2.1 Antibiotic resistance mechanisms

Bacteria have evolved several sophisticated antibiotic resistance mechanisms. Figure 15 gives an overview of the major mechanisms by which bacteria become resistant to the action of antibiotics. Don’t worry if you don’t understand all of these terms, as they will be explained in the following sections.

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Figure 15 An overview of the mechanisms of antibiotic resistance.

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This figure is a schematic diagram giving an overview of the mechanisms of antibiotic resistance. The bacterial cell is represented by a brown oval and the cell wall/membrane is represented in orange surrounding the bacterial cell. Antibiotics (shown as blue spheres) are shown (using red arrows) crossing the cell wall and binding to their target (in green). Enzymes that destroy or modify the antibiotic or target are shown in orange. The following mechanisms are illustrated; modifying the target, protecting the target, amplifying the target, preventing antibiotic entry, increasing efflux, modifying the antibiotic and destroying the antibiotic.

Figure 15 An overview of the mechanisms of antibiotic resistance.

In this section you will look at the three main mechanisms of antibiotic resistance:

• modifying the antibiotic target
• destroying or modifying the antibiotic
• preventing the antibiotic from reaching its target.

Although you will look at each of these mechanisms in turn, it is worth remembering that bacteria may use multiple resistance strategies simultaneously to survive exposure to antibiotics.