Comparison Between Gram Stain and Acid Fast
|S.No||Characteristics||Gram Stain||Acid Fast|
|1||Definition||Gram stain refers to a staining technique for the preliminary identification of bacteria, in which a violet dye is applied, followed by a decolorizing agent and then a red dye.||The acid-fast stain refers to a differential stain used to identify acid-fast organisms such as members of the genus Mycobacterium.|
|2||Purpose||Gram stain is used to distinguish between gram-positive bacteria and gram-negative bacteria.||A cid-fast stain is used to distinguish between acid-fast bacteria and non-acid fast bacteria.|
|3||Type of characterization||Gram stain characterizes bacteria with different types of cell walls||Acid-fast stain characterizes bacteria with mycolic acid in the cell wall.|
|4||Primary Stain||Crystal violet is used as a primary stain in Gram staining.||Carbol fuchsin is used as a primary stain in Acid Fast staining.|
|5||Mordant||Iodine is used as mordant in Gram staining.||Phenol acts as a mordant in Acid Fast staining.|
|6||CounterStain||Safranin is used as a counterstain in Gram staining.||Methylene blue is used as a counterstain in Acid Fast staining.|
|7||Appearing||In Gram stain, Gram-positive bacteria appear in blue color while Gram-negative bacteria appear in red color.||In acid-fast stain, acid-fast bacteria appear in red color while non-acid-fast bacteria appear in blue color.|
Example of Gram-Positive Bacteria: Lactobacillus, Nocardia, Bacillus, Clostridium, Staphylococcus, Propionibacterium, Actinomyces, Streptomyces, Enterococcus, Listria,Gardnerella, Cornyebacterium, Mycoplasma, Streptococcus.
Example of Gram-Negative Bacteria: Helicobcater, Escherichia, Shigella, Hemophilus, Neisseria, Pseudomonas, Klebsiella, Enterobacter, Vibrio, Chlamydia, Salmonella.
|Nocardia spp (Partial Acid Fast), Rhodococcus spp (Partial Acid Fast), Legionella micdadei (Partial Acid Fast in tissue), Cyst of Cryptosporidium (Acid Fast), Cyst of Isospora (Acid Fast)|