In microbiology, gram staining is an important test used because it can determine the presence of bacteria in a sample, as well as differentiate between the two distinct bacteria species, which are gram-positive and gram-negative bacteria. This test also is especially important in medicine because the identification of the specific pathogen can help in the treatment of a bacterial infection, notes Healthline.
Gram staining requires a sample, which can be blood, sputum or mucus, states Healthline. The process of identifying bacteria in the sample involves using different agents, such as crystal violet dye, iodine mordant, decolorant and safranin. After staining, bacteria differentiation is possible because gram-positive bacteria have a purple color while gram-negative bacteria have a pink color when viewed under a light microscope. A basic difference between these two types of bacteria is their cell walls.