Glossary definition of Gram Stain

///Glossary definition of Gram Stain
Glossary definition of %s2017-09-18T17:16:03+00:00

Definition of Gram Stain

Gram Stain - A differential staining technique in which cells either stain pink (gram-negative) or purple (gram-positive) depending upon their structural type.

During a gram stain, a bacterial sample is smeared on a microscope slide and allowed to dry. The slide is then stained with a violet dye, treated with acetone-alcohol (a decoloriser) and finally counter-stained with a red dye.

Gram-positive bacteria retain the first violet dye as they have a thick layer of peptidoglycan in their cell walls creating cells which appear violet.

In gram-negative bacteria, the acetone-alcohol washes out the violet dye and the counter-stain is taken up creating cells which appear red. The cell walls of gram-negative bacteria have an outer layer of lipoprotein overlaying a thin layer of peptidoglycan.

Example process:

  • slide stained with crystal violet (1 min),
  • rinsed with water,
  • stained with iodine (1 min),
  • rinsed with water,
  • destained with acetyl-choline,
  • rinsed with water,
  • counterstained with safranin (1 min)

Ames

Antibiotic Resistance

Antibiotics

Antimicrobial Agent

Antimicrobial Drug Resistance

Antimicrobial Susceptibility Testing (AST)

Bacillus

Bacteria

Bioburden

CFU

Chromogenic media

CLSI

Coccus

Conjugation

Endospore

Enteric Bacteria

EUCAST

Flagellum

Fungi

Gram Stain

Membrane filtration

MIC

Microbiology

Microorganism

Morphology

OPKA

Pathogen

Penicillins

Plasmid

SBA

Spirillum

Spirochaete

SRID – Single Radial Immunodiffusion

Sterility test

Vaccine

Vibrio

Virus

ProductsWhere to buySupport