gram-negative


Also found in: Dictionary, Thesaurus, Acronyms, Encyclopedia, Wikipedia.
Related to gram-negative: gram-positive, gram-negative folliculitis

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

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-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.
References in periodicals archive ?
Metallo-[beta]-lactamases in gram-negative bacteria: Introducing the era of pan- resistance?
* It circumvents existing antibiotic resistance mechanisms and retains activity against contemporary multidrug-resistant Gram-negative clinical isolates
Of the 8,300 samples processed, 729(8.8%) samples of gram-negative microbes were isolated.
Antibiotic Susceptibility pattern of Enterobacteriaceae and non-fermenter Gram-negative clinical isolates of microbial resource orchid.
In order to generate a set of rules that could be used to make antibiotics that will target Gram-negative bacteria, the team screened 180 different chemicals for their ability to penetrate E.
Our study revealed a high proportion of ESBL- and carbapenemase-producing organisms among gram-negative bloodstream isolates during the study period from hospital inpatients in Yangon.
In the same study, the rate of gram-negative bacteria was 5.9% and the most common gram-negative bacterium was Escherichia coli.
This particularly clobbers gram-negative cells' outer structures, including the thin layer of peptidoglycan bound to the outer membrane, allowing the purple dye to flush away.
The Results: Freezing caused a significant lowering in pH, total bacterial count, and count of both gram-positive and gram-negative colonies.
[ClickPress, Wed Dec 31 2014] GlobalData's clinical trial report, "Gram-Negative Bacterial Infections Global Clinical Trials Review, H2, 2014" provides data on the Gram-Negative Bacterial Infections clinical trial scenario.
Summary: A series of NN-dimethyl-arylidene barbiturates 1-22 has been re-synthesized and evaluated against a number of Gram-positive Gram-negative bacteria and some fungal strains.
However, gram-negative organisms were identified in 7 of 21 (33.3%; 95% confidence interval: 13.3%-53.3%) birds.