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Home > Be Healthy > Health Library > Gram stain
A Gram stain is a type of test that helps tell whether bacteria causing an infection are Gram-positive or Gram-negative. This can help a doctor choose the best treatment for an infection.
The Gram stain is done by putting a special dye on the bacterial cells. Gram-positive bacteria retain the dye and turn a different color than Gram-negative bacteria do. Sometimes more testing is done after the Gram stain to identify the specific kind of bacteria and the antibiotics that can kill them.
Current as of: June 17, 2021
Author: Healthwise Staff
Medical Review:Kathleen Romito MD - Family Medicine & Adam Husney MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Martin J. Gabica MD - Family Medicine
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