title: Otopathogenic Pseudomonas aeruginosa strains as competent biofilm formers.
abstract: OBJECTIVE
  To determine whether Pseudomonas aeruginosa, a common cholesteatoma pathogen, known to form biofilms in other chronic infections, is capable of contributing to biofilm formation in cholesteatoma.
  
  
  METHODS
  We tested 12 OPPA isolates for several aspects of biofilm formation, including adherence to human keratinocytes, expression of quorum-sensing genes, twitching motility, and production of extracellular matrix as determined by both crystal violet staining and carbazole reaction.
  
  
  RESULTS
  Ten OPPA strains demonstrated increased adherence (1.5- to 12-fold) to human keratinocytes relative to PAO1, a laboratory strain. Expression of las and rhl quorum-sensing products were detected in 11 OPPA strains. By crystal violet staining, we found biofilm formation in all OPPA strains equal to or greater than that found in PAO1 (2- to 18-fold). In addition, OPPA strains demonstrated mucoid characteristics, including down-regulation of twitching motility and increased alginate production.
  
  
  CONCLUSIONS
  Strains of OPPA isolated from cholesteatoma are strongly adherent to keratinocytes and capable of forming biofilm. In addition, OPPA strains have mucoid characteristics in vitro. When these bacteria assume a biofilm phenotype, they are highly resistant to antibiotics and host defenses. These data suggest that OPPA can contribute to biofilm formation in cholesteatoma, leading to the persistence of this infection.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Wang
authors.forename: Jae Y
authors.initials: JY
authors.lastname: Jung
authors.forename: Mary E
authors.initials: ME
authors.lastname: Pashia
authors.forename: Robert
authors.initials: R
authors.lastname: Nason
authors.forename: Steven
authors.initials: S
authors.lastname: Scholnick
authors.forename: Richard A
authors.initials: RA
authors.lastname: Chole
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects / Q000235:genetics; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002448:Cell Adhesion / Q000187:drug effects / Q000235:genetics; D002781:Cholesteatoma / Q000235:genetics / Q000382:microbiology; D003550:Cystic Fibrosis / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D006801:Humans; D015603:Keratinocytes / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D011014:Pneumonia / Q000382:microbiology; D011552:Pseudomonas Infections / Q000235:genetics / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C088386:homoserine lactone; D015107:4-Butyrolactone