Near this site in 1928, penicillin, the first antibiotic to be truly successful in treating bacterial infections, was discovered by physician Alexander Fleming in a small laboratory at St. Mary’s Hospital, London, England. Most living humans have been treated with antibiotics since early childhood, and you may have survived to read this marker because of this discovery that came about partly by accident. Fleming’s interest in antibiotics began with a desire to find an alternative to the use of antiseptics for treatment of infections. Fleming argued with his mentor Sir Almroth Wright that antiseptics harm the human immune system. This thinking led to Fleming’s discovery in 1922 of lysozymes, enzymes that cause bacteria to lyse. Lysozymes, however, were effective only against bacteria that were not highly infectious. In 1928, Fleming returned to his laboratory after a vacation and found that some of his Petri plates inoculated with Staphylococcus aureus bacteria had been contaminated by a fungus. He noted a transparent area around the fungal growth and correctly hypothesized that a substance produced by the fungus was killing the bacterial cells. He identified the fungus as Penicillium notatum (now known as Penicillium chrysogenum) and named the antibiotic penicillin. Fleming's observations were published in 1929 in the British Journal of Experimental Pathology with little interest in the work. Fleming then attempted unsuccessfully to refine and produce penicillin in larger amounts. In 1938, Howard Florey, a pathology researcher, and Ernst Chain, a cancer researcher, came across Fleming’s decade-old work on penicillin while searching for articles on lysozymes. World War II was the impetus for renewed interest in the development of methods for refinement and mass production of penicillin, and the drug was first widely used during that war. The three researchers were awarded the 1945 Nobel Prize in Physiology or Medicine for their part in the discovery. 

--A. Sharma