adjective (often lowercase)
- (of bacteria) retaining the violet dye when stained by Gram’s method.
- designating bacteria that retain the violet stain in Gram’s method
- Of, relating to, or being a bacterium that retains the violet stain used in Gram’s method.
- 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. Compare gram-negative.