title: Pseudomonas biofilm formation after Haemophilus infection.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Controlled, in vitro.
  
  
  METHODS
  Academic research laboratory.
  
  
  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.
authors.affiliation: Department of Otolaryngology, University of Florida, Gainesville, FL, USA.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Ojano-Dirain
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Antonelli
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D058491:Bacterial Load; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002408:Catheters, Indwelling / Q000382:microbiology*; D015169:Colony Count, Microbial; D004866:Equipment Contamination / Q000517:prevention & control*; D005839:Gentamicins / Q000494:pharmacology; D006193:Haemophilus influenzae / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D008876:Middle Ear Ventilation / Q000295:instrumentation; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins