As common microbiological methods for the assessment of bacteriostatic or bactericidal
activities are very time-consuming, in this work we describe that the use of a novel far-red
fluorescent stain, Vybrant DyeCycle Ruby (DCR) for the flow cytometric analysis of
fluoroquinolone (ciprofloxacin) bacteriostatic and bactericidal activities in Escherichia coli
proved to be specific for bacterial DNA and, after ciprofloxacin exposure, DNA distribution
analysis was achieved using a 7.5 μ M DCR concentration to stain 5× 10 5 ethanol-fixed …

Antibiotics alone or in combination may either inhibit or kill bacteria. Laboratory methods are
available to determine the activity of various antimicrobial agents and can aid the physician
in selecting appropriate antimicrobial therapy for specific infectious disease disorders. A few
infectious processes appear to require bactericidal antimicrobial therapy for cure. Additional
multicenter trials of the ability of a standardized SBT to predict therapeutic outcome in
specific bacterial diseases are required.