A particular group of these agents is made up of drugs called antibiotics, from the Greek word anti (“against”) and (“life”). Some antibiotics are produced from living organisms such as bacteria, fungi, and molds. Others are wholly or in part synthetic—that is, produced artificially. Penicillin is one of the best-known antibiotics. Its discovery and later development is among mankind’s greatest achievements.
Invention of antibiotics has enabled the medical profession to treat many infectious diseases effectively, including some that were once life threatening. Antibiotics can be bacteriostatic (bacteria stopped from multiplying) or bactericidal (bacteria killed). It is believed that antibiotics interfere with the surface of bacteria cells, causing a change in their ability to reproduce. To work against infecting organisms, an antibiotic can be applied externally, such as to a cut on the skin’s surface, or internally, reaching the bloodstream within the body.