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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
“Collins English Dictionary — Complete & Unabridged” 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012


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


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Word History and Origins

Origin of Gram-negative1

First recorded in 1905–10; Gram's method
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Example Sentences

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

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

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

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

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

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