Question

Match List-I with List-II

List-I (Media)	List-II (Bacteria)
(A) Kings medium	(I) Pseudomonas aeruginosa
(B) Baird Parker agar	(II) Staphylococcus aureus
(C) PALCAM agar	(III) Listeria monocytogenes
(D) Desoxycholate citrate agar	(IV) Salmonella spp.

Choose the correct answer from the options given below

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (IV), (B) - (II), (C) - (III), (D) - (I)
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

Remember these diagnostic selective media associations:
- King's Medium \(\rightarrow\) Pseudomonas (fluorescent pigment).
- Baird-Parker \(\rightarrow\) Staphylococcus (black colonies with clear zone).
- PALCAM \(\rightarrow\) Listeria (black esculin hydrolysis halo).
- DCA \(\rightarrow\) Salmonella/Shigella (enteric pathogens).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Selective and differential culture media are essential tools in microbiology for isolating, enumerating, and identifying specific bacterial genera or species.
These media use selective agents (like antibiotics, dyes, or salts) to inhibit non-target flora and differential indicators (like pH indicators or chromogenic substrates) to distinguish target colonies.

Step 2: Detailed Explanation:
Let us match each culture medium in List-I with its target pathogen in List-II:
-(A) King's Medium:
King's media (such as King's A and King's B) are designed to isolate and differentiate Pseudomonas species.
King's B medium enhances the production of the fluorescent pigment pyoverdine by Pseudomonas aeruginosa, which fluoresces yellow-green under ultraviolet light.
Therefore, (A) matches with (I).
-(B) Baird-Parker Agar:
This selective and differential medium is used to isolate and enumerate Staphylococcus aureus.
It contains lithium chloride and potassium tellurite as selective agents to inhibit background flora.
Egg yolk emulsion is added as a diagnostic agent; S. aureus reduces tellurite to form black colonies and exhibits lecithinase activity, producing a clear zone around the colonies.
Therefore, (B) matches with (II).
-(C) PALCAM Agar:
PALCAM is a selective diagnostic agar used to detect and isolate Listeria monocytogenes from food and environmental samples.
It uses polymyxin, acriflavine, ceftazidime, and lithium chloride as selective agents.
It uses esculin and ferric ammonium citrate as an indicator system; Listeria hydrolyzes esculin, forming black colonies surrounded by a black halo.
Therefore, (C) matches with (III).
-(D) Desoxycholate Citrate Agar (DCA):
DCA is a selective and differential medium used to isolate enteric pathogens, particularly Salmonella and Shigella species.
Sodium desoxycholate and sodium citrate inhibit Gram-positive organisms and coliforms.
Lactose-fermenting organisms form red colonies, while non-fermenters like Salmonella form pale, colorless colonies (often with black centers due to \(H_2S\) production).
Therefore, (D) matches with (IV).
This matching sequence corresponds to Option (A).

Step 3: Final Answer:
The correct matching sequence is (A) - (I), (B) - (II), (C) - (III), (D) - (IV).