Abstract

MOLLINEDO PATZI, Marcela Andrea  and  GONZALES VILLALOBOS, Cynthia. Bacterias Gram Negativas. Rev. Act. Clin. Med [online]. 2014, vol.49, pp. 2609-2613. ISSN 2304-3768.

In the field of microbiology, are called negative microorganisms when they have a different reaction to the Gram stain in their wall cell compared to Gram positive, as there are stained dark blue or violet, pink color. Gram-negative bacteria do not retain crystal violet dye during the coloring process because they have a very thin layer of peptidoglycan in their cell wall and its outer shell is covered by a membrane lipoprotein. Many species of Gram negative bacteria, are grouped into several families and there are different ways to rank them according to: form, optimum temperature, pH in which oxygen requirement to stay alive are developed, the latter point classifies these microorganisms in: strict aerobic bacteria, strictly anaerobic bacteria and facultative anaerobic bacteria. The pathogenicity of these bacteria due to the presence of lipopolysaccharides (endotoxins) in the outside of the cell membrane, these molecules elicit an immune response, for its antigen generates a wide spectrum of pathophysiological effects, which can trigger endotoxic shock or death.

Keywords : Gram negative bacteria; Gram stain; Bacterian's structure.