Task 1: Bacterial Morphology and Gram Staining PDF

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Introduction:
There are two groups that bacterial cells can be classified into based on the cell structure and what the cell is made up of. These two categories are known as Gram-positive and Gram-negative bacteria. They are named after Hans Christian Gram who developed a technique called th...

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Task 1: Bacterial Morphology and Gram Staining Morgan McLaughlin 1/12/2020 Clinical Microbiology-C453

Task 1: Bacterial Morphology and Gram Staining Introduction: There are two groups that bacterial cells can be classified into based on the cell structure and what the cell is made up of. These two categories are known as Gram-positive and Gramnegative bacteria. They are named after Hans Christian Gram who developed a technique called the Gram Stain in 1884. This physician was able to decipher Gram-positive bacteria from Gramnegative bacteria by using a series of stains and washes. Due to the thick and mesh like layers of peptidoglycan in Gram-positive bacteria the dye using crystal violet is still visible after being rinsed away. This leaves the Gram-positive bacteria purple. With the Gram-negative bacteria the thin, single layer of peptidoglycan cell walls are left clear. They are counterstained with safranin and turn pink. Material and methods: The materials needed for this experiment include; Sample: Bacteria, Primary stain: Crystal Violet, Mordant: Gram’s Iodine, Decolorizing agent: Alcohol, Counterstain: Safranin. 1. After a bacterial smear is made on a slide and the slide is passed through a flame to affix it to the slide, you immerse the smear in crystal violet for one minute, and then rinse with water. All the cells on the slide will be purple. 2. Gram’s iodine is added to the slide, this helps the crystal violet bind to the cell walls in the staining process. After one minute the Gram’s iodine is rinsed off with water. 3. Quickly, the slide is rinsed with alcohol and then water. This will remove the crystal violet from the thin walls of a Gram-negative bacteria. 4. Safranin, a counterstain, is added for 30-60 seconds, rinsed away with water, and then blotted dry. This leaves the Gram-negative cells pink, making them easier to see. Results: The first image, Escherichia coli, is made up of pink rod like shape, bacilli. This slide consists of bacillus and diplobacilli. This sample of Ecsheria coli is a Gram-negative bacterium. The image of Staphylcoccus epidermidis contains purple clusters of sphere shape coccus. The purple staining of the Staphylococcus is consistent with this image being a Gram-positive bacterium.

Discussion: The method of Gram staining has proven to be very effective and accurate. It is important to diagnose the correct bacteria so physicians can properly treat an infection with the correct antibiotic. Gram-negative bacteria are less sensitive to Penicillin’s due to their outer layer that the antibiotic can not penetrate. They also have an endotoxin called lipopolysaccharide that

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releasees when the cell wall is damaged. This can cause a fever and dilated blood vessels, which can result in a rapid decrease in blood pressure. Because of this, medical providers must be careful in treating Gram-negative bacterial infections. It could result in worsening symptoms and even death for the patient.

Work Cited: Black, J. G., & Black, L. J. (2016). Microbiology: Principles and explorations (9th ed.). Hoboken, New Jersey: John Wiley & Sons. Print ISBN: 978-1-118-74316-4 Hands-on-Labs. (2015). Bacterial Morphology and Staining Techniques Experiment. Englewood, CO. Available from www.labpaq.com.

Shahi, K. (2015). Gram Staining Procedure. Retrieved from http://https://wiley.engagelms.com/learn/mod/book/view.php?id=25819...