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## Antiseptics and Disinfectants ### Differences between Antiseptics and Disinfectants | | Antiseptics | Disinfectants | |---|---|---| | | Mild germ-killing chemicals. | Strong germ-killing substances. | | | Cause no harm to skin and body. | May cause harm to skin and body. | | | Applied on bo...

## Antiseptics and Disinfectants ### Differences between Antiseptics and Disinfectants | | Antiseptics | Disinfectants | |---|---|---| | | Mild germ-killing chemicals. | Strong germ-killing substances. | | | Cause no harm to skin and body. | May cause harm to skin and body. | | | Applied on body. | Applied on spots | | | Example: Iodine | Example: Phenol | ## Antibiotics **Antibiotics** are chemical substances produced by some microorganisms that can kill or inhibit the growth of other microorganisms. ### The Term Antibiotics - The first antibiotic, Penicillin, was discovered in 1929, but its first use for treating any human disease was tried in the 1940s. - The term “Antibiotics” for such a category of drugs was coined much later by Selman Waksman in 1942. ### Discovery of Penicillin - Alexander Fleming (1881-1955) was working in a hospital in London growing laboratory cultures of the bacterium *Staphylococcus* (round bacteria growing in clusters). - In 1928, he found that a certain unwanted mould, *Penicillium*, had grown in one of the cultures in a petri dish, and this had inhibited the growth of the bacteria for some distance. - Obviously, some substance must have spread from the mould, which killed the bacteria up to that distance. - Fleming named this bacteria-killing substance released from the mould as Penicillin in 1929. - In the expectation of this substance to become an effective killer of disease-causing bacteria, it was tried on laboratory animals and showed positive results without harming the animals. - On humans, the substance penicillin was first tried in the early 1940s and was found to be quite effective against several infections. - In particular, it yielded very good results in treating gonorrhea, a sexually transmitted disease (STD). ### Sources of Antibiotics * The mould which produced penicillin in Fleming’s findings was *Pencillium notatum*. * This mould is somewhat similar to the one that often grows on oranges, lemons, and other citrus fruits. * The commercial production of penicillin has been largely done from a related species *P. chrysogenum*, but it is also being produced synthetically. * Streptomycin is one of the very widely used antibiotics. This is obtained from a bacterium *Streptomyces*. * A large number of antibiotics are now made synthetically rather than from culturing microorganisms. ### Uses of Antibiotics 1. Primarily, the antibiotics find a wide used in medicine to fight infections. 2. Certain antibiotics are used as food preservatives, especially fresh meat and fish. 3. Some are used in treating animal feed to prevent internal infections. 4. Some antibiotics are used for controlling plant pathogens.