Effect of topical ciprofloxacin/dexamethasone or dexamethasone alone on acute Streptococcus pneumoniae rhinosinusitis in mice

To test whether intranasal ciprofloxacin/dexamethasone or dexamethasone alone affects the course of acute bacterial rhinosinusitis in mice.

We performed a randomized, double‐blind, parallel, placebo‐controlled study in mice.

Three groups of 10 C57B1/6 mice were infected with Streptococcus pneumoniae, and then 1 day later randomized to treatment with placebo, ciprofloxacin plus dexamethasone, or dexamethasone. The mice were killed 3 or 10 days after treatment was begun.

The placebo‐treated mice became infected and developed an inflammatory cell infiltration in their sinuses. None of the treatments significantly affected the course of the illness.

The lack of topical, intranasal efficacy of ciprofloxacin and dexamethasone could be attributed to subpotent dosage, rapid nasal clearance, or inability of the drops to reach the site of infection. Treatment with dexamethasone neither improved nor worsened the bacterial infection.