Validation of SYBR Green I/PI assay in comparison to microscopic counting for determining antibiotic susceptibility of B. burgdorferi.1.

1A 5-day B. burgdorferi culture was treated with 1 mM each of doxycycline, amoxicillin or metronidazole for 5 days, followed by staining with LIVE/DEAD assay and SYBR Green I/PI assay, or microscope counting (as a gold standard) to assess their capability for antibiotic susceptibility testing. The green/red ratios were obtained for LIVE/DEAD and SYBR Green/PI assays respectively in fluorescence measurement (see Methods). Each value is the mean of three replicates.2The percentage of live (green) spirochetes.Validation of SYBR Green I/PI assay in comparison to microscopic counting for determining antibiotic susceptibility of B. burgdorferi.1.