Penicillin nontoxic in humans by first performing toxicity tests in animals and then on humans. His subsequent experiments on penicillin's response to heat and pH allowed Fleming to increase the stability of the compound. The one test that modern scientists would find missing from his work was the test of penicillin on an infected animal, the results of which would likely have sparked great interest in penicillin and sped its development by almost a decade. The importance of his work has been recognized by the placement of an International Historic Chemical Landmark at the Alexander Fleming Laboratory Museum in London on
History of penicillin patients (one adult, the others infants) of eye infections, although a fifth patient was not so lucky. At Oxford, Howard Walter Florey organized a large and very skilled biochemical research team, notable among them Ernst Boris Chain and Norman Heatley, to undertake clinical trials and produce a stable penicillin in quantity. In 1940, Chain and Edward Abraham reported the first indication of antibiotic resistance to penicillin, an "E. coli" strain that produced the penicillinase enzyme, which was capable of breaking down penicillin and completely negating its antibacterial effect. Between 1941 and 1943, Moyer, Coghill and Raper at the USDA Northern