Name: gram and acid-fast staining methods
Uploaded: 2025-06-12T09:26:11.000Z
Duration: 1 min 26 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

Middle School

Earth and Space Sciences

Space Systems

MS-ESS1-1

Differential Staining Technique

La tinción diferencial distingue los microorganismos en función de las propiedades de la pared celular, lo que ayuda a la identificación y clasificación de las bacterias.La tinción de Gram clasifica las bacterias como grampositivas o gramnegativas por su capacidad de retener el cristal violeta después de la decoloración con alcohol.Un delgado frotis de cultivo microbiano se extiende en un portaobjetos, se seca al aire y se fija con calor.El frotis se tiñe con violeta cristalino, se lava con agua y se trata con yodo, formando un complejo de violeta cristalino y yodo.Se usa alcohol para decolorar esta mancha hasta que la escorrentía sea clara, seguida de un enjuague con agua.Las bacterias grampositivas retienen la mancha púrpura debido a su gruesa capa de peptidoglicano.Por el contrario, las bacterias gramnegativas pierden la mancha púrpura a medida que el alcohol altera la membrana externa y lava el complejo cristalino de violeta-yodo.La safranina se utiliza para contrarrestar las bacterias gramnegativas de color rosa, mientras que las bacterias grampositivas permanecen de color púrpura.La tinción acidorresistente detecta las especies de Mycobacterium, cuyas paredes celulares cerosas ricas en ácido micólico resisten la decoloración.Las bacterias acidorresistentes retienen carbol fucsina, un tinte rojo, mientras que las células no acidorresistentes generalmente se contratiñen con azul de metileno.

técnica de tinción diferencial

La tinci&#243;n diferencial es una t&#233;cnica microbiol&#243;gica fundamental que aprovecha las variaciones en las estructuras de la pared celular para clasificar e identificar microorganismos. Esta t&#233;cnica facilita la diferenciaci&#243;n de bacterias, lo cual es esencial tanto en aplicaciones diagn&#243;sticas como en investigaciones. Dos de los m&#233;todos de tinci&#243;n diferencial m&#225;s utilizados son la tinci&#243;n de Gram y la tinci&#243;n &#225;cido-alcohol resistente, ambos basados en las diferencias qu&#237;micas y estructurales presentes en las paredes celulares bacterianas.
T&#233;cnica de tinci&#243;n de Gram
La tinci&#243;n de Gram diferencia las bacterias seg&#250;n la composici&#243;n de su pared celular, clasific&#225;ndolas en grampositivas o gramnegativas. Este procedimiento comienza con la preparaci&#243;n de un frotis bacteriano fijado al calor, que se ti&#241;e inicialmente con cristal violeta. A continuaci&#243;n, se a&#241;ade yodo, formando un complejo cristal violeta -yodo que queda atrapado en la pared celular. Posteriormente, se aplica un decolorante a base de alcohol que elimina este complejo de las bacterias gramnegativas, pero no de las grampositivas. La diferencia radica en la gruesa capa de peptidoglicano de las bacterias grampositivas, que retiene la tinci&#243;n p&#250;rpura. En cambio, las bacterias gramnegativas poseen una capa de peptidoglicano m&#225;s delgada y una membrana externa que se ve alterada por el alcohol, lo que provoca la p&#233;rdida de la tinci&#243;n p&#250;rpura. Luego se aplica safranina como colorante de contraste, lo que confiere a las bacterias gramnegativas un color rosado, mientras que las grampositivas permanecen de color p&#250;rpura.
T&#233;cnica de tinci&#243;n &#225;cido-alcohol resistente
La tinci&#243;n &#225;cido-alcohol resistente resulta especialmente &#250;til para la identificaci&#243;n de especies del g&#233;nero Mycobacterium, cuyas paredes celulares ricas en &#225;cido mic&#243;lico resisten la tinci&#243;n convencional y la decoloraci&#243;n. En este procedimiento, se aplica un colorante rojo, la carbolfucsina, sobre un frotis fijado al calor, frecuentemente con calor adicional, para facilitar la penetraci&#243;n del colorante en el m&#233;todo de Ziehl-Neelsen. Posteriormente, se utiliza una soluci&#243;n de alcohol &#225;cido para eliminar la tinci&#243;n de las c&#233;lulas no &#225;cido-alcohol resistentes. Las bacterias &#225;cido-alcohol resistentes, debido a sus paredes celulares cerosas, retienen la coloraci&#243;n roja, mientras que las c&#233;lulas no &#225;cido-alcohol resistentes se ti&#241;en de azul con un colorante de contraste, com&#250;nmente azul de metileno. Cabe destacar que el m&#233;todo de Kinyoun, una variante de la tinci&#243;n &#225;cido-alcohol resistente, no requiere calor para la aplicaci&#243;n de carbolfucsina.
Ambas t&#233;cnicas de tinci&#243;n son herramientas indispensables para la identificaci&#243;n microbiana, el diagn&#243;stico cl&#237;nico y la determinaci&#243;n de intervenciones terap&#233;uticas adecuadas. Por ejemplo, las bacterias gramnegativas suelen ser m&#225;s resistentes a ciertos antibi&#243;ticos debido a su membrana externa, lo que hace que su identificaci&#243;n sea cr&#237;tica para un tratamiento eficaz. Comprender estas t&#233;cnicas es crucial en microbiolog&#237;a y en la pr&#225;ctica cl&#237;nica, ya que permiten una identificaci&#243;n precisa y contribuyen a la selecci&#243;n adecuada de antibi&#243;ticos.

