Richard Friedrich Johannes Pfeiffer

Richard Pfeiffer was a German physician and bacteriologist, born in 1858 in the Province of Posen, who trained as a military doctor in Berlin and became one of Robert Koch's closest assistants at the Institute of Hygiene. In 1892 he isolated a rod-shaped bacterium from influenza patients and named it Bacillus influenzae, later called Haemophilus influenzae; it was long thought to cause influenza, a view overturned after the 1918 pandemic. In 1894 he described the bacteriolysis of cholera bacteria in immunised guinea pigs, known as the Pfeiffer phenomenon and now understood as complement-mediated lysis. He developed the concept of endotoxin as a heat-stable bacterial poison and was a pioneer of typhoid vaccination. He served on the plague commission sent to India in 1897, fell ill with plague himself after an accident, and later held the chair of hygiene at Königsberg and then at Breslau, where he retired in 1925. He died in 1945.