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Book

Gram-Positive Bacteria

Omeed Sizar  1 , Stephen W. Leslie  2 , Chandrashekhar G. Unakal  3
In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan.
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Book

Gram-Positive Bacteria

Omeed Sizar et al.
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Excerpt

Health professionals need to understand the important difference between gram-positive and gram-negative bacteria. Gram-positive bacteria are bacteria classified by the color they turn in the staining method. Hans Christian Gram developed the staining method in 1884. The staining method uses crystal violet dye, which is retained by the thick peptidoglycan cell wall found in gram-positive organisms. This reaction gives gram-positive organisms a blue color when viewed under a microscope. Although gram-negative organisms classically have an outer membrane, they have a thinner peptidoglycan layer, which does not hold the blue dye used in the initial dying process. Other information used to differentiate bacteria is the shape. Gram-positive bacteria comprise cocci, bacilli, or branching filaments.

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Conflict of interest statement

Disclosure: Omeed Sizar declares no relevant financial relationships with ineligible companies.

Disclosure: Stephen Leslie declares no relevant financial relationships with ineligible companies.

Disclosure: Chandrashekhar Unakal declares no relevant financial relationships with ineligible companies.

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