gram-negative

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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

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 ?
Comparison of test methods for detecting metallo-p-lactamase-producing Gramnegative bacteria.
All CecPs were bactericidal against Gram-positive such as Staplyococcus aureus, Bacillus subtilis, Micrococcus luteus, and Gramnegative bacteria, including Pesudomonas aeruginosa, Salmonella typhimurium and E.
The authors state: "Although most studies have showed (sic) Escherichia coli and Klebsiella spp as the most prevalent ESBL producing Gramnegative bacteria, Enterobacter spp was the most prevalent ESBL producing Gram-negative bacteria from surgical wounds, while Escherichia coli and Acinetobacter were the most prevalent ESBL producing bacteria from blood stream infections in our study.
This was a poorly written article and while the overall conclusions about prevalence of ESBL Gramnegative bacteria may have some value, this was lost in the poor presentation and the clear discrepancies between the text and the data provided.
Given that colonization with gramnegative bacteria is relatively uncommon, detecting such on endoscopic culture in acute exacerbations of chronic rhinosinusitis likely means that the patient has a true pathogenic infection, and antibiotic treatment can be considered.
on the antimicrobial activity of Laetiporus sulphureus that showed that Gramnegative bacteria were less susceptible than Grampositive strains.
The uncommon features were tetracycline resistance mediated by tet(W), increasingly detected in gram-positive and in gramnegative bacteria (5) but never previously reported in S.