# Inhaled Ciprofloxacin as an Alternative Treatment for Infection with Coxiella burnetii

## TL;DR

This study explores inhaled ciprofloxacin as a better treatment for Q fever, showing it reduces lung infection and symptoms more effectively than current options.

## Contribution

The study introduces inhaled liposomal ciprofloxacin as a novel treatment for Q fever pneumonia in a mouse model.

## Key findings

- Inhaled ciprofloxacin reduced clinical signs, weight loss, and lung bacterial burden more effectively than doxycycline.
- Lung inflammation and lesion severity were significantly decreased with inhaled formulations compared to untreated controls.
- Systemic ciprofloxacin was less effective in controlling pulmonary infection than inhaled formulations.

## Abstract

Background/Objectives: Q fever, caused by Coxiella burnetii, is typically treated with doxycycline, but its efficacy is limited in chronic cases and may be poorly tolerated. Systemic ciprofloxacin shows limited activity for acute Q fever. However, inhaled liposomal formulations may provide therapeutic benefit. Methods: Two inhaled ciprofloxacin formulations (Lipoquin® and Apulmiq®) were evaluated in an A/J mouse model of Q fever and compared with intraperitoneal ciprofloxacin and oral doxycycline. Initially, pharmacokinetic studies were performed to determine an appropriate dosing regimen for the inhaled ciprofloxacin formulations. A separate cohort of mice were then infected with C. burnetii and treated once daily via nebulisation with Lipoquin or Apulmiq, initiated at 24, 48, or 72 h post-challenge. Clinical signs, weight change, splenomegaly, bacterial burden, and lung histopathology were evaluated. Results: Pharmacokinetic analysis confirmed sustained lung concentrations of inhaled ciprofloxacin, supporting once-daily dosing. Inhaled Lipoquin and Apulmiq significantly reduced clinical signs, weight loss, splenomegaly, and pulmonary bacterial burden compared to untreated controls and doxycycline-treated mice. Histopathology revealed decreased lung inflammation and lesion severity following inhalational dosing. Systemic ciprofloxacin slightly reduced splenic bacterial burden but was less effective in controlling pulmonary infection. Conclusions: Inhaled liposomal ciprofloxacin demonstrated superior protection and reduced respiratory manifestations of Q fever compared to doxycycline and systemic ciprofloxacin. These findings suggest inhaled formulations may represent a viable alternative for the treatment of Q fever pneumonia. Further studies are needed to evaluate clinical applicability and long-term outcomes.