They are all still produced, by mold slime, ie naturally : and this will probably always be so.
They are produced almost as bulk chemicals, thousands of tons worth annually, a multi-billion dollar industry that lies at the very foundations of the multi-trillion dollar health industry.
But there is (and was) no international treaty, closely negotiated at the very top level (Lord Halifax and Dean Acheson) , at the height of total war and over an extended period of two years, on the patents and scientific information involved in this crucial production of natural penicillin.
Instead another - exceedingly rare - international treaty was negotiated by the wartime American government --- a nation historically very loath to sign any sort of international treaty.
It focused exclusively on the post-war perfection of what had been - at one time - intended to be a timely wartime secret weapon of war : that elusive and illusionary phantom known as synthetic penicillin.
So it was that if between 1943 and 1946, a individual scientist had increased the amount of penicillin retained from the initial crude penicillin medium from 50% to 100% on first purification run through, she or he would have been classed be a war-hero and covered under this Acheson-Halifax Treaty, via its clause on the purification of penicillin.
(Even if success in this case might merely mean that the scientist retained 2 units of semi-purified penicillin per 2 units of initial crude penicillin rather than just the normal 1unit semi-refined from 2 units of initial crude penicillin.)
But if a scientist or firm increased the production of crude penicillin from the 2 crude units per ml of starting medium (as was common in the first 14 years of penicillin production) to 80,000 units of crude penicillin per ml of starting medium (as is common today) , they won't be considered important enough to be covered under this treaty !
It was this loophole that allowed a small soda pop supplier to become, in time, the biggest drug company in the world.
This was when Pfizer incredibly rapidly increased its production of natural penicillin from 2 units over 14 days to 2000 units over 4 days, per ml of starting medium ---- down right under the noses of the treaty negotiators.
As a result, 90% of the penicillin that landed on the D-Day beaches came from this one firm alone - making its world wide reputation over night.
That was because Pfizer's John L Smith, alone among his industry's CEOs, decided to make upping the production levels of natural penicillin his Job One, rather than going full out on synthesizing artificial penicillin and giving just lip service to public claims to be making more natural penicillin for the dying.
10% of nothing is ..... still nothing !!
When a CUPE local for mental health orderlies and support staff went on strike here in Nova Scotia, I was no longer a mental health employee or union local member but I did devise the winning strike slogan : "Ten Percent of Nothing is Still Nothing !".
The government had told the public these ungrateful employees were getting a hefty 10% pay raise out of your tax dollars : but we came back with the fact some of the employees were earning less than the government's own, mandated by law, legal minimum wage !
Two units of penicillin per ml of starting medium is nothing, for such a lot of time, care and expense. Retaining 100% of it , instead of 50% of it , is still nothing.
The penicillin we use today is exceedingly cheap and abundant : because even if retaining only 50% of the 80,000 units per ml yield it is indeed still a very, very, very, big something....