<prompt> Although tetracycline is a broad-spectrum antibiotic but resistance to the drug developed by the following mechanism:By inactivating enzymes.An efflux pump mechanism.Alteration of the binding site.Absence of a metabolic pathway.  <response>: Tetracyclines are broad-spectrum bacteriostatic drugs. Development of resistance to tetracyclines are mainly due to the development of efflux pumps. 