SGD On Gram Staining Procedure: Step-by-Step Microbiology Practical | MBBS

Описание: In this hands-on practical session for the MBBS 2024-2025 batch at Santiniketan Medical College, students learn the step-by-step procedure of Gram Staining to differentiate between Gram-positive and Gram-negative bacteria.

This video covers the entire laboratory process—from smear preparation to microscopic observation—providing a clear guide for medical students preparing for their university practical exams.

Key Laboratory Steps Covered:

Smear Preparation: How to correctly use a loop to pick a single bacterial colony and create a thin, uniform smear on a slide [01:29].

Heat Fixation: The proper technique for air-drying and heat-fixing the bacterial smear to ensure cells adhere to the slide [04:43].

Primary Staining: Application of Crystal Violet for 1 minute to stain all cells purple [05:44].

Mordant Application: Using Gram’s Iodine to fix the crystal violet within the cell walls.

Decolorization: The most critical step—using Acetone or Alcohol for 2-3 seconds to differentiate cell types [06:53].

Counterstaining: Application of Safranin for 1 minute to stain decolorized Gram-negative bacteria pink/red [10:39].

Microscopic Observation: Identifying Gram-negative bacilli (pink) vs. Gram-positive cocci (purple) under the microscope [11:32].

Key Timestamps for Quick Reference:

[01:01] - Sterilizing the loop (Red-hot sterilization).

[01:29] - Picking a single colony from the culture plate.

[04:19] - Creating the bacterial smear with normal saline.

[04:43] - Air drying and heat fixation technique.

[05:44] - Applying Crystal Violet (Primary Stain).

[06:53] - Decolorization with Acetone (The critical step).

[10:39] - Applying Safranin (Counterstain).

[11:32] - Results: Identifying Gram-negative vs. Gram-positive bacteria.


SANTINIKETAN MEDICAL COLLEGE & HOSPITAL
Real Classroom Demonstration/Lecture
On: MICROBIOLOGY by Dr. Chinmoy Bandopadhyay
(MBBS Batch: 2024-25)
Conducted on: 29-12-25