Different Staining

Simple stain

Used to highlight microorganisms to determine cellular shapes and arrangements. Aqueous or alcohol solution of a single basic dye stains cells.

Gram

Used to distinguish among different kinds of bacteria.

Gram-positive

Bacteria retain the crystal violent stain and appear purple.

Gram-negative

Does not retain the crystal violent stain; they remain colorless until counterstained with safranin and the appearance of pink.

Acid-fast

Used to distinguish Mycobacteria species and some specific of Nocardia.

Acid-fast Bacteria

Stained with carbolfuchsin and treated with acid-alcohol, remains red and retains carbolfuchsin stain.

Non acid-fast bacteria

Stained and treated the same, then stained with methylene blue, appearance will be blue since losing carbolfuchsin stain and are then are able to accept the methylene blue stain

Special

Used to color and isolate various structures, such as capsules, endospores, and flagella; sometimes used as a diagnostic aid.

Negative

Used to demonstrate the presence of capsules. Appear as unstained holos around bacterial cells and stand out against contrasting background.

Endospore

Used to detect endospores in bacteria. When malachite green is applied to a heat-fixed smear of bacterial cells, the stain penetrates the endospores and stains them green. When safranin is then applied, it stains the remainder of the cells red or pink.

Flagella

Used to demonstrate the presence of flagella. A mordant is used to build up the diameters of flagella until they become visible microscopically when stained with carbolfuchsin.