Objective: Ciprofloxacin resistance has been reported in 4.5% of patients with otorrhea and is increasing in prevalence. Due to ototoxicity, only fluoroquinolones are Food and Drug Administration approved for topical therapy in the middle ear. Furthermore, there is an assumption that antibiotic resistance is less relevant to topical therapy due to in vivo concentrations much higher than the minimum inhibitory concentration used to determine resistance. This study investigates ciprofloxacin-resistant infections and seeks to develop a better understanding of treatment options and outcomes.
Study design: Retrospective review of 141 ciprofloxacin-resistant otologic infections.
Setting: Tertiary-care hospital.
Patients: Patients with culture-proven ciprofloxacin-resistant infections from 2008 to 2017.
Intervention(s): Antibiotic treatment with ciprofloxacin topical drops, ciprofloxacin plus oral antibiotics, and nonciprofloxacin therapy.
Main outcome measure(s): Bacteriology for ciprofloxacin-resistant infections and treatment effectiveness of various therapies.
Results: Methicillin-resistant Staphylococcus aureus (33%), Corynebacterium striatum (19%), and non-Methicillin-resistant Staphylococcus aureus (11%) are the most frequent causes of ciprofloxacin-resistant infections. Topical ciprofloxacin monotherapy was successful in 2.7% of infections compared with a 64.7% success rate with the addition of an oral antibiotic (p < 0.001). Nonciprofloxacin drops are more effective with a 70% cure rate compared with the 2.7% of the ciprofloxacin drops p < 0.001. There was no difference in treatment efficacy when comparing nonciprofloxacin topical therapy (70% cure) to nonciprofloxacin topical therapy plus oral antibiotic (83% cure, p = 0.17).
Conclusions: Using ciprofloxacin drops to treat ciprofloxacin-resistant bacteria is ineffective and patients do significantly better with alternative therapy. This finding supports the conclusion that high concentrations achieved in topical applications are not sufficient to overcome antibiotic resistance.