How to tackle the problem of ciprofloxacin-resistant ear infections?
Reviewed by Aileen Lambert

The growing issue of ciprofloxacin-resistant ear organisms is certainly a pertinent one. The situation here in the UK, where ototoxic topical drops are frequently given initially in the presence of pus and a perforation, differs markedly from elsewhere where fluoroquinolones are first-line treatment in that scenario. This paper from the House Institute in LA, looking at 141 ciprofloxacin-resistant infections over an eight-year period, aims to tackle the view that resistant infections can still be treated with topical ciprofloxacin. This had been driven by the belief that high concentrations obtained with topical antibiotic preparations would overcome all minimum inhibitory concentration (MIC) levels encountered. In this retrospective study ciprofloxacin-resistance was identified in 12.6% of all cultures taken in that period, predominantly due to MRSA (31%) and corynebacterium infections (27%). In their results, treatment of proven ciprofloxacin-resistant infection with non-ciprofloxacin ear drops (e.g. tobramycin, neomycin and polymixin B sulfates with hydrocortisone, and gentamicin drops) were more effective, with a 70% cure rate, compared with the 2.7% cure rate of the ciprofloxacin drops (p<0.001). This was also higher than when oral antibiotics were given (67% cure rate). This group also interestingly report that the most common type of infection associated with ciprofloxacin resistance is post-tympanostomy otorrhea, suggesting a possible role of biofilms in the development of resistance. The concern of ototoxicity from alternative topical drops was explored, and 2.7% (two patients) had symptoms post-treatment which they say may be attributable to this effect. The results of this study do not support the practice of treating resistant ciprofloxacin infections simply with higher drug concentrations (i.e. topical drops), and encourage the use of swabs to direct therapy, which may include potentially ototoxic preparations. The role of oral antibiotics in these infections was not able to be answered by this retrospective study as too few patients were treated with oral monotherapy. The safest and most effective treatment remains to be decided by future prospective research. 

Treatment of ciprofloxacin-resistant ear infections.
Noonan KY, Kim SY, Wong LY, et al.
OTOLOGY AND NEUROTOLOGY
2018;39(9):e837-42.