Antibiotics play a major role in the field of medicine today and penicillin has been recognized as one of the greatest advances in therapeutic medicine. Who could have imagined that something we use today on a regular basis in hospitals, clinics, and private offices was discovered by chance? In September 1928, penicillin was discovered by Sir Alexander Fleming, a professor of bacteriology in London. It all started when Fleming returned from a vacation with his family and went through stacks of Petri dishes. While he was cleaning and getting rid of the contaminated dishes, he found that a mold had developed on an accidentally contaminated staphylococcus culture plate. Upon examination of the mold, he noticed that the culture prevented the growth of staphylococci. In the past, hospitals were full of people with blood poisoning contracted from a cut or a scratch and doctors could do little for them but wait and hope. After the introduction of penicillin in the 1940s, it has changed the course of medicine and penicillin is now the most widely used antibiotic in the world. It has enabled physicians to treat formerly severe and life-threatening illnesses such as meningitis, gonorrhea and syphilis. Over the years, there have been many more antibiotics discovered but penicillin is still the antibiotic of choice when dealing with bacterial infections. Without Sir Alexander Fleming and his discovery, the medical world as we know it today would prove to be much different.