Pharma Interview Q and A Sep-30-21

September 30, 2021: Pharmaceutical Interview Questions and Answers

#LactophenolCottonBlueStain #FungalStaining #ZiehlNeelsenStain #AcidFastStain

1. What is Lactophenol cotton blue stain or fungal staining?

Lactophenol cotton blue stain is used to examining yeast and filamentous fungi under microscope.

Phenol acts as a disinfectant to kill living organisms

Lactic acid used to preserve the fungal structures

Cotton blue is used to stain fungal cell wall and other fungal structures

On staining, it fungus will be with blue colored spores and structures, such as hyphae.

The identification of fungi using macroscopic and microscopic techniques is difficult and requires a trained eye.

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2. What reagents used to prepare Lactophenol cotton blue staining solution?

Distilled water

Cotton Blue or Aniline Blue

Phenol Crystals


Lactic acid

70% ethanol

3. What is use of Ziehl-Neelsen stain?

The objective of Ziehl-Neelsen stain is to differentiate bacteria into acid fast group and non-acid fast groups.

4. What Acid-Fast stain called as Ziehl-Neelsen stain?

This technique was first developed by Ziehl and later on modified by Neelsen, therefore, this method is also called as Ziehl-Neelsen staining techniques.

ReagentsColor of Acid fastColor of Non-acid fast
Primary dye – Carbol fuchsinRedRed
Decolorizer – Acid alcoholRedColorless
Counter stain – Methylene blueRedBlue
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