NCIt 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.;
Alternative definition : CDISC: A microscopy staining method for staining and identifying bacteria, 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.;