ABSTRACT
Until the 1990s, it was commonly thought that infectious diseases would not be a problem anymore because antibiotics were extremely successful for their treatment. In fact, in 1969, the U.S. Surgeon General, William H. Stewart, stated in the U.S. Congress, "The time has come to close the book on infectious diseases" (Wilson 2002). However, according to the World Health Organization, 40% of the 50 million deaths produced in the year 2000 were the consequence of infectious diseases (World Health Organization 2000). One of the causes of this situation is the widespread dissemination of antibiotic resistant pathogenic bacteria among human populations and in the environment. In fact, antibiotic resistance is one of the most relevant problems in current medicine (Neu 1992).
