What do gram negative bacteria typically look like when stained?

Gram negative bacteria typically appear red or pink when subjected to a gram stain procedure. This staining differentiation is fundamental in microbiology, based on the structure of the bacterial cell wall.

Gram negative bacteria have a thin peptidoglycan layer surrounded by an outer membrane, which is composed of lipopolysaccharides. During the gram staining process, the initial crystal violet dye is unable to penetrate the outer membrane effectively, especially after the application of a decolorizer. This leads to the loss of the crystal violet stain. Following this, a counterstain, usually safranin, is applied, which is able to penetrate and stain the now decolorized cells. The result is that these bacteria take on the pink or red coloration.

This characteristic staining pattern is essential for identifying bacterial species and informing treatment options, as gram negative bacteria often show different responses to antibiotics compared to their gram positive counterparts. Understanding this staining process allows for quick classification of bacteria in a clinical setup, which is crucial for appropriate management of infections.