Benzylpenicillin of penicillin allergy. Use during pregnancy is generally safe. It is in the penicillin and β-lactam class of medications. Benzylpenicillin was discovered in 1929 by Alexander Fleming and came into commercial use in 1942. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about US$0.24–2.72 per day. In the United States a course of treatment costs $100–200. As an antibiotic, benzylpenicillin is noted to possess effectiveness mainly against Gram-positive organisms. Some Gram-negative organisms such as "Neisseria gonorrhoeae" and "Leptospira
History of penicillin patients (one adult, the others infants) of eye infections, although a fifth patient was not so lucky. At Oxford, Howard Walter Florey organized a large and very skilled biochemical research team, notable among them Ernst Boris Chain and Norman Heatley, to undertake clinical trials and produce a stable penicillin in quantity. In 1940, Chain and Edward Abraham reported the first indication of antibiotic resistance to penicillin, an "E. coli" strain that produced the penicillinase enzyme, which was capable of breaking down penicillin and completely negating its antibacterial effect. Between 1941 and 1943, Moyer, Coghill and Raper at the USDA Northern