Alexander Fleming is credited with the accidental discovery of penicillin in which year?

• A. 1939
• B. 1905
• C. 1928
• D. 1941

Answer: (C)

Penicillin was discovered when Fleming noticed that a mold contaminating a Staphylococcus culture had inhibited bacterial growth around it. The mold, later identified as Penicillium, released a substance into the surrounding medium that prevented the bacteria from growing, creating a clear area known as a zone of inhibition. From this observation, Fleming identified the mold’s product as having antibacterial properties and named it penicillin. This key observation occurred in 1928, marking the year of discovery. Later work by other scientists during the 1940s purified penicillin and enabled large-scale production for clinical use. The other dates are related to later developments or unrelated aspects, not the initial discovery itself.