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Mechanism of Antibiotic Resistance
Source: Levy, SB. The challenge of antibiotic resistance. Sci Am. March 1998:46-53. Organisms that are resistant to antibiotics possess genes carried either on the bacterial chromosome or on small circular DNA plasmids, which, direct the synthesis of traits, which, protect bacteria from antibodies. Certain resistance genes are responsible for enzymes that degrade or chemically modify, and so inactivate, antibiotics. Other resistance genes may cause bacteria to modify or replace molecules that are normally bound by an antibiotic, thus effectively removing the drug's target. Resistant bacteria may also possess genes that mediate the elimination of the entry ports into the cell, or that cause efficient efflux pumps to export the antibiotic from the cell before it has met its target.
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