Gram staining is perhaps relied upon too much and many scientists are aware of the limitations of the Gram stain test. However, the test’s few flaws do not prevent the test from being implemented for both clinical and research purposes. Gram staining is an empirical test that is used to identify bacteria. It is a useful tool. The two categories that most species of bacteria fall under are Gram positive bacteria and Gram negative bacteria. Gram positive bacteria react to the Gram test by absorbing the dye and artificially adopting a violet or dark blue color artificially.
The purpose of the gram test is to make bacteria more visible. In addition, Gram positive bacteria all have a exterior membrane that is composed cytoplasmic lipids with a thick peptidoglycan layer to protect the organism. Some species of bacteria have capsules with polysaccharides to hide the antigenic signature. Antigens are chemical substances that function as “finger prints.” Immune systems keep watch for these identifying signals. If a hostile antigen is identified, then an immune response is triggered and the bacteria is subsequently mobbed by angry immune cells. These polysaccharide capsules are cloaking devices that protect the organism from immune responses. The stain also reveals if the flagella in some species of bacteria. Flagella are hair like appendages that help bacteria move about their hosts faster. Flagella help bacteria swim through bodily fluids.
Most pathogenic bacteria in humans are gram positive bacteria. Therefore, most bacteriological tests on human extracted cultures are stained and revealed under the microscope. The almost all members of the bacteria phylum firmicutes are gram positive bacteria. Famous members of this phylum are most species of cocci bacteria (spherically shaped bacteria. Examples of cocci bacteria are staphylococcus, streptococcus, enterococcus, and most other bacteria with the “-coccus” suffix. Clostdrium, bacillus, and listeria genera are also members of gram positive bacteria category.