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Updated: Jun 2, 2026
Microtiter Dish Biofilm Formation Assay
Published on: January 30, 2011
Pseudomonas biofilm formation after Haemophilus infection
Carolyn Ojano-Dirain1, Patrick J Antonelli
1Department of Otolaryngology, University of Florida, Gainesville, FL, USA.
Objectives:
Tympanostomy tube (TT) biofilm formation may lead to refractory otorrhea and occlusion. Biofilms are commonly composed of multiple microbial species. One species may promote or inhibit biofilm formation by other species.The aim of this study was to determine if Haemophilus influenzae(HI) promotes the development of Pseudomonas aeruginosa(PA) biofilm on TTs.
Study Design:
Controlled, in vitro.
Setting:
Academic research laboratory.
Subjects And Methods:
Fluoroplastic TTs (20 per group) were exposed to plasma, allowed to dry, and cultured with HI for 7 days. TTs were either gas sterilized or treated for 24 hours with 10 or 3000 μg/mL ciprofloxacin. Half of the TTs from each treatment group underwent bacterial counts or scanning electron microscopy. The remainder, as well as TTs not exposed to HI, were cultured with PA for 4 days and treated with gentamicin to kill planktonic PA. Biofilm formation was quantified with bacterial counts.
Results:
TTs treated with ciprofloxacin 3000 μg/mL had lower HI counts than TTs treated with 10 μg/mL (P = .0001), but viable HI persisted. PA biofilm formation on TTs with prior HI biofilm and treated with ciprofloxacin 10 μg/mL or gas sterilization was not different than TTs without HI. Less PA biofilm formed on TTs with HI treated with 3 mg/mL ciprofloxacin(P = .002).
Conclusions:
HI biofilm does not promote PA biofilm formation on TTs. Use of high-dose ototopical therapy to clear HI may reduce subsequent PA biofilm formation.
Insights
Haemophilus influenzae biofilm does not promote Pseudomonas aeruginosa biofilm on tympanostomy tubes. High-dose ciprofloxacin may reduce subsequent biofilm formation on tympanostomy tubes.
Area of Science:
- Otolaryngology
- Microbiology
- Biomaterials Science
Background:
- Tympanostomy tube (TT) biofilms can cause persistent ear infections and blockage.
- Biofilms often contain multiple bacterial species, where one may influence others.
Purpose of the Study:
- To investigate if Haemophilus influenzae (HI) promotes Pseudomonas aeruginosa (PA) biofilm development on tympanostomy tubes.
Main Methods:
- In vitro study using fluoroplastic TTs exposed to HI.
- TTs were treated with varying concentrations of ciprofloxacin or gas sterilization.
- Subsequent exposure to PA and quantification of biofilm formation.
Main Results:
- High-dose ciprofloxacin (3000 μg/mL) reduced HI counts but did not eliminate it.
- Prior HI biofilm did not enhance PA biofilm formation on TTs treated with lower ciprofloxacin dose or gas sterilization.
- High-dose ciprofloxacin treatment with prior HI exposure resulted in less PA biofilm.
Conclusions:
- Haemophilus influenzae biofilm does not promote Pseudomonas aeruginosa biofilm formation on tympanostomy tubes.
- High-dose ototopical ciprofloxacin may inhibit subsequent PA biofilm development on TTs.
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