Penicillin

Penicillin is an antibiotic obtained from Penicillium moulds and were among the first medications to be effective against many bacterial infections caused by staphylococci and streptococci.

Penicillin was discovered in 1928 by Scottish scientist Alexander Fleming, for which he shared the 1945 Nobel Prize in Physiology or Medicine with Florey and Chain. Penicillin was discovered almost by accident. Returning from holiday, Fleming removed the tops from some old petri dishes and noticed that the bacteria he had grown were being killed by a mould - penicillin. He used the word antibiotic to describe penicillin. However, Fleming did not have the money or the facilities to continue his research. In the late 1930s two Oxford scientists, Ernst Chain and Howard Florey took up the challenge and were given extra government funding. The rest was history as they say. By 1943, penicillin was being mass produced and was effective in the war. In 1945 the US army was giving two million doses per month.

The discovery of penicillin was a major medical breakthrough. It is now the most widely used antibiotic in the world and allows doctors to treat formerly severe and life-threatening illnesses such as bacterial endocarditis, meningitis, pneumococcal pneumonia, gonorrhea and syphilis.

Bacterial infection, as a cause of death, plummeted. Between 1944 and 1972 human life expectancy jumped by eight years - an increase largely credited to the introduction of antibiotics. It led to a euphoria with people talking about the end of infectious diseases. However Fleming himself warned: "The greatest possibility of evil in self-medication is the use of too small doses so that instead of clearing up infection the microbes are educated to resist penicillin and a host of penicillin-fast organisms is bred out which can be passed to other individuals and from them to others until they reach someone who gets a septicaemia or pneumonia which penicillin cannot save." In the decades after, his warning came true with the emergence of resistant bacteria.

Resistance has now emerged for all known antibiotics in use. For most antibiotics, and classes of antibiotics, antibiotic resistant genes have also entered the bacterial population in the domains where antibiotics are used (for example in hospitals, farms and aqua-culture ponds).