Gram Staining Method

**Semantic type:** Laboratory Procedure

**Definition:** This is a method (named after the Danish bacteriologist, Hans Christian Gram) for staining and identifying bacteria. It is based on the differential retention of a crystal violet-iodine complex within the cell membrane. Gram-positive organisms will appear blue-black or purple while Gram-negative organisms will appear red.

**Synonyms:** - GRAM STAIN - Gram Staining