Lab method
Gram stain
First-pass bacterial sorting tool
gram stayn
High-yield clue
Color + shape + arrangement gives the first branch in many ID questions.
Overview
A differential staining concept used to sort bacteria by cell-wall staining behavior and morphology before more specific testing.
Classification
- Differential stain
- Cell-wall concept
- Foundational lab workflow
Lab & identification clues
- Gram-positive: purple in classic teaching
- Gram-negative: pink/red in classic teaching
- Pair with cocci/rods/arrangement
Associations
- Bacterial classification
- Empirical teaching frameworks
- ID flowcharts
Commonly confused with
- Acid-fast stain
- Simple stain
Your notes
Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.