Comparison of NaCl-P buffer and Ringer solution for viability analysis of B. cepacia and S. aureus by flow cytometry. Viability was determined by membrane integrity analysis using SYBR Green I (dilution of 5 x 103) and PI (5 μg/mL). Relative frequencies of (A) viable and dead cells of B. cepacia and (B) of viable, damaged and dead cells of S. aureus in pure culture from both exponential and stationary growth phase. Relative frequencies were determined based on all SYBR Green I and PI fluorescence positive events. Error bars represent standard deviation of three biological replicates.