Abstract Efficient treatment of anthrax related meningitis in patients poses a significant therapeutic challenge. Previously we demonstrated in our anthrax meningitis rabbit model that ciprofloxacin treatment in ineffective with most of the treated animals succumbing to the infection. Herein we tested the efficacy of Doxycycline in our rabbit model and found it highly effective. To test whether the low efficacy of Ciprofloxacin is an example of low efficacy of all fluoroquinolones or only this substance, we treated rabbits that were inoculated intra cisterna magna (ICM) with Levofloxacin or Moxifloxacin. We found that in contrast to Ciprofloxacin, Levofloxacin and Moxifloxacin were highly efficient in treating lethal anthrax related meningitis in rabbits. We demonstrated (in naïve rabbits) that this deference probably results from variances in blood brain barrier (BBB) penetration of the different fluoroquinolones. The combined treatment of doxycycline and any one of the tested fluoroquinolones was highly effective in the rabbit CNS infection model. The combined treatment of doxycycline and levofloxacin was effective in inhalation rabbit model, as good as the doxycycline monotherapy. These findings imply that while Ciprofloxacin is highly effective as a post exposure prophylactic drug, using this drug to treat symptomatic patients should be reconsidered.

Doxycycline Levofloxacin or Moxifloxacin are superior to ciprofloxacin in treating anthrax meningitis in rabbits