Penicillin is a really strong drug that is used to treat an infection that is caused by bacteria. It was the first antibiotic that successfully treated serious diseases in human beings. It was discovered in 1928 by Sir Alexander Fleming. Since it was used widely, many forms of this drug were being manufactured in the 1940s. It was used to treat pneumonia, rheumatic fever, scarlet fever, and many other diseases. The Penicillin works by preventing the formation of the stiff cell walls that the bacteria needs to survive. Fleming discovered this drug when he saw mold growing on a lab dish that contained common bacteria. Penicillin can be taken by mouth, but it's more useful by injection. The first patient that was treated with Penicillin was a police officer. The policeman had blood poisoning, and he began to recover by using the Penicillin, but later died because the hospital lacked a sufficient supply of the Penicillin