Penicillin was not doing anything useful throughout the 1930s ( like being injected into dying patients), but it was not exactly unknown in many areas of science : biochemistry, botany and mycology, general medicine, microbiology , pharmaceuticals.
I have sufficient articles and references from that time period to notice a very interesting pattern, I believe, in terminology.
Penicillin is frequently described as "the" substance described by "Fleming", not "a" substance described by "Alexander Fleming, the British bacteriologist."
It is almost as if the audience is expected to have already heard of penicillin - as something in the air.
Fleming did get about a lot, was a great gossip and an avid attender of meetings and conferences.
And he always seemed to manage to mention penicillin in these corridor gossip sessions.
All this happened, of course, in a very big national medical and scientific centre and in fact in a central hub and way station of world-wide medical research and science generally.
Europeans or Americans on route to each other, often passed through 1930s London, en route, as they still do today.
And of course, London-originated journals (like Nature and Lancet) had virtually 100% circulation coverage in every part of the world claiming to be a credible place of research.
So in 1937, it seemed natural that the powers to be at the big American drug company, Squibb, asked a staffer to do a literature search and assessment of this penicillin substance.
This was before sulfa had really hit its stride and well before Dubos has produced the (toxic but effective) antibiotic gramacidin.
And the fact that penicillin had enough articles on it to make a literature search worth while again shows it was taken seriously across many sectors of medicine and science.
But, I believe, Fleming's damming personal - if off the record - assessment that it was totally useless for systemic use hindered casual investigators taking it seriously.
But what penicillin needed was someone who only read the evidence in Fleming's original 1929 article and saw something in the evidence that no one else saw and got passionate about penicillin's possibilities for systemic use.
Someone who never heard Fleming put down systemic penicillin or had heard him many times and as a result had dismissed , generally, as a bit of a old fool.
Perhaps, someone like Martin Henry Dawson....