TETRACYCLINES - ANTIBIOTIC ACTION, UPTAKE, AND RESISTANCE MECHANISMS

Tetracyclines probably penetrate bacterial cells by passive diffusion and inhibit bacterial growth by interfering with protein synthesis or by destroying the membrane. A growing number of various bacterial spec ies acquire resistance to the bacteriostatic activity of tetracycline. The two widespread mechanisms of bacterial resistance do not destroy tetracycline: one is mediated by efflux pumps, the other involves an E F-G-like protein that confers ribosome protection. Oxidative destructi on of tetracycline has been found in a few species. Several efflux tra nsporters, including multidrug-resistance pumps and tetracycline-speci fic exporters, confer bacterial resistance against tetracycline. Singl e amino acids of these carrier proteins important for tetracycline tra nsport and substrate specificity have been identified, allowing the me chanism of tetracycline transport to begin to emerge.