Hans Christian Gram is a 19th-20th century Danish bacteriologist noted for his development of the Gram stain. Born in Copenhagen on September 13, 1853, Hans Christian discovered a staining technique, which is used to identify and classify different types of bacteria. The technique is used till date even after a century.
Gram studied at the University of Copenhagen and was an assistant in botany. His study of plants introduced him to the fundamentals of pharmacology and the use of the microscope.
Gram entered medical school in 1878 and graduated in 1883. He traveled 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.
While treating a smear of bacteria with a crystal violet stain, followed by an iodine solution and organic solvent, he found differences in the structure and biochemical function of samples.
Gram’s findings were published in a journal in 1884, from where the terms Gram-positive and Gram-negative were coined.
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."
Gram's initial work concerned the study of red blood cells in men. He was among the first to recognize that macrocytes were characteristic of pernicious anemia.
Gram was appointed a professor of medicine at the University of Copenhagen in 1900. As a professor, he published four volumes of clinical lectures which became widely used in Denmark. He retired from the University of Copenhagen in 1923, and died in 1938.