Single cell observations show persister cells wake based on ribosome content

Since persister cells survive antibiotic treatments through dormancy and resuscitate to reconstitute infections, it is imperative to determine the rate at which these cells revive. Using two sets of Escherichia coli persister cells, those arising after antibiotic treatment at low levels and those generated at high levels by ceasing transcription via rifampicin pretreatment (shown to be bona fide persisters through eight sets of experiments), we used microscopy of single cells to determine that the resuscitation of dormant persisters is heterogeneous and includes cells that grow immediately. In all, five phenotypes were found during the observation of persister cells when fresh nutrients were added: (i) immediate division, (ii) immediate elongation followed by division, (iii) immediate elongation but no division, (iv) delayed elongation/division and (v) no growth. In addition, once cell division begins, the growth rate is that of exponential cells. Critically, the greater the ribosome content, the faster the persister cells resuscitate.