STEP 236: Gram Stain: The Single Most Useful Procedure in Diagnostic Microbiology (CE: 0.5)


The Gram stain is the differential stain most used for direct microscopic examination of specimens and bacterial colonies because it has a broad-spectrum. This method was developed empirically by the Danish bacteriologist Christian Gram in 1884. This article discusses the gram stain, including its development, uses, and variations


Learning Objectives:

  • Outline Gram's method
  • Discuss variation in gram reactions
  • Identify gram stain modifications, recommended reagents, timing, and uses



Ricarte A. Gallarte, RM, MT


Launched: 2002