Antibiotics, also called antibacterials, are a type of
antimicrobial drug used in
thetreatment and prevention of bacterial
infections. They may either kill or inhibit the
growth of bacteria. A limited number of antibiotics also possess
antiprotozoal activity. Antibiotics are not effective
against viruses such as the common cold or influenza, and
their inappropriate use allows the emergence of resistant organisms. In
1928, Alexander Fleming identified penicillin, the first chemical
compound with antibiotic properties. Fleming was working on a culture
of disease-causing bacteria when he noticed the spores of a little
green mold (Penicillium chrysogenum), in one of his culture plates.
He observed that the presence of the mold killed or prevented the growth of the
bacteria.
Sometimes the term antibiotic is used to refer to any
substance used against microbes, synonymous with antimicrobial,
leading to the widespread but incorrect belief that antibiotics can be used
against viruses. Some sources distinguish between antibacterial and
antibiotic; antibacterials are used in soaps and cleaners generally and
antibiotics are used as medicine.