it is toxic to experimental animals and can kill highly resistant pathogens. There were no biochemists at St. Mary’s hospital, so it was not possible to isolate penicillin in an injectable form. This work was carried out in Oxford by H. W. Flory and E. B. Cheyne only in 1938. Penicillin would have sunk into oblivion if A. Fleming had not previously discovered lysozyme (here it really came in handy!).
It was this discovery that prompted Oxford scientists to study the medicinal properties of penicillin, as a result of which the drug was isolated in pure form in the form of benzylpenicillin and tested clinically. Even the very first studies of A. Fleming gave a number of invaluable information about penicillin. He wrote that it is “an effective antibacterial substance that has a pronounced effect on pyogenic (i.e., causing the formation of pus) cocci and sticks of the diphtheria group. Penicillin, even in large doses, is not toxic to animals. It can be assumed that it will be an effective antiseptic for external treatment of areas affected by penicillin-sensitive microbes, or when it is administered internally.”