Effect of Delaying Treatment on Efficacy of Ciprofloxacin and Levofloxacin in the African Green Monkey Model of Pneumonic Plague

Ciprofloxacin and levofloxacin, 2 fluoroquinolone antimicrobials, are ≥90% effective for the treatment of inhalational plague when administered within 2-6 hours of fever onset in African green monkeys (AGM). Based on data in the AGM model, these antimicrobials were approved under the Food and Drug Administration's Animal Efficacy Rule. However, that data did not address the issue of how long treatment with these antimicrobials would remain effective after fever onset.