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Antibiotic Resistance

Antibiotic resistance is the ability of a microorganism to withstand the effects of an antibiotic. It is a specific type of drug resistance. There are two major mechanisms by which bacteria can become resistant to antibiotics: (i) mutations in the bacterial genome, or (ii) acquisition of genes that code for resistance by horizontal gene transfer, often mediated by plasmids. If a bacterium carries several resistance genes, it is called multiresistant or, informally, a superbug.

There are several different ways that bacteria are able to reduce their susceptibility to antibiotic drugs. The first mechanism is inactivating the drug and modifying it so that it is no longer harmful to the bacteria. Similarly, the antibiotic becomes ineffective when a mutation arises in the target molecule so that it is no longer affected by the drug. Another way to avoid the ill effects of an antibiotic is by circumventing the metabolic pathway targeted by the drug. This can be done by acquiring the product of the metabolic pathway from the environment. Finally the bacteria can reduce the effect of the drug by reducing the concentration of the drug in the cell. They do this either by making the cell less permeable to the drug or by actively pumping it out of the cell. - see also, wikipedia

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