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Updated: Jul 19, 2026
Intratracheal Inoculation of Fischer 344 Rats with Francisella tularensis
Published on: September 30, 2017
Finafloxacin Is an Effective Treatment for Inhalational Tularemia and Plague in Mouse Models of Infection
Kay B Barnes1, Mark I Richards1, Thomas R Laws1
1Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom.
Abstract:
Infection with aerosolized Francisella tularensis or Yersinia pestis can lead to lethal disease in humans if treatment is not initiated promptly. Finafloxacin is a novel fluoroquinolone which has demonstrated broad-spectrum activity against a range of bacterial species in vitro, in vivo, and in humans, activity which is superior in acidic, infection-relevant conditions. Human-equivalent doses of finafloxacin or ciprofloxacin were delivered at 24 h (representing prophylaxis) or at 72 or 38 h (representing treatment) postchallenge with F. tularensis or Y. pestis, respectively, in BALB/c mouse models. In addition, a short course of therapy (3 days) was compared to a longer course (7 days). Both therapies provided a high level of protection against both infections when administered at 24 h postchallenge, irrespective of the length of the dosing regimen; however, differences were observed when therapy was delayed. A benefit was demonstrated with finafloxacin compared to ciprofloxacin in both models when therapy was delivered later in the infection. These studies suggest that finafloxacin is an effective alternative therapeutic for the prophylaxis and treatment of inhalational infections with F. tularensis or Y. pestis.
Insights
Finafloxacin offers effective protection against aerosolized Francisella tularensis and Yersinia pestis infections in mice, especially when treatment is delayed. This novel fluoroquinolone shows promise as an alternative therapeutic for these serious bacterial threats.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Inhalational infections caused by *Francisella tularensis* and *Yersinia pestis* pose significant lethal risks to humans.
- Prompt treatment initiation is critical for managing these severe bacterial infections.
- Finafloxacin, a novel fluoroquinolone, exhibits broad-spectrum antimicrobial activity, particularly effective under acidic, infection-relevant conditions.
Purpose of the Study:
- To evaluate the efficacy of finafloxacin compared to ciprofloxacin for prophylaxis and treatment of *F. tularensis* and *Y. pestis* inhalational infections.
- To assess the impact of delayed treatment initiation on the effectiveness of these antibiotics.
- To compare short-term versus long-term dosing regimens for finafloxacin and ciprofloxacin.
Main Methods:
- BALB/c mouse models were challenged with aerosolized *F. tularensis* or *Y. pestis*.
- Human-equivalent doses of finafloxacin or ciprofloxacin were administered at 24 hours (prophylaxis) or 72/38 hours (treatment) post-challenge.
- Therapy durations of 3 days and 7 days were compared.
Main Results:
- Both finafloxacin and ciprofloxacin provided high protection when administered 24 hours post-challenge, regardless of treatment duration.
- Delayed administration of therapy revealed significant differences between the two antibiotics.
- Finafloxacin demonstrated a clear benefit over ciprofloxacin when treatment was initiated later in the course of infection.
Conclusions:
- Finafloxacin is a potential alternative therapeutic agent for both prophylaxis and treatment of inhalational *F. tularensis* and *Y. pestis* infections.
- The efficacy of finafloxacin is particularly notable in scenarios involving delayed treatment initiation.
- These findings support finafloxacin's role in managing severe bacterial infections relevant to biodefense.
