2.2.1 Intrinsic resistance

Intrinsic resistance is the innate ability of a bacterium to resist the action of an antibiotic as a consequence of the bacteria’s structural or functional characteristics. In contrast to acquired resistance, which you will look at next, intrinsic resistance is ‘normal’ for bacteria of a given type.

Intrinsic resistance may occur because bacteria lack the target for a particular antibiotic or because the drug can’t get to its target. It reduces the pool of antibiotics available to treat infections.

It is worth noting that resistance elements that are intrinsic to one bacterial type can occasionally be transferred to another one, and you will learn about this below.