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| Mechanisms of Resistance |
Various adaptations provide bacteria with antibiotic resistance. Mutations in a target protein that affect binding of an antibiotic to that protein may confer resistance. If an antibiotic inhibits a metabolic pathway and an alternate one becomes available, resistance can occur. Some antibiotic-resistant bacteria make enzymes that destroy drugs; others alter pores in the cell membrane so an antibiotic can no longer enter. Some resistant strains have developed mechanisms for actively pumping antibiotics out of the bacterial cell. The genes for antibiotic resistance are sometimes found on plasmids. The transfer of these plasmids among bacteria facilitates the spread of antibiotic resistance within and between bacterial populations.