Hans Christian Gram

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Hans Christian Gram
Born (1853-09-13)13 September 1853
Copenhagen
Died 14 November 1938(1938-11-14) (aged 85)
Copenhagen
Residence Denmark
Fields Bacteriology
Doctoral advisor Japetus Steenstrup

Hans Christian Joachim Gram (September 13, 1853 – November 14, 1938) was a Danish bacteriologist. He was the son of Frederik Terkel Julius Gram, a professor of jurisprudence, and Louise Christiane Roulund.

Gram studied botany at the University of Copenhagen and was an assistant in botany to the zoologist Japetus Steenstrup. His study of plants introduced him to the fundamentals of pharmacology and the use of the microscope.

He entered medical school in 1878 and graduated in 1883. He travelled throughout Europe between 1878 and 1885. In Berlin, in 1884, he developed a method for distinguishing between two major classes of bacteria. This technique, the Gram stain, continues to be a standard procedure in medical microbiology.

In 1891, Gram became a lecturer in pharmacology, and later that year was appointed professor at the University of Copenhagen. In 1900 he resigned his chair in pharmacology to become professor of medicine.

Gram stain[edit]

Main article: Gram staining

The work that gained him international reputation was his development of a method of staining bacteria, to make them more visible under a microscope. The stain later played a major role in classifying bacteria. Gram was a modest man, and in his initial publication he remarked, "I have therefore published the method, although I am aware that as yet it is very defective and imperfect; but it is hoped that also in the hands of other investigators it will turn out to be useful." A Gram stain is made using a primary stain of crystal violet and a counterstain of safranin. Bacteria that turn purple when stained are called 'Gram positive', while those that turn red when counterstained are called 'Gram negative'.

Other work[edit]

His initial work concerned the study of Red blood cells in men. He was among the first to recognise that macrocytes were characteristic of pernicious anaemia.

After his appointment as professor of medicine in 1900 he published four volumes of clinical lectures which became widely used in Denmark. He retired in 1923.

References[edit]