An antibiotic is a substance produced by or derived from a microorganism (especially mold) that destroys or inhibits the growth of other microorganisms. Antibiotics are used to treat infections caused by organisms that are sensitive to them usually bacteria or fungi. An antibiotic is a selective poison. It has been chosen so that it will kill the desired bacteria but not the cells in your body.

Antibiotics stop or interfere with a number of everyday cellular processes that bacteria rely on for growth and survival such as crippling production of the bacterial cell wall that protects the cell from the external environment.

Each different type of antibiotic affects different bacteria in different ways. A typical use for antibiotics is an ear infection which can be treated with Amoxicillin. Antibiotics however do not have any impact on viruses such as colds flu bronchitis or other viral infections because a virus is not alive.

The majority of antibiotic substances are natural products that certain bacteria and fungi (molds) produce and send outside of their cells. About 90% of the antibiotics in use today are isolated from bacteria. There are a few antibiotics however which are completely synthetic as they are made from scratch in the laboratory. These particular antibiotics are designed to inhibit some process previously identified to be completely unique to bacteria and necessary for the bacterium to remain alive.

Antibiotics are generally safe and should always be taken as prescribed by your doctor. Antibiotics may alter the effectiveness of other medications including the birth control pill and cause side effects such as stomach upsets diarrhea or allergic reactions.

Each time we take antibiotics sensitive bacteria are killed but resistant ones may be left to grow and multiply. These resistant bacteria will then be less sensitive to the same antibiotic next time it is needed. The result of this is called antibiotic resistance. When infection-causing bacteria become immune to the effects of certain antibiotics.

Repeated use or improper use of antibiotics are some of the main causes of the increase in resistant bacteria however they also include demand for antibiotics when antibiotics are not called for failure to finish an antibiotic prescription and availability of antibiotics in some countries without a prescription.

Bacteria can acquire resistance by getting a copy of a gene encoding an altered protein or an enzyme. If a bacterium gets a resistance gene stuck into its chromosomal DNA all of its descendants will inherit the gene and the resistance to the antibiotic.

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