Q.1
Ina plate of Baird-Parker agar, if you observe shiny, convex, black or dark gray colonies surrounded by a clear zone, which
organism would you suspect as the most likely causative agent?”
EXPLANATION
Diagnostic Selective & Differential Media: Baird-Parker, XLD, EMB & Biochemical Identifications
- Diagnostic Colony Morphology on Baird-Parker Agar:
- Selective & Differential Media for Staphylococcus aureus:
- Tellurite Reduction: S. aureus reduces potassium tellurite to metallic tellurium, producing shiny, convex, jet-black to dark grey colonies.
- Egg Yolk Reaction: Secretion of lecithinase and lipase clears egg yolk lipovitellin, generating a distinct clear zone/halo around colonies with an inner precipitate ring.
- Conclusion: Staphylococcus aureus (Option 4).
Correct option: (4) Staphylococcus aureus
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