Infectious diseases caused by bacteria, viruses, fungi and parasites are one of the main causes of mortality in the world. Countless lives have been saved by the discovery, and the use of antibiotics. Nevertheless, bacteria have a great capacity of response and are developing ever more ingenious mechanisms of resistance. In fact, resistance mechanisms have been observed for almost all available antibiotics.
Resistant bacteria are easily selected and disseminated in some particular settings and some bacteria are now resistant to most antibiotics, sometimes leaving only very few alternative treatments.