Topographic Distribution of Pseudomonal Biofilm on Tympanostomy Tubes – An in vitro Model

Background: Tympanostomy tube (TT) otorrhea is a major complication following tube insertion for recurrent acute otitis media or for long-standing otitis media with effusion associated with hearing loss. It is often associated with a biofilm growth. We sought to determine the in vitro topographic distribution of Pseudomonas aeruginosa biofilm formation on 2 common commercial types of TTs.

Methods: P. aeruginosa PAO1 strain was incubated in a biofilm-forming media with sterile silicon Activent® Paparella-type TTs and Activent® Armstrong silicon to allow formation of biofilm growth. Appropriate fixation and staining were performed on the immobilized bacteria on the TT upon few hours of incubation. The presence and topographic distribution of biofilms on the TTs were evaluated by both a scanning electron microscope and a confocal laser scanning microscope.

Results: In the Paparella-type TTs, most of the bacterial biofilm was located in the perpendicular junction between the main body of the tube and the flanges, whereas in the Armstrong T-tube, biofilms tended to concentrate on the external rims of the tube.

Conclusion: P. aeruginosa biofilm formation tends to appear in specific areas on the TT. These prone zones can be the future target areas for changes in TT geometry, or can be specifically coated with anti-biofilm materials in order to decrease biofilm adherence.