Effect of ototopical medications on tympanostomy tube biofilms.
OBJECTIVE
Examine how ototopical medications affect biofilms on fluoroplastic tympanostomy tubes.


METHODS
In vitro comparison of different ototopical medications against a clinical isolate of Pseudomonas aeruginosa biofilm on tympanostomy tubes treated for 5, 10, 14, and 21 days.


METHODS
Under sterile conditions 21 tympanostomy tubes were cut in half. These were attached to pegs of two Calgary Biofilm Devices via rubber cement. Device 1 evaluated microbial growth as colony forming units (CFUs). Device 2 evaluated presence of biofilms. Tubes were prepped for biofilm growth, incubated, and stressed for 72 hours. Afterward, one tube per device was removed and forcefully washed. One was sonificated for 5 minutes, serially diluted, and plated for CFUs. Formalin preserved the other for biofilm evaluation by scanning electron microscopy. Next, tubes were exposed to five drops of Ciprofloxacin, Ciprofloxacin/Dexamethasone, Dexamethasone, Ofloxacin, or saline for 1 hour. Afterward, the ototopicals were removed and sterile broth was placed in the wells as a nutrient. This was repeated every 12 hours for 5, 10, 14, and 21 days of treatment. Prior to the last dose of treatment intervals, a streak plate was performed to evaluate for microbial growth in the wells. The tubes were evaluated for CFUs and biofilms at each interval as previously described.


RESULTS
Microbial activity in CFUs decreased by day 5 and continued through day 21 for the antibiotic containing drops. Despite treatment, the biofilm was never eradicated and continued to progress.


CONCLUSIONS
Infectivity of the biofilm is neutralized by antibiotic ototopicals; however, the biofilm will progress despite treatment.
Oxley
K Scott
KS
Department of Otolaryngology-Head and Neck Surgery, West Virginia University, Morgantown, West Virginia, USA.
Thomas
John G
JG
Ramadan
Hassan H
HH
D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D018441:Biofilms; D002939:Ciprofloxacin / Q000494:pharmacology* / Q000627:therapeutic use*; D003907:Dexamethasone / Q000494:pharmacology* / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D004338:Drug Combinations; D004359:Drug Therapy, Combination; D004866:Equipment Contamination / Q000706:statistics & numerical data*; D006801:Humans; D008876:Middle Ear Ventilation / Q000706:statistics & numerical data*; D015242:Ofloxacin / Q000494:pharmacology* / Q000627:therapeutic use*; D016459:Prosthesis-Related Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D013997:Time Factors
D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D004338:Drug Combinations; D002939:Ciprofloxacin; D003907:Dexamethasone; D015242:Ofloxacin