Stains and Tests

• Simple Stain: A stain that is used to identify the presence of a particular substance. ( single stain )
• Differential stains: A stain that can be used to differentiate between two or more substances. ( double stain )
• Negative stain: A stain that is used to darken the color of a specimen.
• Primary Stain: A stain that is applied to a specimen before it is placed in a secondary stain.
• Mordant: A substance that will bind to the dye and make it more visible
• Decolorizer: A chemical that removes color from a solution.
• Counterstain: A second stain that is added to a slide after the primary stain has been removed, which serves as a background color.
• Crystal Violet: A basic dye that produces a blue-purple color when bound to acidic groups on cells.
• Iodine: An iodide salt that forms an insoluble complex with crystal violet, producing a purple color.
• Acid Alcohol: An alcoholic solution containing acetic acid, used to decolorize cells that have not retained crystal violet during Gram's method.
• Safranin: A basic dye that produces a red color when bound to acidic groups on cells.
• Gram Positive Bacteria: Retains the crystal violet stain due to their thick peptidoglycan layer, resulting in a deep purple color.
• Gram Negative Bacteria: Decolorized by the acid alcohol, leaving only the counterstained safranin, resulting in a pink or red color.
• Ziehl-Neelsen: A stain used to detect the presence of gram-negative bacteria.
• Kinyoun method:  uses carbol-fuchsin as a primary stain, followed by decolorization with an acid-alcohol solution and methylene blue as a counterstain.
• Acid Fast: A bacterium that produces a pigment that stains red in the presence of acid
• Non-acid fast: Stain the bacteria with methylene blue
• Carbolfuchsin: A dye that stains the bacterial cell wall pink
• Tergitol: Chemical used in the Kinyoun method of acid fast stains to stain the mycobacterium
• Mycobacterium and Nocardia are the only two acid fast bacterias
• Gram Staining Procedure: Crystal violet for 1 min, rinse with water, add Grams iodine for 1 min, rinse with water, then tilt slide add decolorizer 95% ethyl alcohol.
• Acid Fast Procedure: Carbolfuschin 5 mins, rinse, Acid alcohol 20-30 secs, and Methylene blue for 1 min