Técnica de tinción diferencial

La tinci&#243;n diferencial es una t&#233;cnica microbiol&#243;gica fundamental que aprovecha las variaciones en las estructuras de la pared celular para ...

Education

Educación

JoVE Core

Microbiology

Microbiología

Unit

Unidad

Introduction to Microbiology

Introducción a la microbiología

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

gram and acid-fast staining methods

Gram and acid-fast staining methods help scientists tell bacteria apart by looking at their cell walls. These differential stains are important in microbiology because they support identification, diagnosis, and research. They use structural and chemical differences in bacterial cell walls to separate microorganisms into clear groups.

Gram staining classifies bacteria as gram-positive or gram-negative. A heat-fixed bacterial smear is first stained with crystal violet, and iodine is added to form a crystal violet-iodine complex. Alcohol then acts as a decolorizer. It removes the complex from gram-negative cells but not from gram-positive cells.

The reason for this difference is the cell wall structure. Gram-positive bacteria have a thick peptidoglycan layer, which holds the purple stain. Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane. Alcohol disrupts that outer membrane, so the purple stain is lost. Safranin is then used as a counterstain. It turns gram-negative bacteria pink while gram-positive bacteria stay purple.

Acid-fast staining is used to identify Mycobacterium species. These bacteria have mycolic acid-rich cell walls, which resist normal staining and decolorization. Carbolfuchsin, a red dye, is applied to a heat-fixed smear. In the Ziehl-Neelsen method, heat is often used to help the dye enter the cell. Acid-alcohol then removes the stain from non-acid-fast cells.

Acid-fast bacteria keep the red stain because their waxy cell walls hold it. Non-acid-fast cells lose the red dye and are counterstained blue, usually with methylene blue. A related method, the Kinyoun stain, does not use heat for carbolfuchsin application. Both gram staining and acid-fast staining are essential for microbial identification, clinical diagnostics, and choosing the right treatment. Gram-negative bacteria can be more resistant to some antibiotics because of their outer membrane, so identifying them can guide therapy.

Gram and Acid-Fast Staining Methods

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simple staining technique

Staining Microbes for Shape and Arrangement

Simple staining helps reveal the size, shape, and arrangement of microorganisms under the microscope. It uses one dye to color the whole cell. That creates strong contrast between the cells and the background. A careful preparation step comes first. A small drop of microbial culture is spread on a clean glass slide to make a thin smear. The smear is air-dried and then heat-fixed, which means it is briefly passed over a flame. Heat fixation keeps the cells attached to the slide. It also helps...

differential staining technique

Gram and acid-fast staining methods help scientists tell bacteria apart by looking at their cell walls. These differential stains are important in microbiology because they support identification, diagnosis, and research. They use structural and chemical differences in bacterial cell walls to separate microorganisms into clear groups. Gram staining classifies bacteria as gram-positive or gram-negative. A heat-fixed bacterial smear is first stained with crystal violet, and iodine is added to...

special staining techniques

Bacterial Stains for Capsules, Spores, Flagella

Special bacterial stains help reveal capsule, endospore, and flagella structures that standard microscopy cannot show clearly. These stains improve how microbiologists identify bacteria and understand features linked to disease and classification. They are also useful in diagnosis and research because they expose key parts of bacterial cells. Capsule staining is a negative staining method that makes the capsule visible. A bacterial capsule is an outer layer that can act as a virulence factor,...

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key terms and concepts

Learn how Gram staining and acid-fast staining identify bacteria by cell wall structure, from crystal violet to carbolfuchsin, for diagnostics and treatment.

Gram and Acid-Fast Staining Methods | JoVE K12

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Weather and Climate

MS-ESS2-5

MS-ESS2-6

Minnesota Academic Standards in Science

Earth and Space Science

1.1.1 Earth’s Place in the Universe

3.1.1

4.2.2

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Earth's Place in the Universe

8-ESS1-3

Earth's Systems

6-ESS2-5

Earth and Human Activity

7-ESS3-5

8-ESS1-1

8-ESS1-2

6-ESS2-6

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Develop and use a model of the Earth-Sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the Sun and moon, and seasons. [Clarification Statement: Examples of models could include physical, graphical, or conceptual models.]

Develop and use a model to describe the role of gravity in the motions within galaxies and the solar system. [Clarification Statement: Emphasis for the model is on gravity as the force that holds together the solar system and Milky Way galaxy and controls orbital motions within them. Examples of models could include physical models (such as a model of the solar system scaled using various measures or computer visualizations of elliptical orbits) or conceptual models (such as mathematical proportions relative to the size of familiar objects such as students' school or state).] [Assessment Boundary: Assessment does not include Kepler's Laws of orbital motion or the apparent retrograde motion of the planets as viewed from Earth.]

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MS-ESS1-3

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MS-ESS1-4

Gram and Acid-Fast Staining Methods

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