gram-negative
/'græm'negətiv/
Học thuậtThân thiện
Definition
- Adjective:
- Relating to a classification of bacteria: Describes bacteria that do not retain the crystal violet stain used in the Gram staining method, a common laboratory test. These bacteria appear pink or red under a microscope after the staining procedure.
Usage
- The term is primarily used in scientific, medical, and microbiological contexts to classify and describe bacterial species based on their cell wall structure.
- It is typically hyphenated when used as a compound adjective before a noun (e.g., gram-negative bacteria). It can also be used after a linking verb (e.g., The organism is gram-negative).
Examples
- Adjective:
- E. coli is a gram-negative bacterium commonly found in the intestines.
- The laboratory report confirmed the infection was caused by a gram-negative rod.
- This antibiotic is particularly effective against gram-negative organisms.
Advanced Usage
- "Gram-negative" is part of a fundamental binary classification system in bacteriology, contrasting with "gram-positive." The difference is crucial for diagnosis and treatment, as the cell wall structure affects antibiotic susceptibility.
- The term is named after Hans Christian Gram, the Danish bacteriologist who developed the staining technique. It is often capitalized as Gram-negative, though the lowercase form is also widely accepted.
Variants and Related Words
- Gram-positive (adj): Describing bacteria that retain the crystal violet stain and appear purple under a microscope.
- Staphylococcus aureus is a gram-positive coccus.
- Gram stain (n): The differential staining technique used to classify bacteria as gram-positive or gram-negative.
- The doctor ordered a Gram stain of the sputum sample.
Synonyms
- There are no direct synonyms for this specific technical classification. Descriptive phrases could include "bacteria that do not retain crystal violet stain" or "pink-staining bacteria," but these are explanations, not synonyms.
Related Phrases
- Gram-negative sepsis: A serious, systemic infection caused by gram-negative bacteria.
- The patient was admitted to the ICU with suspected gram-negative sepsis.
- Gram-negative bacilli: A common morphological description for rod-shaped gram-negative bacteria.
- The culture grew a gram-negative bacilli.
Related Idioms
- There are no common idioms using the term gram-negative.
Adjective
- (of bacteria) being of or relating to a bacterium that does not retain the violet stain used in Gram's method