Antimicrobial resistance. Already explained in 1945.

ALEXANDER FLEMING- Penicillin- Nobel Lecture, December 11, 1945

I am going to tell you about the early days of penicillin, for this is the part
of the penicillin story which earned me a Nobel Award. I have been frequently asked why I invented the name "Penicillin". I simply followed perfectly orthodox lines and coined a word which explained that the substance penicillin was derived from a plant of the genus Penicillium just as many years ago the word "Digitalin" was invented for a substance derived from the plant Digitalis. To my generation of bacteriologists the inhibition of one microbe by another was commonplace. We were all taught about these
inhibitions and indeed it is seldom that an observant clinical bacteriologist
can pass a week without seeing in the course of his ordinary work very definite instances of bacterial antagonism.

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