"My only merit is that I did not discard the cultures at an early stage."

"I am often asked if I foresaw the impact of penicillin. My honest answer is no."

"I am only one of many who have contributed to the development of penicillin."

"I certainly did not plan to revolutionise all medicine by discovering the world's first antibiotic, or killer of bacteria. But I suppose that is exactly what I did."

"The mere fact that a substance has bactericidal powers does not mean that it can be used for the treatment of septic infections."