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Back to Previous Page APUA: Alliance for the Prudent Use of Antibioticshttp://www.apua.org |
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About
bacteria & antibiotics
Bacteria (singular: bacterium) are single-celled microscopic organisms that often live together in colonies. There are numerous types of bacteria. Most are harmless and some are even helpful, by aiding digestion or breaking down rotting material. A few bacteria can cause diseases in humans, animals and plants; these are referred to as pathogenic bacteria or pathogens. Where do bacteria live? Excepting normally sterile sites such as the blood stream and spinal fluid, bacteria are commonly found almost anywhere. Their natural habitats are soil, plants, water, and on the skin and in the digestive tracts of humans and animals. They may survive for varying amounts of time on other surfaces that have had contact with these environments. What is an antibiotic? An antibiotic is a chemical compound that can kill or inhibit the growth of a bacteria without causing the host (such as a human or an animal) significant damage. Antibiotics can be naturally produced (like penicillin) by a mold or bacterium, or synthetically made (like the fluoroquinolones). How do antibiotics work? The activity of antibiotics may be classified as "bacteriostatic" or "bacteriocidal." Bacteriostatic drugs stop the cells from growing and multiplying, but do not actually kill them. This inhibition of growth allows time for the infected host to mount an immune response and eliminate the non-growing infectious agent. Bacteriocidal drugs actually kill the bacteria. These drugs are the preferred choice when a person's immune system is weakened and incapable of destroying the organism itself. In either case, the antibiotics act by disrupting bacterial cell activity, for example, by attacking the outer bacterial cell wall or its inner membrane, or the chemical pathways necessary for the bacteria to live and reproduce. Antibiotics have no activity against viruses.  How are antibiotics used? Antibiotics are used in human and veterinary medicine to treat illnesses caused by bacteria and, in some cases, to prevent bacterial infections (prior to surgery, for example). Antibiotics are also used to increase growth in certain food animals, and are used as pesticides to control bacterial infections in food crops. How many antibiotics are there? There are hundreds of antibiotics, most of which belong to eight major family groups. The drugs are classified according to their basic chemical structure. Most of the members within a family arise from additions or substitutions of attachments to the drug's core structure. (See the Table of Antibiotics.) Next Q&A: About antibiotic resistance |
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