“The man behind the Gram Stain”

Those who work in diagnostic bacteriology labs will hear his name mentioned every day, probably several times, but how many of us know about where the name “Gram” came from?

"An over-decolourised Gram."
“An over-decolourised Gram.”

Hans Christian Gram was born in 1853 in Denmark. He initially studied Botany, then in 1883 he graduated from medical school and settled in Berlin. In 1884, he noticed that certain stains were preferentially taken up by bacteria from post mortem lung tissue samples. He used crystal violet as the initial stain and fixed the stain with potassium tri-iodide (Lugol’s solution). After this he used ethanol to wash the stain away. He did this with both Streptococcus pneumoniae and Klebsiella pneumoniae bacteria, observing that Streptococcus pneumoniae retained the stain after washing with alcohol (Gram positive) whereas Klebsiella pneumoniae did not. (Gram negative)

Hans Christian Gram only invented the first three parts of the Gram stain. The fourth part, counterstaining with safranin (or similar), did not happen for another few years, and was probably introduced by a German pathologist, Carl Weigert.

Hans Christian Gram never received the Nobel prize for his discovery, but received numerous other awards. He went on to become Professor of Medicine at the University of Copenhagen. His other main discovery was the link between macrocytic red cells and pernicious anaemia.

He died in 1938.

For a really nice article on Hans Christian Gram’s life and also the mechanism of action of the Gram stain along with it’s limitations, click here.

It is actually quite extraordinary that a method invented 130 years ago is still a mainstay of diagnostic microbiology today. Personally I think it’s really important that we know a little about the history behind the microbiology methods we currently use. It just adds that extra little bit of meaning to them….



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