In 1945, at the end of World War II, Professor Sir Alexander Fleming (as he had then become) was asked by Butterworth, the medical publishers, to write a book on penicillin. He refused, on the grounds that he was too busy and that as a laboratory worker, he would have been unable to place penicillin therapy in a proper perspective in relation to other forms of medical and surgical treatment. However, he did agree to edit a book-and produced a volume (Fleming, 1946a) which is now something of a rarity-bringing together contributions from many of those who had gained experience of the compound during its early years of scarcity. Furthermore, he wrote an introductory chapter in which he overcame his modesty and set out some general rules for penicillin treatment (Fleming, 1946b). First, he wrote, it should be used only for the treatment of those infections caused by penicillin-sensitive microbes. His list of these runs: staphylococci, Streptococcus pyogenes, Streptococcus viridans, some anaerobic streptococci, pneumococcus, gonococcus, meningococcus, and so on. He also points out the importance of acquired resistance even though there was little of it at the time. However, despite the many casualties on this list, the principle remains sound. Second, the antibiotic must be given by an appropriate route, in adequate dosage, for an appropriate period of time-and despite uncertainties, the principles again remain true. En passant,