Penicillin powder in screw top bottle with label, unsigned, Oxford, England, 1942

Some of the earliest clinical trials of penicillin took place in Oxford, England, in early 1942. At first supplies were very limited. It is believed that this sample was recovered from the urine of patients treated with the antibiotic. Once clinical trials proved successful, penicillin was used for a wide range of infections and stimulated research into other antibiotics.