Thursday, January 25, 2024

Which of the following is an enrichment medium.. Thiocyanate broth

Which of the following is an enrichment medium:

  • A- CLED.
  • B- BAP.
  • C- MAC.
  • D- Thiocyanate broth.
  • E- Chocolate agar.

All of the options you listed are enrichment media! Each one has specific properties that make it suitable for growing different types of microorganisms.

Here's a breakdown of each option:

A. CLED (Cystine Lactose Electrolyte Deficient Agar):

  • Used for isolating and differentiating lactose-fermenting from non-fermenting Gram-negative bacteria.
  • Lactose fermentation produces acid, turning the media yellow.
  • Contains cystine, which helps in the recovery of fastidious Gram-negative bacteria.

B. BAP (Brain-Heart Infusion Agar with Blood):

  • Enriched with sheep or horse blood, providing additional nutrients for fastidious bacteria.
  • Used for isolating a wide range of bacteria, including Streptococcus, Staphylococcus, and Haemophilus species.
  • Blood agar can also be used to differentiate between hemolytic (red blood cell lysing) and non-hemolytic bacteria.

C. MAC (MacConkey Agar):

  • Selective and differential medium for Gram-negative bacteria.
  • Contains bile salts and crystal violet, which inhibit the growth of Gram-positive bacteria.
  • Lactose fermentation produces acid and bile salt precipitate, turning colonies pink.
  • Non-lactose fermenters remain colorless.

D. Thiocyanate broth:

  • Enriched with sodium thiocyanate, which is selective for Pseudomonas aeruginosa.
  • Pseudomonas metabolizes the thiocyanate, producing cyanide, which turns the broth red.

E. Chocolate agar:

  • Enriched with heated sheep or horse blood, providing additional nutrients and growth factors for fastidious bacteria, such as Haemophilus influenzae and Neisseria meningitidis.
  • Heating the blood creates a chocolate-brown colored medium.

So, all of these options are considered enrichment media, each with its own unique purpose and target organisms. The best choice for a particular situation will depend on the specific type of bacteria you're trying to isolate and grow.