Gram-negative bacterium

GC: n

S: WHO – (last access: 2 November 2019); NIH – (last access: 2 November 2019).

N: 1. Gram-negative (adj): gram-negative = not holding the purple dye when stained by Gram’s stain —used chiefly of bacteria. First Known Use of gram-negative: 1907.
– bacterium (n): New Latin, from Greek baktērion staff. First Known Use of bacterium: 1835. Plural: bacteria.

  • Generally used in plural: Gram-negative bacteria.

2. Gram-negative bacteria lose the crystal violet stain (and take the color of the red counterstain) in Gram’s method of staining. This is characteristic of bacteria that have a cell wall composed of a thin layer of a particular substance (called peptidoglycan).
3. The Gram-negative bacteria include most of the bacteria normally found in the gastrointestinal tract that can be responsible for disease as well as gonococci (venereal disease) and meningococci (bacterial meningitis). The organisms responsible for cholera and bubonic plague are Gram-negative.
4. The Danish bacteriologist J.M.C. Gram (1853-1938) devised this method of staining bacteria using a dye called crystal (gentian) violet. Gram’s method helps distinguish between different types of bacteria. The gram-staining characteristics of bacteria are denoted as positive or negative, depending upon whether the bacteria take up and retain the crystal violet stain or not.
5. Gram-negative bacteria cause infections including pneumonia, bloodstream infections, wound or surgical site infections, and meningitis in healthcare settings. Gram-negative bacteria are resistant to multiple drugs and are increasingly resistant to most available antibiotics. These bacteria have built-in abilities to find new ways to be resistant and can pass along genetic materials that allow other bacteria to become drug-resistant as well. CDC’s aggressive recommendations, if implemented, can prevent the spread of gram-negatives.
6. Gram-negative infections include those caused by Klebsiella, Acinetobacter, Pseudomonas aeruginosa, and E. coli., as well as many other less common bacteria.

S: 1. MW –; (last access: last access: 2 November 2019). 2 to 4. MN – (last access: last access: 2 November 2019). 5 & 6. CDC – (last access: 2 November 2019).

OV: gram-negative bacterium

S: TERMIUM PLUS – (last access: 2 November 2019)


CR: bacillus, bacterium, Gram-positive bacterium, Gram stain.