parker, it is a selective medium for the enumeration of Staphylococcus aureus in foods.

Cetrimide Agar: Composition, Preparation, Uses

Cetrimide Agar: Composition, Preparation, Uses

Cetrimide agar test the ability of an organism to grow in the presence of cetrimide.

Xylose Lysine Deoxycholate (XLD) Agar

Xylose Lysine Deoxycholate (XLD) Agar

XLD Agar is a selective and differential medium for the isolation, cultivation, and differentiation of gram-negative enteric microorganisms.

Hektoen Enteric (HE) Agar: Composition, Uses

Hektoen Enteric (HE) Agar: Composition, Uses

Hektoen Enteric Agar (HE) is a selective and differential medium to isolate and differentiate Salmonella and Shigella from other Enterobacteriaceae.

New York City Medium: Composition, Uses

New York City Medium: Composition, Uses

New York City medium is primarily designed for the isolation of pathogenic Neisseria. It also supports the growth of genital mycoplasmas.

TCBS Agar: Composition, Preparation, Uses

TCBS Agar: Composition, Preparation, Uses

TCBS agar is a selective as well as differential culture medium used for selective isolation and differentiation of Vibrio species.

EMB Agar: Composition, Principle, and Colony Morphology

EMB Agar: Composition, Principle, and Colony Morphology

Eosin methylene blue (EMB) agar is a selective and differential medium used to isolate fecal coliforms.

MacConkey Agar: Composition, Uses, Colony Characteristics

MacConkey Agar: Composition, Uses, Colony Characteristics

Selective (against gram-positive bacteria) and differential culture medium (LF and NLF), commonly used for the isolation of enterics.

Mannitol Salt Agar: Principle, Uses, and Results

Mannitol Salt Agar: Principle, Uses, and Results

Mannitol Salt Agar selects and differentiates Staphylococcus species. Staphylococcus aureus ferments mannitol and gives yellow colonies.