text: Penicillin does not contain aspirin. The American Heritage Dictionary on Yahoo! defines penicillin as "Any of a group of broad-spectrum antibiotic drugs obtained from penicillium molds or produced synthetically, most active against gram-positive bacteria and used in the treatment of various infections and diseases." Penicillin also contains the chemical probenecid to assist with its retention by the body.\n\nIt was originally derived from Penicillium notatum and Scottish scientist Alexander Fleming discovered it. A team led by Howard Florey and Ernest Boris Chain would develop it into a commercial drug. This work led to Fleming, Florey and Chain winning the Nobel Prize for medicine in 1945.