Clementi, E. A., Marks, L. R., Roche-Håkansson, H., Håkansson, A. P. Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes. J. Vis. Exp. (84), e51008, doi:10.3791/51008 (2014).