gram-negative

(redirected from Gram negative bacteria)
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

gram-negative

 [gram-neg´ah-tiv]
losing the stain or decolorized by alcohol in Gram's method of staining; see Gram stain. This is a primary characteristic of bacteria having a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide.

gram-neg·a·tive

(gram-neg'ă-tiv), In this expression gram begins with lowercase g but Gram stain takes an uppercase G.
Refers to the inability of a type of bacterium to resist decolorization with alcohol after being treated with crystal violet. However, following decolorization, these bacteria can be readily counterstained with safranin, imparting a pink or red color to them when viewed by light microscopy. This reaction is usually an indication that the outer structure of the bacterium consists of a cytoplasmic (inner) membrane surrounded by a relatively thin peptidoglycan layer, which in turn is surrounded by an outer membrane. See: Gram stain.

gram-negative

/gram-neg·a·tive/ (-neg´ah-tiv) losing the stain or decolorized by alcohol in Gram's method of staining, characteristic of bacteria having a cell wall surface more complex in chemical composition than the gram-positive bacteria.

gram-negative

or

Gram-negative

(grăm′nĕg′ə-tĭv)
adj.
Of, relating to, or being a bacterium that does not retain the violet stain used in the Gram stain method.

gram-negative

Etymology: Hans C.J. Gram, Danish physician, 1853-1938; L, negare, to say no
having the pink color of the counterstain used in Gram's method of staining microorganisms. This property is a primary method of characterizing organisms in microbiology. Some of the most common gram-negative pathogenic bacteria are Bacteroides fragilis, Brucella abortus, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Neisseria gonorrhoeae, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, and Yersinia pestis.

gram-neg·a·tive

(gram-neg'ă-tiv)
Refers to the inability of a bacterium to resist decolorization with alcohol after being treated with Gram crystal violet. However, following decolorization, these bacteria can be readily counterstained with safranin, imparting a pink or red color to the bacterium when viewed by light microscopy.
See: Gram stain

Gram-negative

see GRAM'S STAIN.

Gram-negative

Refers to the property of many bacteria that causes them to not take up color with Gram's stain, a method which is used to identify bacteria. Gram-positive bacteria which take up the stain turn purple, while Gram-negative bacteria which do not take up the stain turn red.

gram-neg·a·tive

(gram-neg'ă-tiv)
Refers to the inability of a type of bacterium to resist decolorization with alcohol after being treated with crystal violet.

gram-negative,

n having the pink color of the counterstain used in Gram's method of staining microorganisms. Staining property is a common method of classifying bacteria. See also Gram's stain.

gram-negative

said of bacteria that are decolorized by alcohol in Gram's method of staining (see gram's stain), and are thus stained only with the counter stain (usually red). Gram-negative bacteria have a much thinner layer of peptidoglycan in the cell wall than Gram-positive bacteria.
References in periodicals archive ?
Additionally those antibiotics that were non specific against gram negative bacteria became more effective in the presence of euganol.
Centoxin, the first human monoclonal antibody to be used therapeutically, neutralizes the effects of the toxin released by gram negative bacteria, called endotoxin.
Viraguard(R) Hospital Disinfectant Towelettes constitute a broad spectrum, one-step, cleaning/disinfecting system that is effective against gram positive and gram negative bacteria, including resistant strains such as MRSA and VRE, encapsulated bacteria such as Tuberculosis producing Mycobacterium bovis (BCG), Trichophyton mentagrophytes fungus, Herpes simplex, and HIV-1 (the AIDS virus).
Gram negative bacteria, reagents for identification and sensitivity
SIGA's lead product development programs focus on biological warfare defense, mucosal vaccines for strep throat and sexually transmitted diseases, commensal bacteria for the delivery of vaccines and protein therapeutics and novel antibiotics for gram positive and gram negative bacteria.