Gram-negative

[ gram-neg-uh-tiv ]

adjective

, (often lowercase)

1. (of bacteria) not retaining the violet dye when stained by Gram's method.

Gram-negative

adjective

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

gram-negative

1. Relating to a group of bacteria that do not change color when subjected to the laboratory staining method known as Gram's method or Gram's stain. Gram-negative bacteria have relatively thin cell walls and are generally resistant to the effects of antibiotics or the actions of the body's immune cells. Gram-negative bacteria include E. coli and the bacteria that cause gonorrhea, typhoid fever, rickettsial fever, cholera, syphilis, plague, and Lyme disease.
2. Compare gram-positive

Word History and Origins

Origin of Gram-negative¹

First recorded in 1905–10; Gram's method

Example Sentences

The organism is a short, thick diplobacillus, is frequently intracellular, and is Gram-negative (Fig. 126).

From Project Gutenberg

And here it says, "Gram negative, diplococci intra- and extra-cellular morphological resembling neisseria gonococci."

From Project Gutenberg

Young individuals are stained by Gram's method; older individuals are, however, Gram negative.

From Project Gutenberg

The bacillar threads are in places Gram-negative, in others Gram-positive, and bear small club-like swellings (see Fig. 14).

From Project Gutenberg

The Gram-positive bacteria are violet and the Gram-negative are red.

From Project Gutenberg