Gram-positive

American  

[gram-poz-i-tiv] / ˈgræmˈpɒz ɪ tɪv /

adjective

(often lowercase)

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

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Gram-positive British  

adjective

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

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gram-positive Scientific  

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

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Etymology

Origin of Gram-positive

First recorded in 1905–10; Gram's method

Example Sentences

She added that the drugs did not provide effective coverage against a Gram-positive organism, which was the most likely pathogen causing the infection.

From BBC • Mar. 11, 2026

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

From Science Daily • May 29, 2024

"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.

From Science Daily • Dec. 21, 2023

The left illustration shows the cell wall of Gram-positive bacteria.

From Textbooks • Jan. 1, 2015

In the early stages of incubation, at 100° to 112° F., the bacilli are uniform in size and intensely Gram-positive; in succeeding stages the irregular, vacuolated, inflated, and ruptured forms predominate.

From The Bacillus of Long Life a manual of the preparation and souring of milk for dietary purposes, together with and historical account of the use of fermente by Douglas, Loudon