Opening plugged tympanostomy tubes: effect of biofilm formation

To determine if the presence of a bacterial biofilm impacts the rate of clearing of mucoid plugs from tympanostomy tubes (TTs).

Ex vivo model. Stainless steel Reuter Bobbin TTs (n = 18) were placed in growth medium with Pseudomonas aeruginosa and Streptococcus pneumoniae for 12 days to promote biofilm formation. Tympanostomy tubes (n = 18) placed in growth medium, without bacteria, for 12 days served as controls. Biofilm formation was assessed by scanning electron microscopy. All TTs were filled with middle ear mucus and allowed to dry, thereby forming a plug. TTs were placed in a model ear chamber, covered with ofloxacin otic solution, and the time to clear each plug was recorded.

Biofilm formation was consistently encountered on TTs exposed to bacteria but in no TTs in the control group. There was a significant effect of the biofilm on plug clearance, favoring TTs without a biofilm (P = 0.0333). Although there was no significant difference in the proportion of unplugged TTs (P = 0.264), TTs with a biofilm did not clear plugs as rapidly as TTs without a biofilm (P = 0.0416).

The presence of a biofilm may slow the time to clear mucoid TT plugs, but it does not seem to affect the overall proportion of TTs that are unplugged.