Gram stain

From IDWiki

Procedure

  • Fix to slide with heat or methanol
  • Add crystal violet, and wait 60 seconds
  • Wash with water then flood with iodine, and wait 60 seconds
  • Wash with water then decolorize with 95% ethanol or acetone
  • Counter-stain with safrinin, wait 30 seconds then wash off with water

Interpretation

  • Gram-positive = blue
  • Gram-negative = red
  • Peptidoglycan layer (cell wall) is thick with extensive cross-linking in gram-positive