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
Penicillin "Penicillium" mould. Fleming asked C. J. La Touche to help identify the mould, which he incorrectly identified as "Penicillium rubrum" (later corrected by Charles Thom). He expressed initial optimism that penicillin would be a useful disinfectant, because of its high potency and minimal toxicity in comparison to antiseptics of the day, and noted its laboratory value in the isolation of "Bacillus influenzae" (now called "Haemophilus influenzae"). Fleming was a famously poor communicator and orator, which meant his findings were not initially given much attention. He was unable to convince a chemist to help him extract and stabilize the antibacterial compound