What is a Gram Stain?
A Gram stain refers to a positive or negative test result produced when an iodine wash is introduced to a culture of bacteria in order to identify its species. This test, known as Gram staining, works by detecting the presence of lipopolysaccharides (lipoglycans) and peptidoglycans (mureins) contained within the cell walls of the bacteria sample. If low concentrations exist, then the sample is said to be Gram-positive. In contrast, high levels of peptidoglycans without lipopolysaccharides indicate that the sample is Gram-negative. First, the bacteria sample is placed on a glass slide and heated only to the point of rendering it innocuous in terms of being infectious to the handler. Next, the bacteria sample is treated with a gentian violet-iodine solution for up to sixty seconds. The slide is then gently rinsed under clean water and the Gram solution is applied, which is a mixture of iodine and potassium iodide diluted in water. This step triggers a reaction to the gentian violet compo
Related Questions
- Based on the results of the gram stain, catalase, PYR, and LAP tests, should this culture be reported as positive for VRE?
- coryneform bacteria seen in gram stain of sputum culture and the coryneform gpb grows 4+. Should further id be done?
- How do you explain the chemical basis of gram stain technique?
