Efficacy of Inhalational Ciprofloxacin (Apulmiq) in an NHP Model of Q Fever.

BACKGROUND/

OBJECTIVES

Q fever, caused by Coxiella burnetii, is a zoonotic disease usually treated with doxycycline, but alternative options are needed when doxycycline is unsuitable. This study evaluated inhaled liposomal ciprofloxacin (Apulmiq®) as a post-exposure prophylaxis (PEP) compared with oral doxycycline in a common marmoset model.

METHODS

Marmosets were exposed to aerosolised C. burnetii and treated 24 h later with Apulmiq (0.8 mg/kg inhaled), doxycycline (6 mg/kg oral), or placebo for 7 days. Outcomes included fever, weight loss, bacterial burden, histopathology, liver enzymes, and immune responses.

RESULTS

Both treatments delayed fever onset and reduced disease severity versus placebo. Doxycycline prevented fever during treatment and significantly reduced bacterial loads in the lungs and spleen by Day 28. Apulmiq slightly delayed the onset of fever and reduced early bacteraemia but was less effective at bacterial clearance. Immune analyses showed macrophage activation and elevation of IFN-γ during acute infection, and adaptive immune responses by Day 28.

CONCLUSIONS

Inhaled Apulmiq provided partial prophylactic protection but did not achieve bacterial clearance. Doxycycline reduced bacterial burden but did not completely eliminate disease. Inhaled antibiotics may have potential for use as an alternative approach for PEP treatment, although further optimisation and investigation are needed.