article : Physiological and Biochemical Mechanisms of Drug Resistance

Bacteria may Demonstrate any of Five General Mechanisms of Antibiotic Resistance:

1. Lack of entry; Decreased cell permeability
2. Greater exit; Active efflux
3. Enzymatic inactivation of the antibiotic
4. Altered target; Modification of drug receptor site
5. Synthesis of resistant metabolic pathway

These Mechanisms can be Grouped into Three Broad Categories:

Permeability Mechanisms

Lack of entry; Decreased cell permeability

Greater exit; Active efflux

Enzymatic Inactivation of the Antibiotic Altered Target or Pathway

Altered target; Modification of drug receptor site

Synthesis of resistant metabolic pathway