Since most bacterial cells are starving, they must enter a resting stage. Persister is the term used for metabolically-dormant cells that are not spores, and these cells arise from stress such as that from antibiotics as well as that from starvation. Because of their lack of metabolism, persister cells survive exposure to multiple stresses without undergoing genetic change; i.e., they have no inherited phenotype and behave as wild-type cells once the stress is removed and nutrients are presented. In contrast, mutations allow resistant bacteria to grow in the presence of antibiotics and slow growth allows tolerant cells to withstand higher concentrations of antibiotics; hence, there are three closely-related phenotypes: persistent, resistant, and tolerant. In addition, since dormancy is so prevalent, persister cells must have a means for resuscitating (since so many cells should obtain this resting state). In this review, we focus on what is known about the formation and resuscitation of persister cells.
Keywords: antimicrobial agents; persistence; tolerance.