Acquired tetracycline resistance genes

Tetracycline continues to be used as treatment for a variety of infections due to Gram-positive, Gram-negative, intracellular bacteria, some protozoan infections, and noninfectious conditions [12, 65]. Tetracycline is also an important antibiotic for prophylaxis or treatment either alone or in combination with other antibiotics and for agents of biological terrorism [Bacillus anthracis, Francisella tularensis, and/or Yersinia pestis] [64]. Hughes and Data [29] examined Enterobacteriaceae collected between 1917 and 1954 for tetracycline resistance [Tc] and found that 2% of the 433 isolates were Tc, with the first Tc bacteria found in the 1950s isolates. From this work, it was suggested that the discovery of Tc bacteria was a relatively recent event and an unintended consequence of tetracycline use in clinical, veterinary, and agricultural experiments since the 1950s.