Mechanism of Resistance

Alteration of target protein
Structural change — alteration of DNA gyrase
Overproduction — increased amount of target enzyme

Reduced access to target
Reduction in cell wall permeability to ABX — imipenem resistance
Alteration in PBP — MRSA
Actively pumping out ABX from cell — tetracycline resistance

Enzymatic inactivation of antibiotic
… beta lactam / aminoglycoside resistance