AAT Bioquest

What are the differences between traditional vs modern Gram staining?

Posted December 10, 2019


The Gram stain was introduced in 1884. In the intervening 140+ years, there have been multiple adaptations in response to scientific needs. Traditional Gram staining-the procedure traditionally used as the core of microbiological taxonomy-is an inexpensive but labor-intensive 5-step staining process. It categorizes bacteria into one of two major categories, Gram-positive or Gram-negative, according to the structure of the cell wall. The modernized procedures are shorter and employ less destructive methods, allowing for further characterization of treated bacterial cells. For a direct comparison of original and updated experimental techniques, see Table 1 below:


Table 1. Comparison of Traditional and Modern Gram Staining
 Traditional Gram StainModern Gram Stain
Fixation RequiredYesNo
Number of Steps53
Detection TypeColorimetricFluorimetric


The use of traditional or modernized Gram stain procedures is decided based on current experimental needs and the resources available. Researchers seeking to verify or compare to older publications might be best served by traditional methodology. Newer techniques are more efficient and may be suited to time-sensitive experiments or those with minimal personnel. 


Additional resources

MycoLight™ Rapid Fluorescence Bacterial Gram Stain Kit