WHY STAIN BACTERIA?
	Under the microscope bacteria are very hard to see. The cell wall of bacteria can easily be stained making them easily viewed.
WHAT IS A GRAM STAIN?
	A Danish physician Dr. Gram developed a staining method which would stain some bacteria blue (Gram +) and others red (Gram -). The color differences are due to the ability of the cell wall to retain a certain color.
	WHY GRAM STAIN?
	To diagnose a disease you first identify the shape of the bacteria. Next is to Gram stain. By knowing a bacteria is a Gram (+) cocci or a Gram (-) bacilli the Doctor has a valuable tool in diagnosing and choosing a treatment for a bacterial disease.	Image courtesy of Environmental Mutagen Society Newsletter

Smear Procedure

Staining Procedure

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Last updated: 08/07/03