Question

Blood agar is an example of which type of medium?

• A. Enriched media
• B. Indicator media
• C. Enrichment media
• D. Selective media

Hint:

Adding blood as an extra nutrient to a basal agar defines this category.

Answer 1

The Correct Option is A

Step 1: Concept. Culture media are classified by their function. An enriched medium has extra nutrients, such as blood, serum, or egg, added to a basal medium so that fastidious organisms can grow.

Step 2: Why enriched media. Blood agar is nutrient agar enriched with 5 to 10 percent sheep or human blood. The added blood supplies growth factors that allow demanding bacteria to multiply, so it is the classic example of an enriched medium. Option (a) is correct.

Step 3: Why the others are wrong. An indicator medium contains a dye or chemical that changes colour to show a metabolic reaction, for example MacConkey agar for lactose fermentation. An enrichment medium (a liquid) favours one organism while suppressing others, for example selenite F or tetrathionate broth for Salmonella. A selective medium contains inhibitors that stop unwanted organisms, for example DCA or TCBS. Blood agar fits none of these.

Step 4: Note. Blood agar also reveals haemolysis patterns (alpha, beta, gamma), which adds differential value, but its primary classification is enriched.