Robert Koch

Robert Koch was a German physician working privately when he isolated the anthrax bacterium in 1876, an event now marked as the birth of modern bacteriology. He developed the bacterial culture method using agar and glass plates, invented oil immersion microscopy, and became the first to grow bacteria in controlled laboratory conditions. In 1882 he announced his discovery of the tuberculosis bacterium - a date the World Health Organization has observed as World Tuberculosis Day since 1982 - and later identified the cholera agent, work that won him the 1905 Nobel Prize in Physiology or Medicine. His framework for linking specific pathogens to specific diseases, known as Koch's postulates, set the scientific foundation for public health and remains in use today. A major misstep came when he promoted tuberculin as a tuberculosis cure; it failed as treatment but later proved useful for diagnosis. He rose from private practice to director of Berlin's Royal Prussian Institute for Infectious Diseases, now named in his memory.