Gram stain lab report - by asem shadid

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College of Medicine

Al-Imam Mohammad Bin Saud Islamic University

First year

2013 – 2014

By : Asem Shadid – 435032467

Gram Staining Method

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• Asem Mustafa Shadid

• First year

• 435032467

Name :

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Microbiology lab report : 1- introduction (Gram Staining) 2-Requirements (Reagents) 3-Method 4-Observations

• Contents : -

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Introduction :

• The Gram staining

• The Gram staining method, named after Hans Christian Gram.

• the Gram's method are commonly classified as Gram-positive and Gram negative.

• Others that are not stained by crystal violet are referred to as Gram negative, and appear red.

• A Gram stain and culture of the material from an infected site are the most commonly performed microbiology tests used to identify the cause of a bacterial infection.

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• After culture a Gram stain is performed to help determine the type of bacteria present and to help determine what other tests may need to be performed to definitively identify the cause of infection.

• Viruses cannot be detected with a Gram stain.

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Principle of stainingStains → combine chemically with the bacterial protoplasm.

Commonly used stains are salts: Basic dyes: colored cation + colorless anion e.g. methylene blue (methylene blue chloride) MB+ + Cl-

Acidic dyes: colored anion + colorless cation e.g. eosin ( Na+ + eosin-).

Bacterial cells are slightly negatively charged ( rich in nucleic acids bearing negative charges as phosphate groups)

→ combine with positively charged basic dyes

Acidic dyes do not stain the bacterial cell → can stain the background material with a contrasting color.

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Requirements (Reagents)

• 1. Gather all equipment and supplies– Gram stain– Microscope slides– Heat source– Sterile swab– Culture or specimen– Microscope– Label the slide with the patient’s initials or the specimen number.

2. Choose an isolated colony off of the agar plate and obtain bacteria with a sterile swab.

3. Place the swab on the microscope slide and spread the colonies in a circular motion.

4. Heat fix the microorganisms

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Purple color

Orange color

Purple color

Method

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Purple color

White color

Purple color

White color

Purple color

White color

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Purple color Pink color

Pink colorPurple color White color

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- Blot the slide and read with the oil immersion lens of the microscope. Look for Gram-positive and Gram-negative bacteria.

Pink color

White color

Purple color

Purple colorPurple color

Purple color

Purple color

Purple color

OVERVIEW

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13Designed By : Asem Shadid – 435032467