"I have been accused of being untidy. I confess to being untidy, but I have never allowed my untidiness to interfere with my work."

"I have always been interested in the effect of one microbe on another."

"The public will not understand the dangers of using penicillin indiscriminately."

"It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them, and the same thing has occasionally happened in the body."

"I am very grateful for the recognition I have received, but the real credit belongs to the mould."