Topical antibiotic treatment reduces tympanostomy tube biofilm formation


  • Financial support for this study was provided by the University of Florida. Tympanostomy tubes were provided by Medtronic ENT (Jacksonville, FL) and Ciprodex Otic was provided by Alcon Laboratories (Ft. Worth, TX). Drs. Thomas and Ojano-Dirain have no financial conflicts to disclose. Dr. Antonelli has previously received financial support from Medtronic ENT (grant support and consulting fees) and Alcon Laboratories (grant support and honoraria for speaking engagements and advisory board service).



Single doses of different ototopical antibiotic preparations (OAPs) have been shown to have an unequal reduction of post tympanostomy tube otorrhea (PTTO). Microbial biofilm formation on the tympanostomy tube (TT) has been implicated as one cause of PTTO. The goal of this study was to determine if TT exposure to a single dose of OAP reduces biofilm formation by Pseudomonas aeruginosa.

Study Design:

Prospective and controlled.


Fluoroplastic TTs were briefly exposed to plasma, followed by one of three OAPs (ofloxacin, neomycin/polymyxin B/hydrocortisone, or ciprofloxacin/dexamethasone) or saline (20 TT per group). TTs were placed in growth media with P. aeruginosa and incubated for 4 days, during which total bacterial growth was monitored by media turbidity. At 4 days, planktonic organisms were killed and biofilm development was measured with microbial counts.


Bacterial growth was significantly delayed by OAPs, with the least growth seen with ciprofloxacin/dexamethasone followed by ofloxacin and neomycin/polymyxin B/hydrocortisone (P ≤ .0001). At day 4, bacterial growth was less with ciprofloxacin/dexamethasone than ofloxacin and neomycin/polymyxin B/hydrocortisone (P < .05). After 4 days, biofilm counts were lower on OAP-treated than saline-treated TTs (P = .0015) with both ciprofloxacin/dexamethasone and ofloxacin significantly less than saline (P < .05). Biofilm counts were not significantly different between OAPs (P > .05).


Treatment of TTs with ototopical antibiotic preparations reduces P. aeruginosa growth and biofilm formation in vitro. This may, in part, explain the reduction of PTTO rates observed with single doses of OAPs.