Optimized Method for Measuring Persistence in Escherichia coli with Improved Reproducibility.

Monitoring persister cells can be extremely difficult due to their transient and stochastic nature, their low abundance, and their resemblance to Viable But Non-Culturable Cells (VBNCs). To date, the predominant method consists of determining the survival rate of a bacterial population after antibiotic treatment as a function of time or antibiotic concentration. Unfortunately, this method is limited, as it shows high levels of dispersion of the data around the mean, making interpretation difficult. Furthermore, additional reproducibility problems arise from the lack of a standard method, different research groups using different protocols. Here, we describe a standard and optimized method for monitoring E. coli persister cells at the population level allowing for maximal reproducibility.