Side effects of antibiotics on genetic variability

In recent years, there has been accumulating evidence that antibiotics, besides their antimicrobial action, potentially have a number of undesired side effects that can, at least in some cases, promote genetic variability of bacteria. In addition to resistant variants, antibiotics have also been shown to select mutator clones, thus stimulating evolution towards further resistance. Furthermore, mutations, recombination and horizontal gene transfer have been reported to be somehow affected when bacteria are exposed to subinhibitory concentrations of certain antibiotics. These findings may have implications for the use of antibiotics, because they may have undesired side effects, such as enhancing antibiotic resistance evolution. Here we present data supporting (or not) this fearsome possibility and discuss whether this potential threat should be taken into considerationThis work was supported by Grants PI070215 and Spanish Network for the Research in Infectious Diseases (REIPI RD06/0008) from Ministerio de Sanidad y Consumo (MSC), Instituto de Salud Carlos III (ISCIII). A.C. was supported by a fellowship (FI05/00569) from MSC-ISCIII.Peer reviewe