Drug Resistance: An Incessant Fight against Evolutionary Strategies of Survival

The inherent capacity of all organisms to evolve under selective pressure has created multidrug-resistant microbes and cells that are now threatening decades of progress in human health introduced by the advent of antibiotics. This resistance is developed by all pathogens, from bacteria to cancer cells, through fungi, parasites, or the seemingly simpler entities, i.e., viruses. In this review, we give an overview on this phenomenon, describing the mechanisms by which resistant organisms manage to evade the action of drugs. We also review existing therapies, including some of the most recent. This bibliographic review shows how, despite the encouraging progress that has been achieved in many areas, a permanent effort from scientists is necessary and will always be needed in order to compensate for the continuous microbial response intrinsically linked to the evolutionary process.