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 and subsequently concentrated what he later named "penicillin". During the next twelve years, Fleming grew and distributed the original mold, which was eventually identified as "Penicillium notatum" (now known as "Penicillium chrysogenum"). He was unsuccessful in making a stable form of it for mass production. Cecil George Paine, a pathologist at the Royal Infirmary in Sheffield, attempted to treat sycosis (eruptions in beard follicles) with penicillin but was unsuccessful, probably because the drug did not penetrate deep enough. Moving on to ophthalmia neonatorum, a gonococcal infection in babies, he achieved the first cure on 25 November 1930. He cured four