Definition

1. Adjective:
   • Relating to bacteria that stain violet in Gram's method: Describes bacteria that retain the primary crystal violet stain during the Gram staining procedure, due to the thick peptidoglycan layer in their cell walls.

Usage

• Adjective:
  • This term is used to classify bacteria based on their cell wall structure and staining characteristics.
  • It is primarily used in scientific, medical, and microbiological contexts.

Examples

• Adjective:
  • Staphylococcus aureus is a common gram-positive bacterium.
  • The laboratory report identified the infection as being caused by a gram-positive coccus.
  • Penicillin is often effective against many gram-positive organisms.

Advanced Usage

• "Gram-positive cocci": A common phrase in microbiology specifying the shape (spherical) of the bacteria.
  • The blood culture grew gram-positive cocci in clusters.
• "Gram-positive rod": A phrase specifying a rod-shaped, gram-positive bacterium.
  • Bacillus anthracis is a gram-positive rod.

Variants and Related Words

• Gram-negative (adj): The contrasting category; bacteria that do not retain the crystal violet stain and instead take up a counterstain (appearing pink or red).
  • Escherichia coli is a gram-negative bacterium.
• Gram stain (n): The differential staining technique developed by Hans Christian Gram.
  • The Gram stain is a fundamental test in microbiology.

Synonyms

• There are no direct synonyms for this specific scientific classification. The term is precise and standard.

Related Phrases

• Gram reaction: The staining characteristic (positive or negative) of a bacterium.
  • The Gram reaction is the first step in bacterial identification.
• Gram-variable: Describing bacteria that stain inconsistently or show a mix of positive and negative reactions.
  • Some Actinomyces species can exhibit a gram-variable reaction.

Adjective

1. (of bacteria) being or relating to a bacterium that retains the violet stain used in Gram's method