Shibasaburo Kitasato procured a job at the Japanese Home Ministry's Health Department after graduating from Tokyo Medical School. During the work, he received orders to travel to Germany, where he would work under physician Robert Koch, one of the founders of modern bacteriology. It was there that Kitasato succeeded in obtaining the world's first pure culture of the tetanus bacteria. He also demonstrated immunity could be achieved with a serum containing an antitoxin, inventing what is now known as "serum therapy".
The Home Ministry was pressing ahead with plans to build a national institute of infectious diseases, but Kitasato found that it would take a long time for the approval of the establishing institutions after his return. While he was devastated, Fukuzawa pledged his support for a private institute and established the Institute for Study of Infectious Diseases directed by Kitasato in the same year. Thus began Kitasato's friendship with the fifty-seven-year-old Fukuzawa, who would become his lifelong mentor.
By commemoration of the 60th anniversary, the discussion to establish a new department was made in Keio University, and Kitasato served as the first Dean of the Department of Medicine (later the School of Medicine) in 1917. Moreover, he was appointed as the first Director General of Keio University Hospital in 1920,and he advocated for“close cooperation between basic and clinical sciences.”Since then, we have been engaged in education, medical care and research under his spirit.