Gram-positive

[gram-poz-i-tiv]

adjective

(often lowercase)

1. (of bacteria) retaining the violet dye when stained by Gram's method.

Gram-positive

adjective

1. designating bacteria that retain the violet stain in Gram's method

gram-positive

1. Relating to a group of bacteria that turn a dark-blue color when subjected to a laboratory staining method known as Gram's method. Gram-positive bacteria have relatively thick cell walls and are generally sensitive to the destructive effects of antibiotics or the actions of the body's immune cells. Gram-positive bacteria include beneficial nitrogen-fixing bacteria in soil, as well as the bacteria that cause anthrax, botulism, leprosy, tuberculosis, scarlet fever, and strep throat.

2. Compare gram-negative

Word History and Origins

Origin of Gram-positive¹

First recorded in 1905–10; Gram's method

Example Sentences

Gram-positive and gram-negative bacteria differ in the composition of their cell walls.

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"We have pretty strong evidence that this new structural class is active against Gram-positive pathogens by selectively dissipating the proton motive force in bacteria," Wong says.

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Hiley envisioned them as the “Gram twins,” representing two different types of bacteria: Gram-positive and Gram-negative.

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However, this did not happen with exposure to Gram-positive bacteria, which lack lipopolysaccharides in their cell membranes.

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L. monocytogenes is a Gram-positive bacterium, which means that it has a single lipid membrane and a thick cell wall.

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